Building Blocks for a Precautionary Approach to the Use

Transcription

NanoMatters
BuildingBlocksforaPrecautionaryApproach
PieterJ.C.vanBoekhuizen
Cover design: Nano Matters Pauline van Broekhuizen‐Stutje, Amsterdam (2012) Oil paint on medium‐density fibreboard Photography oil painting: Anton Staartjes NanoMatters
BuildingBlocksforaPrecautionaryApproach
ACADEMISCHPROEFSCHRIFT
terverkrijgingvandegraadvandoctor
aandeUniversiteitvanAmsterdam
opgezagvandeRectorMagnificus
prof.dr.D.C.vandenBoom
tenoverstaanvaneendoorhetcollegevoorpromotiesingesteldecommissie,
inhetopenbaarteverdedigenindeAuladerUniversiteit
opvrijdag21December2012,te15:00uur
door
JacquesCornelisvanBroekhuizen
geborenteAmsterdam
Promotor:
Prof.Dr.L.Reijnders
Overigeleden: Prof.Dr.W.E.Bijker
Prof.Dr.F.J.H.vanDijk
Prof.Dr.W.R.F.Notten
Prof.Dr.W.P.deVoogt
FaculteitderNatuurwetenschappen,WiskundeenInformatica
The work in this thesis was performed at IVAM UvA BV – Research and Consultancy on
Sustainability,PlantageMuidergracht24,1018TVAmsterdam.
ThestudywasfacilitatedbyageneralgrantfromtheUvAHoldingBV.Partsofthestudy
elaborate on other projects such as the capacity building project NanoCap that was
granted by the European FP6, Science and Society Program, grant no. SASͲCTͲ2006–
036754ͲNanoCap, the study within the context of the European Social Dialogue in the
Construction Industry as granted by the European Commission, Directorate General
Employment by the grant agreement no. VS/2008/0500–SI2.512656, a study granted by
Stichting Arbouw to perform exposure measurements in the construction industry, the
pilotprojects‘NanoReferenceValues’and‘Guidanceforsafeworkingwithnanomaterials’,
ascommissionedbytheDutchsocialpartnersFNV,CNVandVNO/NCWwithagrantfrom
the Dutch Ministry of Social Affairs and by many discussions within the frame of the
WorkingConditionsCommitteeoftheDutchSocialEconomicCouncil.
Contents 1. Introduction 1.1. Introduction and questions raised 1.2. A definition for nanomaterials 1.3. Adverse effects of nanomaterials 1.4. The precautionary principle 1.5. Background concentrations and process‐generated nanoparticles 1.6. Exposure limits for nanomaterials 7 9 13 16 22 26 30 2. Building Blocks for a Precautionary Approach to the Use of Nanomaterials: Positions Taken by Trade Unions and Environmental NGOs in the European Nanotechnologies Debate. Pieter van Broekhuizen, Lucas Reijnders 45 3. 3.1 3.2 3.3 59 Use of nanomaterials in the European construction industry and some occupational health aspects thereof. Pieter van Broekhuizen, Fleur van Broekhuizen, Ralf Cornelissen, Lucas Reijnders Use of nanomaterials in the furniture industry The paint value chain and nanomaterials 4. Workplace exposure to nanoparticles and the application of provisional nanoreference values in times of uncertain risks. Pieter van Broekhuizen, Fleur van Broekhuizen, Ralf Cornelissen, Lucas Reijnders 5. Exposure Limit Values for Nanomaterials – Capacity and Willingness of Users to Apply a Precautionary Approach. Pieter van Broekhuizen, Baerbel Dorbeck‐Jung 77 78 81 109 6. Comparison of control banding tools to support safe working with nanomaterials 129 and the role of process‐generated nanoparticles Pieter van Broekhuizen, Hildo Krop, Lucas Reijnders 7. Exposure Limits for Nanoparticles: Report of an International Workshop on Nano Reference Values. Pieter van Broekhuizen, Wim van Veelen, Willem‐Henk Streekstra, Paul Schulte, Lucas Reijnders 153 8. Conclusions Summary Samenvatting Epiloog 165 175 183 193 Chapter1
Introduction
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NanoMatters - Building Blocks for a Precautionary Approach
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8
Introduction
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1.1
Introductionandquestionsraised
S
ince the late nineties of last century the emergence of nanotechnologies1has been
thesubjectofpublicdebate(‘nanodebate’).Nanotechnologiesapplymaterialsatthe
nanoscale, though it may be noted that the range of the nanoscale, which was
formallyrecommendedforlegislativepurposesbytheEuropeanCommissionasmaterials
with a diameter of 1Ͳ100nm, is not precisely defined in terms of risk as will be further
discussedinsection1.2.Thestakeholdergroupsthatcommittedthemselvestotakepartin
the nanodebate are quite divergent being NGOs (e.g. EEB ndͲb, FoE 2007), consumer
organizations (e.g. BEUC), insurance companies (Münchener Rück 2002; Swiss Re 2004;
Allianz nd), religious organizations (Toumey 2012), educational organizations and musea
(Nanototouchnd),tradeunions,andmanyothers.
Contributionstothepublicdebatehaverangedfromhighexpectationsandambitiousroad
maps (e.g. Roco & Bainbridge 2001; Royal Society 2004, KNAW 2004, Roco 2007), to dire
warnings(ETC2003,FoE2007).Themattersraisedhaveincludeditspromisestosolveso
farnotͲeasilysolvableproblemsasfindingnewenergyresourcesandreductionofenergy
use(e.g.Cientifica2007,Lewis2007),cleanwatersupply(e.g.Hillieetal2006,Grimshaw
2009), cleaner food production (e.g. Joseph et al 2006), medicines with targeted drug
delivery(e.g.Park2007),newcancertreatments(e.g.Maynard2010),smartselfͲrepairing
coatings (e.g. Shchukin et al 2007), substitution of toxic substances in products (e.g.
Ellenbecker et al 2011) and many others. Other topics in the nanodebate relate to the
social and ethical issues of introducing nanotechnologies in society (e.g. Sandler 2009,
Gammel 2009) and matters of hazard (potential to harm) and risk (chance that harm will
occur). The importance of the latter matters is linked to findings that a specified mass of
nanomaterialsmaybemorehazardousthanthesamemassoflargersizedmaterials.Thisis
discussed in more detail in section 1.3. The differences in properties between nanosized
andlargersizedmaterialsmayrequireincludingfactorslikesize,form,zetaͲpotentialand
other parameters in hazard assessment (SCENHIR 2009, Shvedova et al 2010). The
properties of nanomaterials may require using new metrics for exposure assessment
departing the conventional massͲbased approach (Oberdörster et al 2005), which is an
important issue for risk assessment and standard setting (see also section 1.6). With the
growingattentiontotheoccupationalhealthrisksofmanufacturednanomaterials(MNMs)
interest is also emerging in nanoparticles that are generated in processes (processͲ
generatednanoparticles–PGNP),whichmaybesimilarlyharmful.Thisisbrieflydiscussed
insection1.5andinlaterchapters.
Special attention in the nanodebate regards the matter of risk governance. One
relevantmatterinthisrespectisthequestionwhetherexistinglegislationcoversthesafe
useofnanomaterials.Initialstudiestoidentifypossiblegapsinexistinglegislationregarding
1
Thewordnanotechnologiesisusedinthepluralformastoexpressitsnatureasenabling
technology.Nanomaterialsandtechnologiesthatstudyandoperateatthenanoscaleareusedin
othertechnologies,likee.g.biotechnology,genomics,coatingtechnology.Assuch
nanotechnologydoesnotexistasindependentdiscipline,butisgenerallycharacterizedasa
convergingtechnology.
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control of potential hazards of nanomaterials resulted in early European and national
governmental statements that existing legislation, in principle, covers the new risks of
nanomaterialsaswell,andonlyslightadaptationsshouldhavetobemadetoaddressthe
nanoscale(EC2008;NL2008).Morerecentstudiesshowthatsometimesmorefundamental
changes in legislation should be considered (VogelezangͲStoute et al 2010); other studies
are still ongoing (DG Empl 2012). The legislation regarding the cosmetics directive has alͲ
ready been “nanonized” under the pressure of consumer organizations and after agreeͲ
ment in the European Parliament (EC 2009). Initiatives to include nanomaterials in the
REACH regulation are ongoing; adaptations have been made in accompanying guidance
documentsaddressingananoͲspecificapproachforidentification,informationrequirement
andriskassessmentofnanomaterials,(ECHA2012).
Giventhepresenttrendtoderegulation,theambitionofgovernmentstodevelop
new legislation is limited and preference is given to selfͲregulating of social partners and
softinstruments.Thelatteremphasizetheresponsibilityofindustrytotakecareforasafe
and acceptable nanotechnological development and advocate a deliberative approach to
give a critical voice to Civil Society Organizations (CSOs) (Renn et al 2006, Widmer et al
2010).InanefforttoframearesponsibledevelopmentofnanotechnologiestheEuropean
Commission launched a voluntary Code of Conduct (CoC) for nanotechnological R&D and
emphasized the need to invoke the precautionary principle when indications of hazard,
uncertainties and ambiguities are at stake (EC CoC 2008, NanoCode 2012). Industry
respondedtothiswiththeirownCoCsorsimilarapproaches,whichiselaboratedfurtherin
section1.4.
More in general, in the debate of risk governance the operationalization of the
precautionaryprinciple (PP)hasbecomeimportant.Allrelevantactorshavinginterestsin
nanomaterials on the European market, being industry, governments and CSOs, tend to
agree on invoking the PP when ambiguity and uncertainty is at stake. It is however
questionable whether they mean the same when they operationalize the PP. Indicative
thereofistheemergenceoftheconcept“precautionaryapproach”,astowhichtheuseof
theword‘approach’maybesuggestalooseinterpretationofthePP(Rip2006).
Other matters that are important in the nanodebate are the balancing of the
uncertainties regarding (health) risks and (economic) benefits, and the problem of trust.
Manyofthestakeholdershaveonlyalimitedtrustinthedownstreaminformationsupply
(Brunetal2012).Problematicin this respectisthelackoftransparencyinthe marketof
nanomaterialsandtheconfidentialityofproductcompositions.Downstreamusersarekept
ignorant to a large extent about the composition of nanoͲenabled products and are
generallynotinformedaboutapossiblereleaseofnanomaterialsduringtheintendeduse
oftheirproducts(seechapter5).Thismatterwillbetakenupinchapter3.
This thesis will partly deal with the emerging position of European trade unions and
environmentalorganizationsinthenanodebateabouthazardandrisk.Alargerpartofthis
thesis will more specifically deal with hazard and risk linked to nanomaterials at the
workplace. The latter part of the thesis is to be viewed against the background of major
developments in workplace risk governance. These include REACH and ‘deregulation’ and
thewaytotranslatetheprecautionaryprincipleintoaprecautionaryapproachthatallows
developingmanufacturednanomaterials(MNMs)andapplyingthesesafelyinproducts.
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Introduction
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Thequestionsraisedinthisthesisregardthefollowingtopics.
1. TheroleofCSOsinthenanodialogue
This thesis focuses on developing precautionary risk management strategies in situations
whereuncertaintiesprevailandeconomicinterestsforceindustriestogofullspeedahead
withnewmaterialsthatcanbemanufacturedatthenanosizeandstudieshowCSOsbuilt
theircapacitytopositionthemselvesinthenanodebate.Section1.5shortlyintroducesthe
dilemmas around making the precautionary principle operational. Chapter 2 goes into
detailaboutthecapacitybuildingofCSOsandtheirinitiativetodevelop“buildingblocksfor
aprecautionaryapproach”.
Questionsraisedare:
a) What is the role of CSOs in the dialogue on the responsible development of
nanotechnologies?
b) Fromtheirperspective,howcantheprecautionaryprinciplebemadeoperational?
Aswillbeexplainedinsections1.3and1.6thereisempiricalevidenceforhazardsandrisks
of nanomaterials but this evidence does only allow in a very limited number of cases to
derivehealthbasedoccupationalexposurelimits(HBͲOELs).ThishastriggeredunconvenͲ
tional approaches to safeguarding the workplace characterized by potential exposure to
nanoparticles.OneoftheseapproachesessentiallysubstitutesHBͲOELsbynanoreference
values(NRVs).Thisapproachisdiscussedinchapters3Ͳ6.Anotherapproachmakesuseof
controlbanding.Thisapproachisdiscussedinchapter6.
2. Downstreamuseofnanomaterials
Workersalongthefulllifecycleofnanomaterialsareinvolvedinhandlingandprocessing
nanomaterials, but ignorance about the type of nanomaterials used in products, their
potentialreleaseduringuse,aswellasthelimitedknowledgeaboutthehazardsofMNMs
mayhindermakingafullriskassessmentandtodevelopanacceptableriskmanagement.
These issues are elaborated in a pilot in the construction industry, which described in
chapter3ofthisthesis.Thefollowingquestionswereraised:
a) WhichnanoͲenabledproductsareusedintheEuropeanconstructionindustry?
b) Are employers and employees aware of the nanoparticulate character of those
productsandofitsimplicationsforoccupationalhealth?
c) What are actual exposures to nanoparticles in a limited number of working
environmentswhereworkersdealwithnanoproducts?
d) How do these exposures compare with preliminary nano reference values for
workplaceexposurebasedonaprecautionaryapproach?
In an epilogue to this chapter (3.2 and 3.3) the discussion of the downstream use of
nanomaterialsisextendedtothefurnitureindustryandthepaintvaluechain(includingcar
repairandpaintingcontractors).
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3. Assessmentoftheusefulnessofprecautionarynanoreferencevalues
ToassesstheprovisionaltoolofnumberͲbasednanoreferencevaluesastudywassetupto
applythematworkplacesusingnanoparticlesinsettingsastheyoccurinpractice.Airborne
nanoparticles’ concentrations were measured and compared with nano reference values.
ThisapproachwascomparedwiththegenericapproachproposedbyPauluhn[2010]and
with the massͲbased approach as proposed by the British Standard Institute (BSI 2007].
Theseissueswereelaboratedfurtherinchapter4.Thefollowingquestionswereraised:
a) What is the actual exposure to NP during the use of nanomaterials in different
occupationalsettings?
b) IstheconceptofNRVsausefultoolforriskmanagementinindustrialsettings?
c) HowdoestheNRVͲconceptcomparetotheoverloadͲbasedapproachasproposedby
Pauluhn[2010]andthemassͲbasedapproachasproposedbyBSI[2007]?
4. Lessonslearnedfromthediscussionandexperiencewithnanoreferencevalues
TheintroductionofanewprecautionͲbasedriskmanagementtoolliketheNRVmaynotgo
without opposition. Therefore a study was set up involving companies using MNMs and
regulators in the Netherlands with the aim to get insight into the acceptance of the NRV
benchmarks,aswellasintotheuseoftheseNRVsasavoluntarytooltominimizeexposure
attheworkplace.Questionsraisedwere:
a) WhatcanbelearnedfromthediscussionaboutandexperiencewithNanoReference
ValuesintheNetherlandstominimizeexposuretonanomaterialsattheworkplace
effectively?
b) Underwhichconditionsarecompaniesthatproduceandusenanomaterialsableand
willingtoapplytheNRVs?
c) IsthevoluntarynatureofNRVsacceptable?
Chapter5seeksanswerstothequestionsraised,anddrawsconclusionsabouttheusability
ofNRVsasriskmanagementtooltominimizeexposuretonanomaterialsattheworkplace
and regarding the potential to apply the NRVs as an instrument that can be used on a
voluntarybasis.
5. Comparisonofriskmanagementtoolstosupportsafeworkingwithnanomaterials
Chapter 6 seeks to compare risk estimates and control measures that emerge from
applying the laymenͲoriented guidance for working safely with nanomaterials and two
nanoͲspecificControlBandingtoolswiththestrategytomeasureworkplaceconcentrations
and refer these with nano reference values (NRV). The matter of processͲgenerated
nanoparticlesandwhethertheseshouldbetakenintoaccountinriskmodelingisdiscussed.
Questionsraisedare:
a) DoMNMͲspecificCBtoolswhenappliedatthesameworkplacesleadtosimilarrisk
estimates for control measures and how do these relate to measured
concentrations?”
b) Is it legitimate to ignore PGNPs in risk assessment and risk management when
assessingMNMs?”
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A Definition for Nanomaterials
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6. ReflectionontheprecautionaryapproachusingNRVsinaninternationalcontext
TheprecautionaryapproachofNRVswasreflectedataninternationalforumofsmallͲand
mediumͲsizeenterprises(SMEs),largecompanies,tradeunions,governmentalauthorities,
research institutions, and nonͲgovernmental organizations (NGOs) from many European
countries, USA, India, and Brazil. The approaches towards risk management of
nanomaterialswithinsufficienthazarddataandopinionsoftheparticipantsabouttheNRVͲ
conceptarefurtherelaboratedinchapter7.Thefollowingquestionswerediscussed:
a) AreprecautionͲbasedNRVsforMNMsusefulandacceptableasasubstituteforHBRͲ
OELsandderivednoͲeffectlevels(DNELs)?
b) ArethemetricsasusedintheNRVusefulformeasuringNPs?
c) IsitadvisabletocombineexposureassessmentofMNMsandPGNPs
d) Whatistheopinionaboutapplyingtheprecautionaryprincipleinriskassessment?
e) How should a workplace deal with the lack of information regarding MNMs in
products?
f) Isitappropriatetousesoftregulationforexposurecontrol?
7. Generalconclusions
Thestudyendswithdrawinggeneralconclusionsinchapter8.
Thisintroductionfurtherhighlightsafewtopicsthatare(orshouldbe)inthefrontlineof
thediscussiononthesafeuseofnanomaterialsinpractice.Thefirsthighlight(section1.2)
concerns the definition of nanomaterials, which is object of an ongoing debate regarding
the purpose of defining nanomaterials exactly, being for legislative purposes for the
industry e.g. for registration of the materials they market, or for the purpose of risk
identification. The second highlight (section 1.3) regards the potential adverse effects of
nanomaterials,whatisknownandwhatshouldbeknowntobeabletomakeareliablerisk
assessment. Section 1.4 reflects on the precautionary principle and the role this principle
has in risk management. The fourth highlight (section 1.5) regards the background
nanoparticles with a ‘natural’ origin and nanoparticles that might be formed at the
workplacebyprocessesandequipmentused:theprocessͲgeneratednanoparticles.Sofar
this anthropogenic source is largely outside the debate on nanotechnologies, but
argumentsarebroughtforwardtoincludethissourceaswellinriskassessment.Section1.6
finally discusses the definition and scope of occupational exposure limits and derived noͲ
effectlevelsinEuropeandprecautionaryapproachestostandardsetting.
1.2
Adefinitionfornanomaterials
A
nessentialelementtostructurethedebateonnanotechnologiesistodefinewhat
wearetalkingaboutwhenreferringtonanoparticlesandnanomaterials.Overthe
past decade there has been a considerable global effort to develop a suitable
robustandcomprehensivedefinitionthatallowsthecharacterizationofnanomaterialsso
astofacilitatescientificand,moreparticularly,regulatoryandlegislativediscussionsand
agreement.ForregistrationofsubstancesundertheREACHlegislationaunivocaldefinition
for nanomaterials is needed, especially to distinguish whether new materials that are
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marketedshouldbeconsideredasnanomaterialsorshouldbeconsideredtofallunderthe
definition of existing substances. Arguments were brought forward concerning sizeͲ and
surfaceͲ oriented definitions regarding statistical limitations of particle number size
distributions(Lidèn2011)andregardingthehazardsofnanomaterialsbeingnotlimitedto
numberandsizeonly,butbeingaffectedaswellbydifferentotherfactorslikeporosityand
chemistry (Maynard 2011). Maynard states that a ‘one size fits all’ definition of
nanomaterials will fail to capture what is important for addressing risk. He warns for
sciencetobepushedasidewhenpolicyͲmakerswouldrestricthealthpolicytolimited,but
clearnanoͲregulations.Scenihr(2010)stressedthat“nanomaterial”isacategorizationofa
materialbythesizeofitsconstituentpartsanddoesnotimplyaspecificrisk,nordoesit
necessarily mean that this material actually has new hazard properties compared to its
constituents. However, size will influence biodistribution (and distribution kinetics) in an
organismorinanecosystem.
TheJointResearchCentreoftheEuropeanUniongaveanoverviewofcurrentdefinitions
andapproaches(Lövestametal2010)andconcluded thatfor pragmaticreasonsandfor
thesakeofuniqueness,broadness,clarityandenforceability,itwasjustifiednottoinclude
propertiesotherthansizeinabasicdefinition.Forspecificpurposesitmighthoweverbe
relevanttoadaptthegeneraldefinitionbyincludingotherpropertiesaswell.
The European Commission (EC) published its recommendation for a definition of
nanomaterials in October 2011 (EC 2011) (box1). Its considerations are clarified in an
accompanyingQuestionandAnswersdocument(EC2012).Areviewisforeseenby2014in
thelightofexperienceandofscientificandtechnologicaldevelopmentswithaparticular
focus on whether the number size distribution threshold of 50 % should be increased or
decreased.
Box1TheEuropeanCommission’sdefinitionofnanomaterials
‘Nanomaterial’means anatural,incidentalormanufacturedmaterialcontainingparticles,inan
unboundstateorasanaggregateorasanagglomerateandwhere,for50%ormoreofthe
particlesinthenumbersizedistribution,oneormoreexternaldimensionsisinthesizerange1
nmͲ100nm.
Inspecificcasesandwherewarrantedbyconcernsfortheenvironment,health,safetyor
competitivenessthenumbersizedistributionthresholdof50%maybereplacedbyathreshold
between1and50%.
Intheabsenceofbetterargumentsforotherthresholds,theCommissiondecidedtofollow
themostcommonlyappliedapproach,i.e.asizerangebetween1and100nm.
ThedefinitionoftheEuropeanCommissionisintendedforuseasreferenceforlegislative
and policy purposes in the EU and does not define boundaries for occupational or
environmentalrisks.TheECarguesthataspecifichazardsorrisksofthenanomaterialwill
only become clear as a result of a risk assessment. Another reason for not referring to
properties specific to nanomaterials is legal clarity. The specific properties of (different)
nanomaterialsvaryanditisoftenunclearwhethersuchpropertiesrelatetothenanoͲsize,
to the chemical nature of the material or a combination of both. Nevertheless the
Commissionmakesanimplicitreferenceto potentialrisksbystatingthatit mayinsome
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A Definition for Nanomaterials
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cases be necessary to include additional materials, such as some materials with a size
smallerthan1nmorgreaterthan100nminthescopeofapplicationofspecificlegislation
orlegislativeprovisionssuitedforananomaterial.
Proposalsfora higher upperͲlimit inthe definitionof nanomaterials>100nmwere made
byenvironmentalNGOs(EEBndͲa).TheEEBproposesarangeof0.3Ͳ300nmtoallowthe
definition to capture as much material as possible about which there is already concern.
An upperͲlimit of 300nm was also suggested by the German Advisory Council on the
Environmentforprecautionaryreasons(SRU2011)andearlierbyScenhir(2009).
SomescientistssuggestanupperͲlimitlowerthan100nmwhenthefocuswouldbe
solelytoidentifynanoͲeffects.Auffanetal(2009)suggestedthatnanoparticleslargerthan
about 30 nm do not in general show properties that would require regulatory scrutiny
beyondthatrequiredfortheirbulkcounterparts.Auffanetal.(2009)alsosuggestedthat
thereisacriticalsize,whichisstronglyrelatedtotheexponentialincreaseinthenumber
of atoms localized at the surface as the size decreases and delineates a smaller set of
nanoparticles,typicallywithdiameterslessthan20–30nmandshowingasizeͲdependent
crystallinity.Choietal(2011)haveshownthattherearemajordifferencesintranslocation
ofnanoparticlesfromthelungsintothebodyatnanoparticlesizeswellbelow100nm.Pan
etal(2007)showedgoldnanoclusters(1.4nm)tobetoxictocellsowingtotheirspecific
interaction with major grooves of DNA, whereas smaller or larger gold particles did not
behaveinthisway.
The EC definition regards ‘natural’, ‘incidental’ and ‘manufactured’ nanomaterials.
The starting point is to consider primary particles including particles in agglomerates or
aggregateswhenevertheconstituentparticlesareinthesizerange1nmͲ100nm.AsdeͲ
fined by the EC, nanomaterials are not exclusively synthesized (manufactured or engiͲ
neered) nanomaterials. The term nanomaterials also covers particles originating from
natural processes and originating from heating and combustion processes (incidental
nanoparticles), and assemblies of these with manufactured nanomaterials and nonͲ
nanoparticulatepollutants.Inthepartofthisthesis,whichfocusesonworkplaceexposure
the incidental nanoparticles are called processͲgenerated nanoparticles (PGNP). The EC
notesthatnanoparticlesarepresentinlowquantitiesinmostsolidmaterialsandthatthe
percentage may be significant in certain powders. Their choice for the 50% number size
distributionmayrefertothisphenomenon,anditwillbesubjecttofurtherreview.RegardͲ
ingpotentialrisksitmustbenotedthatathresholdforthenumbersizedistributionof50%
innanomaterialsdoesnotguaranteethegeneratedairbornenanoparticles’concentration
to remain within safe limits when using products that contain nanomaterials (Weir et al
2012).Nanoparticleshaveahighpotencytobecomeairborne,whichismainlydetermined
by the handling procedures, also in batches with a concentration of <50%(p/p) (van
Broekhuizen et al 2012). Additionally, the RIVM (Bleeker 2012)noted that it agrees with
theCommission’sprinciplethatananomaterialshouldnotautomaticallybeconsideredas
hazardous, but conversely, materials not covered by the definition should not automatiͲ
callybeconsideredassafe.SuchmaterialsmayposeananoͲsizerelatedrisk,ifasubstanͲ
tialnumberoftheparticlesisinthenanoͲsizerange,dependingonthedegreeofhuman
andenvironmentalexposure.
RegardingtheuseofnanomaterialsinproductstheECnotesthatifananomaterialisused
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amongstotheringredientsinaformulationtheentireproductwillnotbecomeananomaͲ
terial. With this explanation the EC proposes to strongly limit the use of the wording
“nanoproduct”.
In sum the recommendation of the European Commission for a definition of
nanomaterials has an explicit legislative and policy orientation, and contains some eleͲ
mentsregardingrisksofnanomaterials.Underthedefinitionthebackgroundand‘incidenͲ
tal’nanomaterialshavetobetakenintoaccount.Risksinthepracticeofthedownstream
user using nanomaterialͲenabled products have to be considered by specific risk
assessments that take into account the release of MNMs during the handling of the
productsandtheNMsthataregeneratedattheworkplacebytheequipmentandtheuse
ofconventionalbulkmaterials.
GiventheECdefinitionandexistinglegislationsuchastheChemicalAgentsDirective(CAD
1998)andinREACH(EC2006)themanufacturerandsupplierhavetoprovideinformation
aboutthepotentialreleaseofMNMsandtheassociatedrisksduringintendeduse.ItreͲ
mainsquestionablewhetherthemanufacturerortheOEM(originalequipmentmanufacͲ
turer)hasaresponsibilityaswelltoinformthedownstreamandenduseraboutthepossiͲ
blereleaseofPGNPsduringtheintendeduseofhisequipment.
This thesis considers nanomaterials in accordance with the ECͲdefinition within the sizeͲ
rangeof1Ͳ100nm.However,whenmeasurementsarecarriedout,thedetectionlimitsof
the measuring equipment of 10Ͳ300nm are used, taking into account the likeliness that
assembliesareformedattheworkplacethatmayhavealargerdiameterthat100nm.
1.3
AdverseeffectsofNanomaterials
W
hen released in the workplace or in the environment nanoparticles may be
potentially dangerous. The lung, skin, gastrointestinal tract, nasal olfactory
structures, and eyes are the major portals through which nanoparticles can
enterthebodyasaresultofoccupationalorenvironmentalexposures(Bormetal2006).
After exposure the nanoparticles could translocate into the blood and lymph circulating
systemandtraveltodistantorgansincludingthecardiovascularsystemandbrain(Neletal
2006,Choietal2010).Ofprimaryconcerninoccupationalsettingsareinhalationandskin
exposure.Sofarthehealthyskinhasshownlittlepenetration,yetthereareseveralstudies
thatpointattheconditionoftheskin(barrierintegrity,anatomicstructure,skindiseases
suchasallergicandirritantcontactdermatitis,atopiceczema,psoriasis)thatmayinfluence
uptake (MonteiroͲRiviere et al 2012). On the other hand, calcium carbonate and calcium
phosphateNPswereshowntobeabletoinhibitskinpenetrationofnickelions(Vermulaet
al2011).InhalationisthemostrelevantexposurerouteofMNMsandthelungsandpleura
the major primary targets for adverse effects (Donaldson et al 2012). Larger particles
deposit higher up in the nose and upper respiratory tract, while only the smaller size
particles deposit in the more peripheral bronchioles and proximal alveolar region
(Donaldsonetal2012).Theinhalationdepositionprobability,asafunctionoftheparticles’
diameterisrepresentedinfigure1,showingthattheparticlesatthenanosize(between1
16
Adverse Effects of Nanomaterials
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–– 100nm) havve the higheest probabiliity to depossit in the alvveolar region
n. Deposition
n may
in
ncreasefurth
herwithexercise,toadeegreegreate
erthanthatp
predictedbyymodeling(D
Daigle
etal2003).
Figure1
Inhalation
ndeposition
nprobabilityy(fromICRP1994)
Leegend: The grraph shows thaat nanoparticlees with a size between 10 and
a 100nm dep
posit primarily in the
alveolaarregion(yello
owline),while smallerparticu
ulatesandlargeermaydeposittinthetracheo
oͲbronͲ
chialreegion(bluelinee),ortheupperrairways(redline).NP=diameeterrangeofnanoparticles
In
n the lungs several cleaaring mechanisms are active. In thee upperͲairw
ways particle
es are
trrappedinthemucusand
dremovedupwardsbyth
hemucociliaaryescalatortothethroaatand
sw
wallowed. In
n the terminal bronchio
oles and alvveolar region the cleariing mechaniism is
predominantlybymacrop
phageaction
n(Donaldson
n2012).
W
When
nanom
materials aree deposed in
n the lungs other organ
ns may also be affected. One
possibilityistthatnanomaaterialstransslocatefrom
mthelungsin
ntothelymp
phaticandcirculaͲ
ory systems. Choi et al (2011) dem
monstrated in rat modeels that nan
noparticles with
w
a
to
hydrodynamicdiameter((HD)lessthaanу34nmtrranslocateraapidlyfromtthelungtolymph
m
factor determining the
nodes, whilee below thiss size the surface charge is a major
trranslocation with dipolaar, anionic or nonionic surfaces beeing permissive and caationic
su
urfacesbeingrestrictive.Theydemo
onstrateasw
wellthatnanoparticlesw
withaHD< 6nm
andadipolarsurfacechargecantransslocaterapid
dlyfromthelungstolym
mphnodesan
ndthe
bloodstream, and can bee subsequenttly cleared by
b the kidneeys. Choi et aal. (2011) su
uggest
hat the smaaller nanoparticles, with a HD у5 nm
m are of concern for caarcinogenesiis and
th
distal inflammation beccause they are capablle of traveling from tthe lung to
o the
dstream, the
ey can poten
ntially reach every tissue and
bloodstream, and once in the blood
009) show th
hat iridium and
a carbon primary parrticles,
organ in the body. Kreyliing et al (20
heiragglomeeratesandagggregateswiithasizebettween20and80nm(and
daprimaryssizeof
th
<10nm)arefo
ound24hafttertranslocaationfromth
helungtothebloodcircu
ulationinthe
eliver,
pleen,kidneys,heart,an
ndbrain,andinthesoftttissueandbo
one.
sp
17
__________________________________________________________________________________
Other possibilities are that inflammation of the lungs triggers the release of metabolic
stressorsandplateletͲleukocyteaggregateswhichmightaffectotherorgansandthatthere
isanimpactonactivityoftheautonomousnervoussystem(Reijnders2012).
Epidemiologicalstudieshaveassociatedexposuretoambientnanoparticleswithsystemic
effects,such ascardioͲvascular diseases(Simkoetal.2010,Brooketal2010),whichisa
reasontoinvestigatethisissueforMNMsaswell(Colognatoetal2012).
Ofinterestisalsotheexposurerouteviathenoseandtheolfactorynervethatmay
give direct access to the brain. Elder et al (2006) found in inhalation experiments with
nanoͲMnOinratsahigheraccumulationoftheseparticlesintheolfactorybulbthaninthe
lungs,andfoundincreasedlevelsofMninthebraintissue.Theauthorsconcludedthatthe
olfactoryneuronalpathwaymightbearelevantexposureroutesubsequenttoinhalation
forMnoxidenanoparticlesalsoinhumans.Savolainen (2010)suggests that theseobserͲ
vationsareofspecialimportancebecausethedoseswerelowtomoderate,andbecause
thetranslocationpathwaywasintraneuronal.
An overview of possible mechanisms by which nanomaterials might react with
biologicaltissuewasgraphicallyrepresentedbyNeletal(2006)seefigure2.
Figure2
Possible mechanisms by which nanomaterials interact with biological tissue (from Nel et al
2006).
Tounderstandpossibleadverseeffectsofnanoparticlesitisimportanttounderstandthe
nanoͲbiointerface,inwhichthenanoparticles’surfaceandtheinteractionsbetween the
MNM and biomolecules play an essential role (Nel et al 2009). Most important for the
18
___________________________________________________________________________________
nanoparticless’ surface properties
p
a
are
the maaterial’s cheemical composition, su
urface
unctionalizattion, surfacee charge, sh
hape and angle of curvvature, poro
osity and su
urface
fu
crystallinity, heterogeneiity, roughneess, and hyd
drophobicityy or hydroph
hilicity (Nel et al
d they are coated
2009). When nanoparticles enter the blood, plaasma or inteerstitial fluid
w
with
proteinss, the nano
oparticle–pro
otein coronaa. The corona is of further significance
becauseitinffluencesthe surfacepropertiesofth
heparticlean
ndthehydro
odynamicsizzeand
hanges in re
eaction with proteins in
n the surrou
unding
iss subject to continuous dynamic ch
m
medium.
It influences association, dissociation and exchan
nge of elem
ments (Savollainen
2010). d high adso
orption by the
t
smaller nanoparticcles is
The high reactivvity of, and
r
at th
he surface of
o the particlle. A nanopaarticle
explained by the numberr of atoms residing
w
withadiamet
terof300nm
mhas5%ofitsatomsatthesurfaceoftheparticcleand50%when
th
he diameterr is 30nm (C
Colognato ett al 2012). Thermodyna
T
mic analysiss reveals thaat the
su
urface tensio
on decreasees with decreeasing particcle size as a result of th
he increase in
i the
potentialeneergyofthebulkatomsofftheparticle
es.Smallerp
particleswith
hincreased molar
bmoleculeso
orionsperu
unitareaontotheirsurfaacesin
frreeenergyaremorepronetoabsorb
ordertodecreasethetotalfreeenerggyandtobeccomemoresstable.Henceadsorption
nonto
mallerparticcleshasahiggheradsorptioncoefficie
ent(Zhangettal1999).
sm
Figuree 3 indicates potential interaction
ns of MNM
M with cellss and subce
ellular
sttructures.
Fiigure3. Possibleinteraction
nsofMNMswiiththecelland
dsubcellularstrructures.
Sugggested mechaanisms underlying nanoparrticleͲinduced
d responses aat the cellularr level,
whicch, in sufficieently high or persistent le
evels, potentiially can lead
d to, altered tissue
funcction.(FigureffromColognatoetal2012)
M
Muchisstillu
unknown,bu
utitiscleartthatnanomaaterialsarelikelytointerferewithce
ellular
organization andaffectbiologicalfunctionsinwaaysthatcann
notbededuccedfrompre
evious
w macroͲ or
o microsizeed particles (Kagan
(
et al 2010).

experience with
19
__________________________________________________________________________________
ȋȌǦ
Ǥ Oxidativestress,whichiseffectedbytheinitiationandpropagationoffree
radical oxidation reactions and excessive accumulation of their products, is one of the
mostprominenteffectsassociatedwiththeadverseeffectsofnanomaterials(Shvedovaet
al 2010). Oxidative stress is defined as an imbalance between oxidants and antioxidants
inside cells, in lung lining fluid or tissue fluid, such that there is more oxidation. ROS are
produced by particles themselves by chemical reactions and by cells as part of normal
respiration.Excessiveoxidativestresshasbeenproposedasacommonparadigmforthe
toxicities of engineered nanoparticles (Shvedova et al 2010). Many studies support this
hypothesis(seeforexampleFadeeletal2012,Reijnders2012).ForexampleforthelowͲ
toxic, fineͲ and nanoͲTiO2 it was shown that local persistence in the lung may lead to
chronic inflammation and may cause nonͲgenotoxic induction of lung tumors in rats
(NIOSH2011).Therearehoweveralsocontradictingstudiesthatfindnodirectcorrelation
betweenROSproductionandcelltoxicity(Diaz2008).
The form of nanomaterials is an important issue in hazard and risk assessment. Carbon
nanotubes (CNT) were shown to be able to induce asbestosͲlike alterations in the mesoͲ
theliumofthemouseperitonealcavity(Polandetal.,2008)andincreasethelikelihoodof
mesotheliomas in sensitive mouse strains (Takagi et al., 2008). Long CNTs may give an
acuteinflammationleadingtoprogressivefibrosisofthepleura,whilethisisnotthecase
forshortCNTs(Murphyetal.2011).BasedonthistypeoffindingsSCENIHR(2009)advises
toconsiderthepossibilitythatfreefibers,rodsandtubesthatarechemically/biologically
persistent, are rigid and have a high aspect ratio (i.e. μm in length and nm in diameter)
mayhavesimilarpropertiestoasbestos.
Nel et al (2009) summarized the mechanisms of nanomaterial cytotoxicity of difͲ
ferent nanomaterials (see table 1). A general overview of effects as the basis for pathoͲ
physiologyandtoxicityisgivenintable2.
Table1
Summarynanomaterialcytotoxicity(fromNELetal2009)
Nanomaterial
TiO2
Cytotoxicitymechanism
ROSproductionmediatedbyelectron–holeͲpairs
Glutathionedepletionandtoxicoxidativestressasaresultofphotoactivityandredoxproperties
NanoparticleͲmediatedcellmembranedisruptionleadtocelldeath;proteinfibrillation
ZnO
ROSproduction
Dissolutionandreleaseoftoxiccations
LysosomaldamageInflammation
Ag
DissolutionandAg+releaseinhibitsrespiratoryenzymesandATPproduction
ROSproduction
Disruptionofmembraneintegrityandtransportprocesses
AuNPsandnanorods
Disruptionofproteinconformation
CdSe
DissolutionandreleaseoftoxicCdandSeions
SiO2
ROSproductionbysurfacedefectsandimpurities
Proteinunfolding
Membranedisruption
Fe3O4
ROSproductionandoxidativestress
2+
LiberationoftoxicFe Disturbanceoftheelectronicand/oriontransportactivityinthecellmembrane
20
___________________________________________________________________________________
Nanomaterial
CeO2
Cytotoxicitymechanism
Proteinaggregationandfibrillation
MWCNT
SWCNTandMWCNT
FrustratedphagocytosiscauseschronictissueinflammationandDNAoxidativeinjury
GenerationofROSduetothemetalimpuritiestrappedinsideCNTs
ProͲinflammatoryeffectsduetooxidantinjury
GranulomatousinflammationduetohydrophobicCNTaggregationInterstitialpulmonary
fibrosisduetofibroblastͲmediatedcollagenproduction
Fullerenes
ROSproduction(spontaneousorphotoactivated)Hydrophobicsurfaceincreasesaggregationbut
promotesintramembranouslocalization
Cationicnanospheres
anddendrimers
Membranedamage,thinningandleakage
Damagetotheacidifyingendosomalcompartmentbytheprotonspongeeffectthatallowsentry
intothecytosol
Liberationoftoxiccations
Co/NiferriteNPs,
magneticmetallicNP
Al2O3
Cu/CuO
ROSproductionProͲinflammatoryresponse
DNAdamageandoxidativestress
MoO3
Membranedisruption
Table2
NMeffectsasthebasisforpathophysiologyandtoxicity(fromNel(2006)).
Effectssupportedbylimitedexperimentalevidencearemarkedwithasterisks*;effectssupported
bylimitedclinicalevidencearemarkedwithdaggers†.
ExperimentalNMeffects
Possiblepathophysiologicaloutcomes
ROSgeneration*
Protein,DNAandmembraneinjury*,oxidativestress†
Oxidativestress*
PhaseIIenzymeinduction,inflammation†,mitochondrialperturbation*
Mitochondrialperturbation*
Innermembranedamage*,permeabilitytransition(PT)poreopening*,energy
failure*,apoptosis*,apoͲnecrosis,cytotoxicity
Inflammation*
Tissueinfiltrationwithinflammatorycells†,fibrosis†,granulomas†,atheroͲ
genesis,†acutephaseproteinexpression(e.g.,CͲreactiveprotein)
UptakebyreticuloͲendothelialsystem*
Asymptomaticsequestrationandstorageinliver*,spleen,lymphnodes†,possiͲ
bleorganenlargementanddysfunction
Proteindenaturation,degradation*
Lossofenzymeactivity*,autoͲantigenicity
Nuclearuptake*
DNAdamage,nucleoproteinclumping*,autoantigens
Uptakeinneuronaltissue*
Brainandperipheralnervoussysteminjury
Perturbationofphagocyticfunction*;
‘‘particleoverload,’’mediatorrelease*
Chronicinflammation†,fibrosis†,granulomas†
Endothelialdysfunction,effectson
bloodclotting*
Atherogenesis*,thrombosis*,stroke,myocardialinfarction
Generationofneoantigens,breakdown
inimmunetolerance
Autoimmunity,adjuvanteffects
Alteredcellcycleregulation
Proliferation,cellcyclearrest,senescence
DNAdamage
Mutagenesis,metaplasia,carcinogenesis
Interferenceinclearanceofinfectiousagents†
In sum: based on (still limited) experimental animal and cell tissue studies with
MNMs and epidemiological studies on the effects of airborne particulate pollutants it is
likelythatexposuretoMNMsmayleadtoadversehealtheffects.Oxidativestressleading
to inflammation is likely one of the key mechanisms exhibited by many nanoparticles of
21
__________________________________________________________________________________
differentsize,chemical compositionandform.Asa resultofprolongedhighexposureto
morereactiveNPsoxidativestressmaygiverisetoanongoinginflammation,whichislikely
to worsen bronchitis or asthma in those who already have a lung disease and even may
causelungfibrosis.OngoinginflammationorgenotoxiceffectsofreactiveNPcouldleadto
lungcancerifexposuresarehighenoughandforaprolongedperiod.AsbestosͲlikeeffects,
includingmesotheliomamightbeexpectedfromexposuretorigid,chemically/biologically
persistent free nanofibers with a high aspect ratio (length >20 μm). Also there might be
effectsofnanoparticlesonotherorgans.Savolainenetal(2010)emphasizethatavailable
observations on the toxicity of manufactured nanoparticles and the early stage of risk
assessmentwithalackofdatajustifiesapplyingaprecautionaryapproachinassessingthe
risksofmanufacturednanomaterials.
1.4
PrecautionaryPrinciple
T
hePrecautionaryPrincipleemergedataworldwidepolicyforumin1992attheUN
Conference on Environment and Development in the Rio Declaration on
EnvironmentandDevelopmentincludedinprinciple15amongprinciplesofgeneral
rightsandobligationsofnationalauthorities(UNEP1992)(seebox2).Itwaslaunchedasa
principletoprotectagainstadverseeffectstotheenvironment,butitshouldnotbeseen
as restricted to the environment. The scope of its applicability is much broader and
includesoccupationalhealthandconsumersafety.
Box2
RioDeclaration,principle15:PrecautionaryPrinciple
Wheretherearethreatsofseriousorirreversibledamage,lackoffullscientificcertaintyshall
notbeusedasareasonforpostponingcostͲeffectivemeasurestopreventenvironmental
degradation.
The PP is a deliberative principle and, as von Schomberg (2006) notes, its application inͲ
volvesdeliberationonarangeofnormativedimensions,whichneedtobetakenintoacͲ
count while making the principle operational in the public policy context. These regard
issuessuchaswhentoinvoketheprecautionaryprinciple(actratherthannottoact),the
level of protection aimed at, a costͲbenefit analysis balanced with health considerations,
theburdenofproofofadverseeffectsandthetiming,theproportionalityofprecautionary
actions, deliberation about uncertainties and lack of knowledge, the seriousness of
possibleadverseeffects,andwhatleveltouseasprovisionalstandard.Theprecautionary
principle is subject to extensive debates and is frequently reformulated as to make it
better comprehensible. It is used as basis in many European Directives and International
treatiesandissubjectofrulingsoftheEuropeanCourtofJustice(VonSchomberg2006).
A significant policy document relating to the precautionary principle is the 2000
Commission Communication on the Precautionary Principle (EC 2000). While this docuͲ
ment does not have a legally binding status, it provides a comprehensive EU level policy
guidance on the application of the principle and provides insights into issues relating to
boththescopeoftheprinciple’sapplicabilityin EUlaw,aswell asintoconditionsforits
invocation. TheEuropeanCommissiondoesnotprovideadefinitionfortheprecautionary
principle.Neverthelesstheynoteintheircommunicationthattheprecautionaryprinciple
22
Precautionary Principle
___________________________________________________________________________________
applies under defined conditions (box 3), but in view of ongoing discussions on the
philosophy behind the principle, its interpretations and its nonͲstrictly binding character
there is room to make the principle operational into a precautionary approach for
industrialpractice:
Box3
ApplicationoftheprecautionaryprincipleaccordingtotheEuropeanCommission
Theprecautionaryprincipleapplieswherescientificevidenceisinsufficient,inconclusiveor
uncertainandpreliminaryscientificevaluationindicatesthattherearereasonablegroundsfor
concernthatthepotentiallydangerouseffectsontheenvironment,human,animalorplant
healthmaybeinconsistentwiththehighlevelofprotectionchosenbytheEU.
IntheCodeofConductforResponsibleNanosciencesandNanotechnologiesResearchthe
European Commission emphasizes the importance of conducting research activities in
accordance with the precautionaryprinciple, anticipatingpotentialenvironmental,health
and safety impacts of nanosciences and nanotechnologies and taking due precautions,
proportional tothelevel ofprotection,whileencouragingprogressforthe benefitofsoͲ
cietyandtheenvironment( ʹͲͲͺȌ.Invokingtheprecautionaryprincipleinmatters
regardingthedevelopmentofnanotechnologiesanduseofmaterialsmanufacturedwith
thesetechnologiesisacceptedbymanyofparticipantsindiscussionsexplicitlyaddressing
themattersofhazardandrisk(SwissRe2004;GR2006;WWR2008,SER2009,EC2010).
Governments advocate applying the precautionary principle whenever uncertainties and
ambiguities are at stake when using nanomaterials (EC CoC 2008, SRU 2011, Gans et al
2012). Several industrial participants have publicly given notice of their intentions to
contribute to a responsible development of nanotechnologies but do not refer to the
precautionary principle. They include the control of risks in Codes of Conduct (Dupont
2007,Bayer2007,BASF2008,PACTE2008,Evoniknd)orrefertotheircommitmenttothe
Responsible Care Initiative (CEFIC 2011). Industrial stakeholders acknowledge the large
uncertaintiesandambiguitiesregardingtherisksofmanufacturednanomaterialsandshow
awarenessthatthecollectionofhazardandexposuredataofthenanomaterialsuseddoes
notkeeppacewiththerapiddevelopingtechnologiesandthemarketingofnanoproducts
(NanoCap2009,thisthesischapter5).Howeverthemeaningoftheprecautionaryprinciple
asperceivedbythoseinindustrymaybevariable.Hellandetal(2008)concludefromtheir
studyintheSwissindustryusingMNMsthatthatindustrydidnotconveyaclearopinionas
towhoshouldberesponsibleformanagingthepotentialenvironmentalhealthimpactsor
how to regulate NPMs throughout their life cycle. They note that industry does not
necessarilyseemonitoringanddemonstratingspecificcharacteristicsofirreversibility asits
responsibility. Engeman et al (2012) demonstrated that despite the reported uncertainty
and perceived risk regarding MNMs (which should motivate to apply a precautionary
approach), companies reported preference for autonomy from government regulation,
andamajorityof58%agreedthatworkersareultimatelyresponsiblefortheirownsafety
at work. Jostman (2007), Executive Director of the Programme Product Stewardship of
CEFIC (European Chemical Industry Council) has invoked scientific uncertainty as reason
not to apply the precautionary principle. Such responses suggest ambiguous views on
responsibility and demonstrate tensions between the roles and the values of regulators,
industryleaders,industrialhygienists,andworkersincreatingasafeworkplace.
23
__________________________________________________________________________________
In order to apply the precautionary principle properly, it must be clear what is precisely
understoodby‘scientificuncertainty’andwhattypesofuncertaintiesarerelevantforthe
invocationoftheprecautionaryprinciple.VonSchomberg(2006)categorizesfourtypesof
uncertainties related to the state of affairs in science and the possible corresponding
responsesbyriskmanagement.
Table3
Overview of State of Affairs in Science and the possible corresponding responses by Risk
Management(sourcevonSchomberg2006)
Policy Framework/ Regulatory action/
Examples
Circumstances
StateofAffairsinScience
Risk
Knowneffects,quantifiableprobabilities,
uncertaintiesmayhavestatistical(e.g.
stochastically)nature
RiskManagementbydefiningthresholds
onthebasisofchosenlevelof
protection,exercisingprevention,
minimizationofriskandorprecautioͲ
nary**minimizationofrisksbyfeasible
managementmeasures:applyingthe
ALARAprincipleetc.
UnquantifiableRisk,
lackofknowledge
Knowneffects/unknownoruncertain
causeͲeffectrelations,therefore
unknownprobabilities
Antibioticsinfeedingstuff/Protectionof
theNorthSea.Invocationof
precautionaryprincipleisjustified;
preventivemeasurestotakeawaythe
possiblecausescanbejustified.
Epistemic
uncertainty:scientific
controversies,lackof
knowledge
Unknownscopeofeffects,however,
degreeandornatureoftheir
‘seriousness’(inrelationtothechosen
levelofprotection)canonlybe
estimatedinqualitativeterms.
Invocationoftheprecautionaryprinciple
isjustified:example:GMOs,Climate
Change,Ozonedepletion
Hypotheticaleffect/
imaginaryrisk
Argumentsonthebasisofafully
Invocationofprecautionaryprincipleis
conjecturalknowledgebase,noscientific notjustified.
indicationfortheirpossibleoccurrence
** Remark PvB: It would be better to use the wording “preventive minimization” instead of “precautionary
minimization”
Basedonhiselaborationsoftheprecautionaryprinciple,itsusebytheEuropeanCourtof
Justice,thebroadEUendorsementofEuropeanGuidelinesontheprecautionaryprinciple
and on International Treaties such as of the WTO and the UN, von Schomberg (2006)
proposes a definition to bring the precautionary principle in line with the growing
recognition of the normative challenges involved while invoking the precautionary
principle(seebox4).
24
Precautionary Principle
___________________________________________________________________________________
Box4. Policydefinitionoftheprecautionaryprinciple(vonSchomberg(2006))
Where,followinganassessmentofavailablescientificinformation,therearereasonable
groundsforconcernforthepossibilityofadverseeffectsbutscientificuncertaintypersists,
provisionalriskmanagementmeasuresbasedonabroadcost/benefitanalysiswhereby
prioritywillbegiventohumanhealthandtheenvironment,necessarytoensurethechosen
highlevelofprotectionintheCommunityandproportionatetothislevelofprotection,maybe
adopted,pendingfurtherscientificinformationforamorecomprehensiveriskassessment,
withouthavingtowaituntiltherealityandseriousnessofthoseadverseeffectsbecomefully
apparent.
Von Schomberg (2012) further elaborates on how the normative qualifier “reasonable
grounds”isrelevantforinvocationoftheprecautionaryprincipleandreferstothetypeof
circumstances as listed in table 3. It is the second and especially the third type of
circumstancesintable3thatgiverisetotheuseofprecautionaryprinciple.The‘qualityof
theinformation’relevanttotheprecautionaryprinciplerelatesespeciallytowhattypeof
informationisknownorshouldbeknownandofwhichinformationoneisignorant.Still,as
Rip (2006) remarks, this formulation of the precautionary principle is not immediately
applicable to nanotechnologies as broad umbrella term of enabling technologies. What
should be considered as ‘reasonable grounds’ remains unclear especially in case of
promisesandconcernsaboutnanotechnologies.Rip(2006)showsthattherearepossibiliͲ
ties for precautionary approaches even when the precautionary principle (as defined by
von Schomberg) cannot handle speculative technologies (where there is ignorance, not
just uncertainty). The PP can handle manufactured nanomaterials, in R&D, intended or
alreadyappliedinconcreteproducts,whichareonthemarket.
Againstthisbackgroundindiscussionsadistinctionshouldbemadebetweenthe
broad umbrella term “nanotechnologies”, for which no general adverse effects can be
assessed,andtermssuchas“nanoparticles”.Regardingthepositivestanceoftheinvolved
actorstowardsinvocationoftheprecautionaryprincipleindiscussionsbetweenindustry,
governmentsandCSOs,itseemsthatindustryactorsrefertothenanomaterialsastheyare
currentlyunderdevelopmentoronthemarket.
In sum, the precautionary principle has a deliberative nature and it is based on
normativequalifiers.TheprecautionaryprincipleisalsoafundamentalprincipleintheEU
legislativeframeworkandassuchitmaystimulateindustrialusersofnanotechnologiesto
formulateawayinwhichtheyintendtoapplythenovelnanomaterialsintheirproducts
and processes; the novel nanomaterials that lack the essential hazard data needed for a
reliableriskassessment.Asacomplementtoexistinglegislationindustrymayalsodevelop
codes of conduct to frame their responsible and sustainable approach towards
nanotechnologiesandoperationalizehowtheyintendtodealwithuncertain,ambivalent
human and environmental risks. The precautionary principle allows CSOs to give an
interpretationofnormativequalifiersusedfordefiningsafeandsustainablenanomaterials
and nanoproducts and to contribute to the formulation of a socially acceptable
precautionary approach. Transparency and openness, especially by the industry about
known,anduncertainrisksarekeyelementsinthis,includinginformationonwhereinthe
productionchainandbywhatuseofnanoproductsreleaseofnanomaterialsmightoccur.
Thisthesisappliesthedefinitionfortheprecautionaryprincipleasgiveninbox4.
25
__________________________________________________________________________________
1.5BackgroundconcentrationsandProcessͲGeneratedNanoparticles
A
mbient“background”nanoparticles
Nanoparticles (in many environmental studies denominated as ultrafine particles
(FP))arearoundusinourdailylifeasparticlesoriginatingfromnaturalprocesses
like volcanic activities, fires, and erosion processes and from anthropogenic sources as
traffic,smoking,heatingandcooking.Dynamicprocessesintheatmosphereplayaroleof
which agglomeration and aggregation (the formation of assemblies) are important
processes. In natural environments the formation of new particles is of importance, of
which the main mechanism is nucleation of lowͲvolatile gasͲphase compounds, followed
by their growth into small particles (Morawska et al 2008). The background of nanoparͲ
ticlesinambientairconsistsofamixtureofinorganicandorganicparticlesthatvariesin
(chemical)composition.Particlescomposedofsubstancessuchasmetaloxides,polycyclic
aromatichydrocarbons,oxidizedorganicstructures,sootinmanydifferentformsandsizes
may be present. Sources of ultrafine particles are abundant, but in urban environments
traffic,(especiallyemissionsfromdieselengines)maybedominating(MattiMaricq2007,
Morawska et al 2008). In urban centers in Finland concentrations up to 140.000
particles/cm3 were measured, while along highways number concentrations of
>60,000/cm͵ weremeasured(Husseinetal2005).Nanoparticleorultrafineparticle(UFP)
exposure for pedestrians in Leicester, UK was suggested to be up to 50% higher than in
cars(Gulliveretal2007);atcarparkingsinLeedsmeanUFPexposurelevelsofattendants
were reported up to 40,000 particles/cm3, while peak levels may be as high as 400,000
particles/cm3(Tiwaryetal2012).Dahletal(2006)identifiedthatduetoweartherubber
car tires emit significant amount of UFPs originating from the carbon reinforcing filler
material (soot agglomerates) and the plasticizers (mineral oils). Emissions from aircraft
engines were measured under varying conditions at concentrations from 700,000
nanoparticles/cm3upto > 5,000,000nanoparticles/cm3witha particles’ diametervarying
fromу10nmͲу30nm(EPA2009).
Theambientnanoparticlesmayinfluencetheindoornanoparticles’concentrations.
Van Broekhuizen et al (2012) (see chapter 4) measured mean indoor background
concentrations in Dutch industrial plants varying between 6,000 and 21,000
nanoparticles/cm3, with an occasional high mean concentration of 28,000 nanoparͲ
ticles/cm3.
Particlenumberconcentrationsincleanairinthehighmountainsweremeasured
in the Himalaya’s at a height of 4520m (above sea level) varying from 80 – 8,000
particles/cm3withameanat1150particles/cm3(Moorthyetal2011).
Cigarette smoking is another not processͲrelated anthropogenic source of
workplaceairbornenanoparticles.VanBroekhuizen(2011b)foundinasmokers‘roomofa
companynanoparticles’numberconcentrationupto>500,000particles/cm3Ǥ
Somebackgroundconcentrationsaresummarizedinfigure4.
26
Background Concentrations and Process Generated Nanoparticles
___________________________________________________________________________________
Figure4
Indicationofsome“environmental”backgroundconcentrations
Ultrafineparticles’concentrations(particles/cm3)
Airport
>700.000
Seriouslypollutedenvironment
>100.000
Highways
>60.000
Cleanairintown
<10.000
Cleanairmountains
у1.000
0
200.000
400.000
600.000
800.000
Sources:seeprevioustext
ProcessͲgeneratednanoparticles
Exposure assessment to MNMs in industrial workplaces shows that the handling of
nanomaterials and nanoͲenabled products may give rise to exposure to primary MNMs
andagglomerates(Brouwer2010),andsimultaneouslytonanoparticlesformedbyworkͲ
relatedprocesses.Thisthesiswillshowthatnanoparticlesgeneratedattheworkplaceby
processes and equipment used may even dominate the airborne nanoparticles’ number
concentration. Industrial processes (also conventional processes, without any relation to
nanotechnology and manufacturing or processing of nanomaterials) may generate airͲ
borne nanoparticles, sometimes up to levels of several millions of particles/cm3.
Characterization of these nanoparticles is generally highly complex and may complicate
riskassessment.ThepotentialhazardofthePGNPs,similartoMNMs,dependsonfactors
like size, surface, form, composition etc. and may be comparable to the anticipated and
provedhazardsforMNMs(SCENIHR2009).Therefore,whencarryingoutaworkplacerisk
assessment identification and characterization of PGNPs cannot be ignored (SER 2012,
EU/US2012).Anexampleisdieselexhaustparticulates(DEP),asalistedcarcinogen(SDU
2011).DEPisahighlycomplexmixturecontainingnanoͲ,fineͲandcoarseͲmodeparticles
aswellasavarietyofgaseouscomponentsoftoxicologicalrelevance(e.g.nitrogenoxides,
carbonmonoxide,aldehydes).ThedominantcarbonͲbasedchemicalcompositionofdiesel
sootNPsbearssimilaritiestothatofseveralcommerciallyimportantclassesofMNMs(e.g.,
carbonͲbased fullerenes, nanotubes), whereas their physical structure (i.e., agglomerates
ofsphericalprimaryparticles)bearssimilaritiestoothersthatalsohaveastrongtendency
toagglomerate(e.g.,titaniumdioxidesandothermetaloxides)(Hesterbergetal2010).
ThetypeoftheairborneprocessͲgeneratednanoparticles(PGNPs)ishighlyspecific
for the materials processed, the way of processing, machinery used, temperature etc.
Typicalsourcesfortheformationofnanoparticlesatworkplacesarecombustionprocesses
(Donaldsonetal2005),soldering,welding,useofelectricalequipmentandfracturingand
abrasion activities like sanding, milling and drilling. Scymczak et al (2007) demonstrated
that universalelectricalmotorsemitnanoparticles witha highcontentofcopper.During
the operation of a universal motor, brushes made of graphite slide over commutator
contactbarsmadeofcopper.Thismovementcausestheformationofparticlesnotonlyby
mechanicalabrasion,butalsobybrushsparks.Scymczaksuggeststhatdomesticappliances
andelectricpowertoolsusingpowercontrolbyphaseanglemodulationcanbeastrong
sourceofnanoparticleswithahighcontentofcopper.Plasmacutting,metalinertgasand
tungsten inert gas welding, metal grinding, aircraft maintenance, brazing, food
27
__________________________________________________________________________________
preservation (smoking), smelting and laser ablation were shown to emit nanoparticles’
numberconcentrationsrangingfrom2x104to4x107particles/cm3nearvariousprocesses
(Riediger et al. 2007; Pfefferkorn et al 2010). Evans et al (2007) reported spatially and
temporally varying nanoparticle number concentration within an automotive grey iron
foundryfromprocessemissionsinincoming makeͲupairandtheheatingwithdirectfire
natural gas burners, melting and pouring operations ranging from 1.9x104 to 3.5x106
particles/cm3. Evans et al (2010) reported elevated nanoparticles concentrations up to
1.15x106inacarbonnanofibers(CNFs)productionplant,butnotedthattheconcentrations
werenotduetoCNF,butreleasedduringthermaltreatmentofCNFs.Petersetal(2006)
reported a large variation in airborne NPs concentrations in a machining and assembly
facilityinthewinterandspring,probablygeneratedthroughevaporationandsubsequent
condensation of metalworking fluid components and demonstrated that these ultrafine
particlespersistinworkplaceairoverlongtimeperiods.Petersetal(2009)demonstrated
that airborne nanoparticles in a production facility producing nanoͲlithium titanate are
dominated by “incidental” sources (welding or grinding), and that the airborne
“engineered”productispredominatelycomposedofparticleslargerthanseveralhundred
nanometers.
Also laser applications may generate NPs. Barcikowski et al (2007) showed that
duringshortͲpulseandultrashortͲpulselaserablationreleasedNPsfromthematerial(laser
ablationisanapplicationofalaserforthecleaningandconservationofartworksofdifferͲ
entmaterialslikepaper,stone,metals,leather).Barcikowskietal(2007)notedthatfemtoͲ
secondlaserablationcausesthereleaseoffinerparticlesthannanosecondlaserablation,
whichmaybeduetohigherenergydensity.Intheirstudyonlasercleaningofpaper,they
showa dependence on the fibre-size of the paper as cleaningofshortͲfibrepapergeneratesa
higheramountofnanoparticlesthancleaninglongͲfibrepaper.Modernlaserprinterswere
showntoemitpeakNPemissionratesoftheprintersexceeding7.0x108sͲ1(sizebetween
11and79nm)andreachingconcentrationstomaximum2.6x105particles/cm3(Koivistoet
al2010).
Abrasion of surfaces coated with nanoͲenabled coatings may generate nanoparͲ
ticles as well, but it seems to be the use of electrical equipment that dominates the
generation of nanoparticles (Kopponen et al 2009; Göhler et al 2010; Wohlleben et al
2011). The studies show the generation of nanoparticles during the sanding process of
conventional and nanoͲenabled coatings. However, no significant difference could be
observed between coatings containing and not containing nanoparticle additives.
Kopponenetal(2009)notethatthehandͲheldsanderwasthemainsourceparticleswitha
diameter<50nm.Thefractionwithlargerparticlesisrathermadeupfrommatrixmaterial,
whichcontainsthenanoadditivesembeddedinthecoating(Göhleretal2010).Figure5
summarizessomeofthesefindings.
28
Background Concentrations and Process Generated Nanoparticles
___________________________________________________________________________________
Fiigure5
Indicationofconcentrationsofsome
eprocessgeneratednanop
particles
Process–geeneratedparticllesconcentratio
on(particles/cm
m3).Sources:seeeprevioustexxt.
Welding
800.000Ͳ 4.00
00.000
Bakery
640.000
Plasmacutting
>500.000
Soldering
000
400.0
Grindingmetal
150.000
Ind
dustrialactivitiess
M
Meltingsilicone
0.000
100
V
Vacuumcleaner
Offficeactivities
300.000
Laserprinter
260
0.000
Officework
10.000
0
200.000
400.000
600.00
00
80
00.000
1.000.000
AdditionallyttothePGNPssgenerated inprocessess,thereareaalsoconventtionalcompo
A
ounds
th
hat contain a fraction of
o particles at the nano
oͲsize that may
m give risee to emissio
ons of
nanoparticless at the workplace. Thiss thesis sho
ows that durring paint m
manufacturin
ng the
emissionofnanomaterialsfromconveentionalcom
mponentsmightbesignifficant(chaptter4).

Insum
m,thebackggroundconcentrationoffnaturaland
danthropogeenicnanoparrticles
iss variable an
nd in urban environments strongly impacted
i
byy traffic exhaaust (and exxhaust
gasses from industrial processes wh
hen not properly filtered). It may locally reach
h high
leevels.Inurbaanareaswithrelatively lowpollutionlevelsanaaveragebackkgroundof1
10,000
3
to
o 20,000 paarticles/cm is common
n. The conccentration of
o nanoparticles at indu
ustrial
w
workplacesge
eneratedbyheatingand
dcombustion
nprocesses,byelectricaalandhighͲe
energy
(laser) equipm
ment, as weell as due to the use of conventionaal powders w
with a fractiion of
nanoͲsized particulates,
may be co
p
onsiderable. It is likely that in many cases, when
nanomaterials or nanoͲeenabled prod
ducts are ussed, processͲgenerated nanoparticle
es will
dominatetheeairbornenaanoparticles’numberco
oncentration.Itisalsolikkelythatairborne
PGNPs may pollute
p
‘convventional’ workplaces where
w
no nan
nomaterials are handled
d. This
in
ndicates the importancee of taking nanoparticle
n
es into accou
unt when caarrying out a risk
assessmentin
naconventio
onalworkplaacewhereheatingorcombustionis atstakeorw
where
uipmentisused.Thisho
oldsaswellffortheuseo
ofconventio
onalpowderss.Itis
electricalequ
advisable for these sourcces in case of
o insufficien
nt knowledgge or uncertaainties to ap
pply a
precautionaryyapproachaaswell,similaartotheriskkmanagemeentapproach
hforMNMs.
29
__________________________________________________________________________________
1.6
Exposurelimitsfornanomaterials
F
rametoderiveanOELandaDNEL
Requirements regarding risk management of chemical substances in European
Member States are embedded in the legal frame, as defined by the Occupational
Safety and Health Framework Directive (OSHD 1989) and the Chemical Agents Directive
(CAD 1998). Both directives lay down the employers’ obligation to take the measures
necessary for the safety and health protection of the workers, including prevention of
occupationalrisks.TheCADdoesnotrefertonanomaterialsassuch,butaccordingtolegal
analysis,thegeneralobligationsapplyaswelltonanomaterials(EC2008).TheCAD(1998)
laysdownminimumrequirementsfortheprotectionofworkersfromriskstotheirsafety
andhealtharising,orlikelytoarise,fromtheeffectsofchemicalagentsthatarepresentat
theworkplaceorasaresultofanyworkactivityinvolvingchemicalagents.TheCAD(1998)
defines the employers’ obligations to assess risks arising from the presence of chemical
agents at the workplace and states that the employer shall obtain information from the
supplierorfromotherreadilyavailablesources.TheCADdefinesOccupationalExposure
Limits(OELs)asatooltoprotectworkersfromchemicalrisksandstatesthatOELscanbe
used as a tool for risk assessment. The OEL is defined as the limit of the timeͲweighted
averageoftheconcentrationofachemicalagentintheairwithinthebreathingzoneofa
worker in relation to a specified reference period, generally referring to an 8hrs timeͲ
weightedaveragedperiodoverafullworkingweekduringanentireworkinglife(ArboporͲ
taal,nd).DistinguishedareintheNetherlandshealthͲbasedOELsandriskͲbasedOELs,the
latterreferringtocarcinogenic,mutagenicandallergenicsubstancesforwhichathreshold
foranadverseeffectcannotbedefined.Forcarcinogenicsubstancestworisklevelshave
beenagreedintheNetherlands:a‘prohibitive’risklevelcorrespondingwithanadditional
cancer risk of >10Ͳ4/ substance/year and a ‘target’ risk level corresponding with an addiͲ
tionalcancerrisklevelof>10Ͳ6/substance/year.Forinhaledallergenicsubstancesa‘target
risklevel’hasbeenagreedcorrespondingwithanadditionalrisktobecomesensitizedof
1%(10Ͳ2/substance/year)(SERnd).TheriskͲbasedOELsarecurrentlyunderdebateinthe
EuropeanUnionasanoptionforaEuropeanapproach(ETUI2012).IntheNetherlandsthe
employers(c.q.the manufacturerorsupplier) have theobligationtoderivehealthͲbased
OELsforthesubstancestheymarket,whilefortheriskͲbasedsubstances,andafewother
substances (“without owner”) generated at the workplace the Dutch Ministry of Social
AffairsbearstheresponsibilitytoderiveOELs.
TheEUREACHlegislationdefinesDNELs(DerivedNoͲEffectLevel)andDMELs(deriͲ
ved minimumͲeffect level) (REACH 2006). REACH requires manufacturers to derive a
healthͲbasedDNEL forsubstancestheymarketinavolumeof>10tonnes/year/company
(ECHA 2010). The type of hazard data required depends on the market volume (ECHA
2008).REACHprescribestheuseofspecifiedassessmentfactorsforderivationoftheDNEL,
whichcontraststhederivationofOELs,whichleavesmorescopeforexpertjudgment(i.c.
by the European Scientific Committee on Occupational Exposure Limits, abbreviated:
SCOEL).IthasbeensuggestedthatthiswillleadtoDNELs,whicharegenerallylowerthan
OELs(SchenkenJohanson2011).HoweverinpracticethereareexamplesofOELsestabͲ
lishedatalowerlevelthantheregisteredDNELs(vanBroekhuizen2011a).IthasbeenarͲ
30
Exposure Limits for Nanomaterials
___________________________________________________________________________________
gued that it is preferable to harmonize the procedures for deriving OELs and DNELs to
avoid confusion (Kalberlah 2007, Schenk and Johanson 2011), but a standardized proceͲ
duretoderiveanOELfromaDNELisnot(yet)agreed.Forsubstanceswithoutathreshold
effectlevelREACHproposestouseaDMELthatshouldfollowariskͲbasedapproach(ECHA
2010). To date the methodology to derive a DMEL is under debate in Europe (Püringer
2011)andnoDMELsforsubstanceshavebeenderivedyet.
OELsandDNELsfornanomaterials
The REACH guidance extends to deriving DNELs for nanomaterials (ECHA 2012a). So far
howevertheregistrationofDNELsfornanomaterialsisexceptionalandtotheextentthat
nanoparticulatematerialsareregistereditisnotclearwhetheradequatenanotoxicological
data have been used. Illustrative is the registration in the REACH registration dossier in
2012 of carbon black and silica fume as materials for which a nanosize is likely (REACH
2012).Bothareknowntohaveprimaryparticlesofwhichasubstantialnumberislikelyto
beinthenanoͲrange(<100nm)(Kuhlbuschetal2010;Evoniknd).Theparticlesizeofthese
materials is not published in the REACH registration dossier. Both particulates have an
establishedregulatorylimitvaluesinsomecountries(e.g.GESTISnd137),butitisnotclear
whetherthesetakethenanoͲsizeintoaccount.
Illustrative is also that the frequently used nanomaterials like TiO2, ZnO, Ag and
Al2O3 have not been registered as nanoparticles (REACH 2012). The registered DNEL
(inhalationlongͲtermexposure,systemiceffects)forthesematerialsisthereforeassumed
toregardthecoarseform.ForCeO2ageneralworkerDNELͲinhalationforlongͲtermexpoͲ
surewithsystemiceffectsisregistered,withoutreferencetotheparticlesize.Itisnotclear
whether the published DNEL for CeO2 refers to the nano or the nonͲnano size, although
the identified use for this compound states “Used in industrial polishing Ͳ nano cerium
dioxide” and “Used as wood protection Ͳ nano cerium dioxide”, suggesting the DNEL to
refertothenanosizedparticulates(ECHA2011).ThenanoͲapplicationforCeO2ascatalyst
indieselfuel(Maetal2011)ishowevernotmentionedintheREACHregistrationdossier.
Table4summarizesthesefindings.
Table4 DNELs(inhalationlongͲtermexposuresystemiceffects)ofsome“parent”materials
fornanomaterials,aspublishedintheREACHregister,comparedwithOELs
Namesubstance
CASnr
DNEL(1)
3
OEL
Remarks
3
mg/m mg/m TiO2,Titaniumdioxide
13463Ͳ67Ͳ7
10
10
AgSilver
74440Ͳ22Ͳ4
0.1
Ͳ
ZnO,Zincoxide
1314Ͳ13Ͳ2
5
5
Al2O3,Aluminumoxide
1344Ͳ28Ͳ1
15.63
Ͳ
Graphite
7782Ͳ42Ͳ5
1.2
2
CB,CarbonBlack
1333Ͳ86Ͳ4
2
3.5
SiO2amorphous,smoke
SiO2,Silicafume
CeO2,Ceriumdioxide
60676Ͳ86Ͳ0
69012Ͳ64Ͳ2
1306Ͳ38Ͳ3
0.3
3
0.3
Ͳ
DNELforcoarseTiO2notfornanoͲTiO2.OELisACGIH
forcoarseTiO2
NotregisteredfornanoͲAg
NotregisteredfornanoͲZnO.OELisDutchOELfor
ZnOͲsmoke
DNELLocaleffects,notnano
DNELLocaleffects.OELisACGIHvalue(excl.fiber
formsofgraphite)
DNELforsystemicaswellaslocaleffects.OELis
ACGIHvalue
GermanOELfortherespirablefraction.
DNELonlyregisteredforlocaleffects.
REACHregistryexplicitlymentionsnanoͲapplications
(1)DNELͲinhalationforworkerswithlongͲtermexposuresystemiceffects
31
__________________________________________________________________________________
ForafewspecificnanomaterialstheindustryandresearchhaveadvisedanOELoraDNEL.
Thesearesummarizedintable5.Bayer(Pauluhn2009),Nanocyl(2009)andNIOSH(2010)
proposed OELs for multiwall carbon nanotubes (MWCNTs). DNELs were calculated in an
experimental study by Stone et al (2009) applying the DNEL methodology with the
prescribedassessmentfactorstoMWCNTs,fullerenes,AgandTiO2(seetable5).
Table5 OELsandDNELsasproposedbyindustryandbyresearchgroups
3
Substance
OEL
μg/
3
m DNEL
3
μg/m Particles/cm (5)
MWCNT(Baytubes)
8ͲhrTWA(6)
50
7.1x10 Ͳ3.2x10 MWCNT(10Ͳ20nm/5Ͳ15μm)(1)
Reference
6
7
Pauluhn,2009
4
5
Stoneetal2009
3
4
Stoneetal2009
2
4
Stoneetal2009
2
4
Stoneetal2009
ShortͲterminhalation(8)
201
4.1x10 Ͳ5.1x10 Chronicinhalation
33.5
7.1x10 Ͳ8.5x10 ShortͲterminhalation(8)
4
8.5x10 Ͳ1.0x10 Chronicinhalation
0.67
1.4x10 Ͳ1.7x10 MWCNT(Nanocyl)
8ͲhrTWA
2.5
Nanocyl2009
CNT(SWCNTandMWCNT)
8ͲhrTWA(7)
7
NIOSH2010
CNF(carbonnanofibers)
8ͲhrTWA
7
MWCNT(10Ͳ20nm/5Ͳ15μm)(2)
NIOSH2010
5
Stoneetal2009
3
Stoneetal2009
5
ShortͲterminhalation(8)
44.4
2.9x10 Chronicinhalation
0.27
1.8x10 ~800
2.7x10 NEDOͲ22009
DNELͲlungscenario1(3)
0,33
4000
Stoneetal2009
DNELͲlungscenario2(3)
0.098
1200
Stoneetal2009
DNELͲliver
0.67
7000
TiO2(21nm)
Chronicinhalation
17
8.3x10 TiO2(10Ͳ100nm)(REL)(4)
10hr/day,40hr/week
300
4.5x10 –4.5x10 Fullerenes
Fullerene
Ag(18Ͳ19nm)
TiO2P25(primarysize21nm)
TWA8h/d,5d/w
3
(1)BasedonaNOAECforpulmonaryeffectsof5mg/m (for
6hours)
(2) Based on a LOAEC for systemic immune effects: 0,3
3
mg/m (for6hours)
(3) Extrapolating the LOAEC to a NAEC using an
extrapolationfactorof3(scenario1)and10(scenario2)
(4)REL=RecommendedExposureLimit
Stoneetal2009
5
4
Stoneetal2009
7
NIOSH2011
7
1200 6.5x10 NEDOͲ12009
(5) Thenumberofparticles/cm3wascalculatedassuming
that the particles have a spherical form, and CNTs
haveacylindricalform.
(6) TWA=Timeweightedaverage
(7) 8hrͲTWA,40Ͳhour/week,50weeks/year,for45years
(8) ͳͷǦǡ

ThedifferencesinthevaluesforMWCNTsuggestthatdifferenttoxicologicalconceptsand
sample characteristics may lead to a different limit value. Pauluhn (2009) assumes that
assemblages of MWCNT lead to volumetric lung overload, which triggers a sustained
pulmonary inflammation. Stone et al (2009) suppose immune effects to be the critical
effectandderiveasignificantlylowerDNEL.Stoneetal(2009)emphasizethattheremight
besubstantialdifferencesinthepotentialofdifferentCNTstoinducetoxiceffectsoreven
tumors, depending on the form and properties of the carbon nanotubes. Stone et al.
(2009)suggestthatevaluationswillhavetobemadeonacaseͲbyͲcasebasis.NIOSH(2010)
basedtheirproposalforarecommendedexposurelimit(REL)regardingmultiwallcarbon
nanotubes on the limit of quantitation (LOQ) of NIOSH Method 5040, currently the
recommended analytical method for measuring airborne CNT. The LOQ for the NIOSH
method5040is7ʅg/m3.NIOSH(2010)statedthatanexcessriskofadverselungeffectsis
predictedbelowthislevelandthereforeadvisedtoreduceairborneconcentrationsofCNT
and CNF as low as possible below the REL. It is not clear how the manufacturer Nanocyl
deriveditsproposalforanOELfortheirMWCNTsbuttheirproposal(Nanocyl2009)isin
linewiththeNIOSHadvice.
32
___________________________________________________________________________________
NIOSH(2011)proposedanOELfornanoͲTiO2basedontoxicologicaldataandused
theUSthresholdlimitvalue(TLV)forcoarseTiO2(of1.5mg/m3)asreference.TheNIOSH
proposalishigherthantheDNELproposedbyStoneetal(2009),whichreflectsthestrict
useofspecifiedsafetyfactorsasprescribedintheDNELͲmethodology.ThehigherOELfor
TiO2asproposedbyShinoharaetal(NEDOͲ12009)mightbecausedbyahigherdensityof
theTiO2studiedbyShinoharaetal.2009).
A generic approach for the derivation of DNELs for manufactured nanomaterials
was proposed by Pauluhn (2010), based on the evidence that repeated rat inhalation
exposure studies suggest that the particle displacement volume is the most prominent
unifying denominator linking the pulmonary retained dose with toxicity (the overload
hypothesis). He calculates a volumeͲbased generic concentration of 0.54 μl PMresp/m3
(PMresp= respiratory particulate matter) to represent a defensible OEL. Related mass
concentrations can be calculated by multiplication of the volume concentration with the
agglomeratedensity:Cm=0.54μlPMresp/m3×ʌ,whereCmisthemassͲbasedconcentration
and ʌ is the PMͲagglomerate density. Calculating DNELs with this algorithm gives rise to
DNELs with a similar magnitude as the DNEL for (coarse) parent for materials. The
“PauluhnͲapproach”hasbeenscrutinized bythe RIVM(2012),anditwas concludedthat
the overload hypothesis cannot be seen as representative for the critical effect of
nanomaterials.Inchapter4ofthisthesistheapproachsuggestedbyPauluhn(2010)willbe
comparedwithothergenericapproaches.
OELsandDNELsfornanomaterialsandaprecautionaryapproach
SofarneitherwithintheDutchnorwithintheEuropeanlegalframeworksOELsorDNELs
for nanomaterials have been derived on the basis of nanotoxicological data. As shown
above,onlyforalimitednumberofnanomaterialsspecificOELsorDNELshavebeenproͲ
posed.
An important hurdle to the derivation of healthͲbased OELs and DNELs for
nanomaterialsistheinsufficiencyofhazard data.Additionallythereis theneed toadapt
themetricsusedforOELs(andDNELs)tothecharacteristicsofnanomaterials:metricssuch
asparticles’surfaceareaconcentration(cm2/m3)andnumberconcentration(number/m3)
maywellbeabettermetricforriskassessmentthanmass(Abbottetal2010,Ashbergeret
al2010,Ramachandranetal2012).Alsothecharacteristicsoftheairbornenanoparticles
shouldbeconsidered,whichmightbestronglyinfluencedbytheassembliesformed.Inthis
contextECHA(theEuropeanAgencyadministeringREACH)notesthattheparticles’toxicity
asͲproduced,asͲexposedorasͲinteractedmaydiffer(ECHA2012b).TherearealsoknowͲ
ledgegapsinparticletoxicologyandthestudyofparticleͲinducedcarcinogenesistodecide
whetherforcertainnanomaterialsahealthͲbasedorariskͲbasedOELshouldbeadvisable
orthatevenanotherapproachispreferable(Shvedovaetal2010).
Forriskassessmentofnanomaterials(includingthederivationofOELsandDNELs)
a caseͲbyͲcase approach is advocated, similar to chemical substances (ECHA 2012a). But
evenforthemostfrequentlyused(andstudied)nanomaterialslikenanoͲTiO2andcarbon
nanotubes(CNT)theavailabletoxicologicaldataarelimitedandtheadvisedrisklevelsmay
vary due to different methods and assumptions used to derive the OELs (Kuempel et al
2012) and possibly due to differences in characteristics of the nanomaterials studied as
well(seetable5).
33
__________________________________________________________________________________
Asexplainedinsection1.4insuchcasesanoptionistoinvoketheprecautionaryprinciple
andtoderiveprecautionͲbasedlimitvalues.
A problem with the derivation of precautionͲbased limit values is that the legal system
defines its frame for risk assessment to a healthͲbased or riskͲbased approach and does
not include a precautionͲbased approach for setting OELs. Also it might be argued that
precautionͲbasedlimitvaluescannotguaranteetoprotectthehealthofworkers.However,
itisclearthatalackofhazarddatadoesnotreleasetheemployerfromtheobligationto
provide a safe workplace. In view thereof, as will be further elaborated in chapter 2 the
precautionary approach to the use of nanomaterials may be operationalized by the
convertingtheREACHprinciplenodatanomarketintotheprinciplenodatanoexposure.
Thismightinprinciplebeguaranteedbyfullcontainmentoftheprocessinoperation,but
workplaceexperiencesuggeststhatevensuchsystemscannotguaranteethatsubstances
arenotreleased.Filling,cleaningandmaintenanceoperations,leakagesoraccidentsmay
releasenanoparticlesintheworkplace(Reijnders2012).Itmayalsobearguedthatwhen
noexplicitchoiceismadeforanexposurelimit,theimplicitchoiceismadetoregardthe
current exposure level as acceptable. Against this background the Dutch Social and EcoͲ
nomicCouncil(SER)concludedthatprecautionͲbasednanoreferencevalueswereneeded
toprovisionallyfillthisgapduetotheabsenceofOELsandDNELsandadvisedtheMinister
ofSocialAffairstoacceptthisapproach(SER2012).
Precautionarygenericapproachestostandardsetting
The approach based on nano reference values is one of the proposed precautionary geͲ
nericapproachestostandardsetting.Thefirstofthesegenericapproacheswasproposed
bytheBritishStandardsInstitute(BSI2007).BSI(2007)proposedagenerichazardͲbanding
concept for limit values based on the assumption that the hazard potential of the
nanoparticleisgreaterthanthehazardpotentialofalargeparticle.BSIappliedtheprinciͲ
pleof‘standardsettinginanalogy’andacknowledgedthatthisassumptionwouldnotbe
validinallcases.BSIstatedthatalthoughthelevelsrelatetoexistingOELsforbulkmateͲ
rials,theyareintendedaspragmaticguidancelevelsonlyandshouldnotbeassumedtobe
safeworkplaceexposurelimits.
IFA(InstitutfürArbeitsschutzderDeutschenGesetzlichenUnfallversicherung)(IFA
2009andupdatedin2012)furtherdevelopedthe precautionary,generichazardͲbanding
concept assuming that the particles’ surface triggers the potential effects and can be
characterized by the size and the density of the nanomaterials. IFA proposed to use the
particles’numberconcentrationrequiredtoattainamassconcentrationof0,1mg/m³for
particlesinthesizerangeupto100nm.Indoingso,IFAreferredtoanumberofexisting
andproposedexposurelimitsforparticles,whichIFAthoughttoberelevant,suchasthe
NIOSH proposal for nanoͲTiO2 (NIOSH 2011) and the German risk limits for respirable
biopersistent granular toner particles (BAUA 2010). To derive benchmark levels for
granularnanoparticleswithasphereͲlikeshape,andnormalizedatadiameterof100nm,
IFAcalculatedthenumberofparticles/cm3thatcorrespondtoamassconcentrationof0,1
mg/m3(seeChapter7,table2atpage158).Thesecalculationsleadtotworiskbandsfor
insoluble granular nanoparticles: one for nanomaterials with a density <6.000kg/m3 and
one with a density >6.000kg/m3. Consequently, for granular nanoparticles with a smaller
34
___________________________________________________________________________________
diameter the massͲbased benchmark level is stricter: for nanoparticles with a 50 nm
diameterafactor8,andwitha20nmdiameterafactor125.Forcarbonnanotubes(CNTs)
for which no manufacturer's declaration is available stating that the CNTs do not exhibit
asbestosͲlike properties, IFA proposed a provisional fibre concentration of 10,000
fibres/m³,basedupontheGermanexposureriskratioforasbestos(BAUA2008).Inviewof
theDutchlimitvalueforasbestos,whichwasrecentlyfurtherreduced,thebenchmarkfor
suchCNTsmightevenhavetobesetatalowerlevel(SER2011).IFAadvisedtousealowͲ
riskbandforsolublenanomaterialssimilartotheOELforthecoarse(ormolecular)form.
RIVM evaluated the usefulness of the BSI and IFA concepts (Dekker et al 2010) and
concluded that the benchmark levels suggested by IFA can be used as provisional and
pragmaticnanoreferencevalues(NRV)toreducetheworkers’exposuretonanomaterials.
Dekker et al. (2010) emphasized that the NRVs, as presented here, are not healthͲbased
andproposedtousetheNRVsintheNetherlands.
Hesterberg et al (2010) proposed to use diesel exhaust particulates (DEP) as a
genericmodeltosuggestlimitsfortoxiceffectsofnanoparticles.TheInternationalAgency
forResearchonCancer(IARC)classifieddieselengineexhaustascarcinogenictohumans
(Group1),basedonsufficientevidencethatexposureisassociatedwithanincreasedrisk
forlungcancer(BenbrahimͲTallaaetal2012).Hesterbergetal(2010)statethatDEP,asa
complexmixtureofultrafineandcoarseparticlesandavarietyofgaseouscomponentsof
toxicological relevance (e.g. nitrogen oxides, carbon monoxide, aldehydes), may bear
similarities to e.g. fullerenes, carbonͲbased nanotubes and to sphereͲshaped primary
particles,whereastheirphysicalstructure(i.e.,agglomeratesofsphericalprimaryparticles)
bearssimilaritiestoothersthatalsohaveastrongtendencytoagglomerate(e.g.,titanium
dioxidesandothermetaloxides).TypicalsizedistributionsforDEPwerefoundforprimary
particles in the range of 15Ͳ40nm, and for agglomerates in the range of 60Ͳ100nm
(Burtscher2005). Hesterbergetal(2010)suggestedaNOEL(noͲobservedeffectlevel)for
cardioͲvasculareffectsforDEPatanexposurelevelbetweenof100μg/m3PM2.5(3×104
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order of magnitude as the proposed levels for NRVs for biopersistent granular
nanomaterials.
Insum:itishighlyquestionablewhetherinthenearfuturesufficienthealthͲbased
OELsand/orDNELswillbecomeavailabletosupportemployerstofulfilltheirlegaldutyof
providing a safe workplace. PrecautionͲbased nano reference values (NRVs) may fill the
gapcreatedbytheabsenceofhealthͲbasedOELsand/orDNELs,butmustbeworkableand
acceptable.Thisisanimportanttopicinthefollowingchapters
35
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44
Chapter 2 Building Blocks for a Precautionary Approach to the Use
of Nanomaterials: Positions Taken by Trade Unions and Environmental NGOs in the European Nanotechnologies Debate Published in: Risk Analysis (2011), 31(10):1646‐1657 45
____________________________________________________________________________________________________________
46
Building Blocks for a Precautionary Approach to the Use of Nanomaterials
____________________________________________________________________________________________________________
Building Blocks for a Precautionary Approach to the Use
of Nanomaterials: Positions Taken by Trade Unions and
Environmental NGOs in the European
Nanotechnologies Debate
Pieter van Broekhuizen1∗ and Lucas Reijnders2
As partners in the European capacity-building project NanoCap, trade unions and environmental nongovernmental organizations (NGOs) have established positions on the development of nanotechnologies. Key in their positioning is their view that the use of nanomaterials
with currently unknown occupational and environmental hazards must have consequences
for the risk management and use of nanoproducts. They have made proposals for responsible
manufacturing and for applying the precautionary principle to the use of nanoproducts and
they urgently call for the acceptance and the operationalization of a precautionary approach
by the industry and governments. The trade unions and NGOs are calling for transparency
and openness regarding processes and products that contain nanomaterials and have proposed specific tools for nanomaterial use that put the precautionary principle into practice,
including the principles no data → no exposure and no data → no emission. The proposed
tools also include compulsory reporting of the type and content of nanoparticles applied in
products, a register of workers possibly exposed to nanoparticles, and the use of nano reference values as guides to assess workplace exposure to nanoparticles.
KEY WORDS: Engineered nanomaterials; environmental NGOs; nano reference values; nanotechnologies debate; occupational exposure limits; precautionary approach; public debate; trade unions
1. INTRODUCTION
properties, and applicability of such nanosized materials for professional and consumer products opens
new horizons.(1,2) Due to their small size nanoparticles (NPs) exhibit novel properties (different from
their bulk counterparts—larger particles with the
same chemical composition), such as high tensile
strength, low weight, high electrical and thermal conductivity, unique electronic properties, and high catalytic activity. New products that use these novel
properties, such as paints and coatings, sunscreens,
cosmetics, nanomedicines, self-cleaning glass, semiconductors, and food, are entering the market and
new technological opportunities are forecasted.(3)
The NP challenge includes dealing with potential environmental and occupational health risks.
Emerging nanotechnologies pose a challenge for
academic and industrial R&D to explore new scientific pathways and to develop materials and products
with new qualities based on properties of matter at
the nanoscale. The scientific focus is not always entirely new, but the technological focus, exploring the
1 IVAM
UvA Research and Consultancy on Sustainability, NL1001ZB Amsterdam, Netherlands.
2 University of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics, Amsterdam, Netherlands.
∗ Address correspondence to Pieter van Broekhuizen, IVAM
UvA Research and Consultancy on Sustainability, P.O. Box
18180, NL-1001ZB Amsterdam, Netherlands; tel: 31 20 525 6324;
fax: +31 20 525 5851; pvbroekhuizen@ivam.uva.nl.
47
____________________________________________________________________________________________________________
>10 tons/year. To date there are many nanomaterials
that are marketed in lower volumes. For nanotechnological R&D, where lack of empirical exposure data
and toxicological uncertainties prevail, the European
Commission therefore advises the use of the precautionary principle,(25) as explicitly stated in its Code
of Conduct: “N&N research activities should be conducted in accordance with the precautionary principle, anticipating potential environmental, health and
safety impacts of N&N outcomes and taking due
precautions, proportional to the level of protection,
while encouraging progress for the benefit of society
and the environment.”(26)
How precaution in nanotechnologies should be
brought into practice for manufacturing and use of
nanoproducts is the subject of a public debate. Some
environmental nongovernmental organizations
(NGOs) are calling for a strong precautionary approach to the development of nanotechnologies and
recommend a product ban for all applications associated with releases leading to human or environmental exposure until evidence shows that they are safe
for both human health and the environment.(27−32)
The U.K. Soil Association(33) banned the use of manmade NPs from all their certified organic health and
beauty products, as well as food and textiles. In theory the European industry endorses a precautionary
approach, but the European industry has also stated
that regulation is only called for if scientific evidence
demonstrates that nanomaterials are harmful,(34)
apparently opting for voluntary measures as long
as scientific uncertainty exists.(35) This ambivalence
may be characterized as a conditional precautionary
approach. Regulatory bodies are of the opinion that
current legislation covers in principle the potential
health, safety, and environmental risks in relation
to nanomaterials, and state that only adaptation and
improvement of implementation is necessary.(36,37)
An example of the latter is the revision to cosmetics
regulation agreed by the European Parliament in
2009, obliging notification on the product label of
the NPs contained in the cosmetic product.(38)
Governing bodies often aim at involving the relevant stakeholders in the discussion on nanotechnologies. Various governmental initiatives were carried
out or are underway to organize public nanoengagement activities.(39−47) However, this may be not uncontroversial as Rip(48) stated: “they tend to do so
with a narrow freedom of action leading to predetermined boundaries in the government-orchestrated
debate.” The role of ethics in the debate is often
emphasized, but critical remarks about the role of
Recent toxicity data about commonly used NPs show
hazardous properties for aquatic organisms.(4) Indications for human health hazards have been reported
by many research groups showing oxidative stress, fibrosis, cardiovascular effects, cytotoxicity, and possibly carcinogenicity as effects of NP exposure.(5−11)
The manufacturing, trade, and use of nanoproducts may lead to worker exposure and environmental
emissions of NPs while the extent and the potential
effects are still uncertain.(6,7,12−14) This means that
industrial employers and employees face the problem of dealing with uncertainties in developing safe
products and in designing company-specific measures
to prevent exposure and environmental emissions.
To cope with these uncertainties several initiatives to
guide industry to a safe use of NPs have been published, including several Codes of Conduct.(7,15−20)
Some industries have liaised with NGOs to develop a
framework for the responsible development and lifecycle management of engineered nanomaterials.(21)
Most of these guidance documents are formulated against the background of chemicals legislation(22) and the Chemical Agents Directive,(23) which
use the occupational hygiene strategy as a leading
principle. This is the hierarchical risk management
strategy, laid down in the CAD 1998, which ensures
that the risk from a hazardous substance to the safety
and health of workers at work is eliminated or reduced to a minimum. The strategy prefers substitution of (potentially) hazardous substances. In the
case that this is not possible, emission of the substance must be minimized by designing appropriate work processes, engineering control, and the use
of adequate equipment and materials. Subsequently,
if this is not possible adequate ventilation and appropriate organizational measures may be applied.
Finally, if these mitigating measures fail, personal
protective equipment may be used to prevent exposure. However, in practice companies often choose
the simple way out by selecting the final option in
the risk management hierarchy: prescribing the use
of personal protective equipment.
Although “Registration, Evaluation, Authorisation and Restriction of Chemicals” (REACH) does
embody the precautionary principle, to date it does
not deal explicitly with the use of nanomaterials.
Structured initiatives are underway to close some
of the identified gaps, for example, concerning the
characterization of NPs,(24) but others, like the obligation to provide a chemical safety report (CSR)
for hazardous substances, are only obligatory for
substances brought at the market in a volume of
48
____________________________________________________________________________________________________________
ethics are also made. Sally Randles(49) notes skeptically: “In the face of the ‘ethics deficit’ that produced the GMO debacle and its subsequent moratoria, this time things need to be done differently.
A spoonful of ethics will assist in this explicit pathclearing exercise by assuaging opposition and making nanotechnologies more ‘palatable’ to various
publics, thus enabling market acceptance. Small hurdles, like working with possibly very toxic substances
will have to be cleared by the formulation of good
practices for safe work and production and good
intentions to take care for man and environment
should be agreed by all stakeholders in the field.”
She emphasizes the importance of taking a proactive,
responsible, and transparent line by industrial and
governmental stakeholders concerning occupational
and environmental health and safety issues, to seriously address ethical issues in the debate to prevent a
strong opposition from civil society toward nanotechnological developments.
Participation of civil society in the public debate
on nanotechnologies is taking place against a background of public perception of risks and benefits and
is also influencing the latter at various levels. Trade
unions, environmental NGOs, and consumer organizations (together called civil society organizations,
CSOs) have a voice in the public debate, as representatives of many millions of citizens (professional
workers and consumers), and as protectors of the
general environment. Against this background, the
No
European project NanoCap organized a structured
capacity-building project for European trade unions
and environmental NGOs on nanotechnologies from
2006 to 2009.(50) The aim was to provide the CSOs
with the tools to take part in the national and European debate on nanotechnologies.
This article reflects on the issues brought forward
by the CSOs in the Nanocap project and the building blocks (principles and tools) they recommend using to make the precautionary principle operational
in the development of nanotechnologies. The CSOs’
recommendations are described as a precautionary
approach.
2. THE NANOCAP PROJECT
NanoCap was set up as a consortium of five European environmental NGOs, five trade unions, five
universities, and was coordinated by IVAM UvA
BV, the Dutch research and consultancy group dealing with sustainable development, occupational, and
environmental chemical risks (see Table I).
NanoCap worked for three years on the structured enhancement of stakeholder capacity to understand and critically assess nanotechnologies. The aim
was to assist trade unions and environmental NGOs
to develop a position on nanotechnologies and take
part in the public debate.
The trade union groups involved in the project
had already a long-standing cooperation in the field
Code
Participant Organization
Country
1
2
3
4
5
6
IVAM
SNM
LA
BEF
EEB
MIO
7
8
9
10
11
12
FNV
AMIC
ETUI
KOOP
PPM
UAAR
13
TUD
14
KUL
15
16
UES
ECDO
IVAM UvA BV
Stichting Natuur en Milieu
Legambiente onlus
Baltic Environmental Forum
European Environmental Bureau
Mediterranean Information Office for Environment,
Culture and Sustainable Development
Federatie Nederlandse Vakbeweging
AMICUS the Union
European Trade Union Institute
Kooperationsstelle Hamburg
ppm Forschung + Beratung Arbeit Gesuntheit Umwelt
University of Aarhus, Interdisciplinary Nanoscience
Centre (iNano)
Technical University Darmstadt, Institut für
Philosophie
Catholic University Leuven, Department of Public
Health
University of Essex, Biological Sciences
University of Amsterdam, Expertise Centre for
Sustainable Development
49
Netherlands
Netherlands
Italy
Lithuania
EU
Greece
Netherlands
Ireland
EU
Germany
Austria
Denmark
Germany
Belgium
United Kingdom
Netherlands
Table I. Participants in NanoCap
____________________________________________________________________________________________________________
Table II. NanoCap Working Conferences
of chemical risk policy. The European Trade Union
Institute (ETUI) is the technical bureau of the European Trade Union Confederation (ETUC) that represents the interests of trade unionists at the European level. ETUC currently comprises 82 member
organizations, from a total of 36 European countries
and 12 European industry federations, representing
more than 60 million workers. Amicus-Unite is the
largest trade union in Britain and Ireland with almost
2 million members. The FNV is the largest Dutch
trade union organization, with 19 national member
trade unions and 1.4 million members. The German
and Austrian NanoCap partners acted as intermediaries to the German and Austrian trade unions, and
were selected in consultation with these unions.
The European Environmental Bureau (EEB) as
umbrella organization represents 143 member organizations in 31 countries with a membership base
of more than 15 million. The Greek MIO federation represents 115 NGO members in 26 countries
around the Mediterranean while the Lithuanian BEF
represents NGOs from Latvia, Estonia, Lithuania,
and Germany. Legambiente (League for the Environment) is the largest environmental organization in Italy, with 20 regional branches and more
than 115,000 members. Finally, Natuur en Milieu, the
Netherlands Society for Nature and Environment, is
an independent environmental foundation without
members.
The universities involved took responsibility for
the scientific input. They were invited to participate
in the NanoCap project based on their expertise relevant to the nanotechnology debate, covering the
fields of technology, physics, chemistry, environmental science, occupational health, and ethics.
The agreement at the start of the NanoCap
project was that there was no obligation to end the
project with a single common position representing
all of the NGOs and trade unions involved. Each
partner was free to leave the project with its own vision and position on nanotechnologies.
The project focused strongly on engineered
nanomaterials and products, which contain engineered nanomaterials. The areas covered were technical issues, environmental and occupational health
risks, ethical issues, and an assessment of the claimed
benefits. Topics such as nanotechnological applications for medicine, nanoelectronic applications, and
military nanotechnologies were largely left outside
the scope of the activities organized.
The capacity-building process was initiated by
the CSOs drawing up Action Plans, identifying relevant nanotechnologies’ stakeholders their inter-
Working
Conference
1
2
3
4
5
Topics
Basics of nanotechnology
Technical and chemical-physical
nanotechnological issues
OHS & environmental Issues
related to nanoparticles
Ethical issues nanotechnologies
Critical assessment of benefits of
nanotechnologies
Organizer
ECDO
UAAR
UES & KUL
TUD
IVAM & TUD
ests and strategies in nanotechnologies development,
and developing national and European strategies to
involve them in the NanoCap activities. At eight
project team meetings, several separate trade union
and NGO meetings, and five subsequent one-andhalf-day working conferences (see Table II) the
strategies, nanotechnological issues, scientific certainties and uncertainties, the operationalization of
the precautionary principle, and priorities for the
positioning in the debate on nanotechnologies were
discussed.
The universities, with contributions of external
experts, organized the working conferences, all with
introductions to the topics followed by extensive discussions. The program for these different working
conferences was largely determined by the preceding
deliberations in the project team. All project partners
and their invitees attended the working conferences.
The Aarhus iNano Institute introduced the elementary and applied scientific basis of nanotechnologies; the Catholic University, Leuven, highlighted
the toxicological and occupational health aspects of
NPs; the University of Essex, the environmental and
chemical issues and metrics; the University of Amsterdam outlined the sustainability issues and the
precautionary principle; the Technical University of
Darmstadt (TUD) elaborated on the nano-ethical
issues and finally IVAM and TUD together organized the working conference assessing the claimed
benefits of nanotechnologies in relation to economical interests. Comprehensive factsheets including an
ethics portfolio were put together.(50) The NanoCap
team visited several companies involved in the production and use of nanomaterials and discussed with
the management the safe design, production, and use
of nanomaterials and nanoproducts. Subsequently,
both the trade unions and the environmental NGO
partners had separate deliberative meetings to develop their positions on nanotechnologies which
50
____________________________________________________________________________________________________________
were then discussed within their own national and
European organizations and finally agreed.
The project finalized with the organization of
the European Conference “Working and Living with
Nanotechnologies” in collaboration with the European Parliament body STOA (Science and Technology Options Assessment). Here CSOs publicly
presented and discussed their positions in the nanotechnologies debate.
It is estimated that approximately 1,500 persons
were directly involved in one or more NanoCap
activities, excluding those who were informed via
national dissemination activities of the partners.
During the project the NanoCap website had more
than 180,000 visitors.
keting, and use of nanomaterials at all stages of their
life cycle. They also call on the Commission to amend
the REACH regulation so as to give better and wider
coverage to all potentially manufacturable nanomaterials, especially with respect to the REACH registration requirements concerning market volumes
and CSRs. They want a CSR to be required for all
substances registered under the REACH regulation
for which a nanometer scale use has been identified. They take the precautionary principle as starting point and propose concrete measures to realize
transparent risk information for the workplace, not
only when working with substances known to be hazardous, but also on how to act when the hazards
of used substances are still unknown. Transparency
and openness on nanoproduct composition are key
elements in the ETUC position. In this respect the
ETUC states that industrial voluntary initiatives and
responsible codes of conduct may only serve a useful purpose pending implementation of the necessary
changes to the current legislative framework if there
is an independent and transparent system for assessing compliance and if sanctions are foreseen in the
case of noncompliance.
The environmental NGOs also emphasize the
need to operationalize the precautionary principle to
assure a sustainable development of nanotechnologies. Their position in the nanotechnologies debate
is strongly influenced by their experiences regarding
the GMO debate (genetically modified organisms),
where the precautionary principle was ignored despite the many scientific uncertainties. A key element
for the NGOs is their call for a premarket registration and a regulatory framework that anticipates the
safe management of future applications in advance
of their availability on the market. They note disagreement over the adequacy of existing legislation
to address the potential impacts of nanomaterials,
and stress that the European Commission’s regulatory assessment conclusions do not provide a solution to closing the regulatory gaps. The framework
should require registration of public and private research, and test-based assessment and approval of
near-market uses of nanomaterials. This information
should then be put into a publicly available inventory, as part of a coherent and comprehensive policy framework on nanotechnologies. They favor consultation on (nano)technological innovation, which
should include a systematic consultation of public
opinion about the needs for some innovations, as it
should not be assumed that they will all deliver social
advantages large enough to justify increased risk.
3. RESULTS OF THE NANOCAP PROJECT
The trade union groups, led by the ETUI,
reached an agreed position, endorsed in 2008 by the
ETUC and published as Resolution on Nanotechnologies and Nanomaterials.(51) The Dutch trade
union FNV(52) and the Irish/British trade union
Amicus/Unite(53) published derivative position statements that played a role in their national debates on
nanotechnologies.
The EEB published the collective environmental position for the environmental NGOs in 2009,(54)
with national derivatives appearing in Italy,(55)
Lithuania,(56) and the Mediterranean.(57) The Dutch
Natuur en Milieu presented its position directly to
the Dutch parliament.(58)
The ETUC notes that there are significant uncertainties regarding both the benefits of nanotechnologies to our society and the harmful effects of manufactured nanomaterials on human health and the
environment. The development of these emerging
technologies and the products from them also pose
huge challenges to society in terms of regulatory and
ethical frameworks. The ETUC considers that if the
past mistakes with putatively “miracle” technologies
and materials are not to be repeated, preventive action must be taken where uncertainty prevails. This
means the precautionary principle must be applied.
In their resolution the ETUC strongly focuses on
the legislative aspects of nanotechnologies, in particular in relation to the chemicals legislation REACH
and the Chemical Agents Directive.(17) They ask for
full compliance with REACH’s “no data, no market” principle, especially calling to refuse to register
chemicals for which manufacturers fail to supply the
data required to ensure the safe manufacture, mar-
51
____________________________________________________________________________________________________________
CSOs consider risk communication to be important. They stress that communication should not only
concern known hazards and risks, but should also
consider what is still unknown. In the case of possible human exposure to NPs and emission into the environment risk mitigating measures should be based
on a worst-case approach. Otherwise, the precautionary principle will remain meaningless. On that
point the CSOs achieved agreement on some practical tools to realize an operational and comprehensive
precautionary approach for working with nanomaterials. These are summarized in the following seven
building blocks:
(4)
(1) No data → no exposure and no data → no
emission
In spite of the REACH principle no data →
no market, practice shows that many nanomaterials characterized by incomplete data regarding risk are used in products that are currently marketed. The precautionary principle
starts from the basic assumption that these
nanomaterials can be hazardous substances.
Consequently, the CSOs state that all emissions and exposure to NPs over the full product life cycle should be prevented.
(2) Reporting of the content and type of NPs in
products.
Communication in the production chain
should be strongly improved. Manufacturers
and suppliers are called upon to report the
content and type of NPs in their products to
an independent body that will establish an inventory of nanomaterial-containing products
on the market. Manufacturers are also called
upon to report the content and type of NPs in
their products to the next user in the production chain.
(3) Registration of workers possibly exposed to
nanomaterials.
As part of the risk management system, and
for retrospective workplace analysis, the employer is called to keep records of the workers handling nanomaterials including: type,
handling, frequency, duration, known hazards, and any exposure-mitigating measures
in place. The following distinctions apply:
For nanofibres3 and CMRS nanomaterials
(carcinogenic, mutagenic, reprotoxic, or sen3
(5)
(6)
(7)
Nanofibres are especially the single-wall and multiwall carbon
nanotubes (SWNT and MWNT).
52
sitizing), the preferred format is the one used
in the existing obligation for registration of
working with carcinogenic substances.(59)
For other nonsoluble nanomaterials the preferred format is the one used in the existing
obligation for registration of working with reprotoxic substances.(60)
Transparent communication about known
and unknown risks.
Manufacturers and suppliers are called upon
to use the Safety Data Sheets to inform the
product user about identified risks of nanomaterials and to inform the user about existing uncertainties in knowledge that may
adversely influence the performance of a
reliable risk assessment. Manufacturers are
called upon to provide a CSR as defined in
the REACH directive,(22) including nanomaterials marketed in relatively low volumes, >1
ton/year/company.
Derivation of workplace exposure limits.
Employers and governmental agencies are
called upon to derive Health-Based Recommended Occupational Exposure Limits
(HBR-OELs) for NPs for which enough toxicological data are available.
If gaps in knowledge on toxicological properties exist, the derivation of provisional nano
reference values (NRVs) is an option; NRVs
are guidance values that take the precautionary principle into account by using the worstcase approach to establish provisional exposure limits for nanomaterials.
Development of an early warning system.
To support occupational health monitoring,
a system to identify early signals of adverse
health effects should be developed to relate
possible work-related illnesses to the exposure to specific NPs.
A comparable system should be developed
for environmental monitoring to relate identified environmental effects to the emission of
specific NPs.
Premarketing approval for all applications
of nanotechnologies and nanomaterials as a
central element of the policy and regulatory
framework.
CSOs emphasize that products should not
be marketed if they introduce new, or uncertain, risks to health or the environment, while their claimed benefits cannot be
substantiated.
____________________________________________________________________________________________________________
4. DISCUSSION
from the market. Given this situation, and the fact
that CSOs don’t want to enforce a total halt to industrial production and the conviction of the CSOs that
provisional (precautionary) measures must be taken
for as long as the gaps in knowledge remain unclosed,
the CSOs subscribe to the no data→ no exposure/
emission principle. This approach creates room for
industry to continue nanotechnological research and
development and even market nanoproducts on the
condition that they can prove the prevention of any
exposure to, or environmental emissions of, NPs. To
be effective, the no data → no exposure and no data
→ no market principles must be taken seriously by
industry.
The CSOs’ preference for this approach, which
has also been called a “too soon” scenario, implies
the acceptance that new evidence might show later
on that precautionary measures selected originally
were too strict and that preventive measures may be
weakened. It could also mean possible delays in marketing of specific products, due to the need to wait for
evidence of safe manufacturing and use. A “too late”
scenario, however, with society waiting for proof of
risk, while in the meantime workers, citizens, and the
environment are possibly put at risk is not acceptable
for the CSOs. The experience with asbestos is a deterrent example of the latter scenario, and this point
was raised in the NanoCap project. The REACH directive embodies a precautionary approach for hazardous substances that tries to avoid the “too late”
scenario by demanding premarketing hazard assessment. Therefore, an adaption that makes REACH
suitable for properly dealing with nanomaterials is
highly urgent.
To date several companies have adopted a precautionary approach and are delaying further development of their nanoproducts until they can fully assess the environmental or occupational health risks
of their products (Huisman, personal communication; Streekstra, personal communication). In doing
so, they risk their frontrunner positions in innovation, but they may gain the trust of society and avoid
possible nasty effects in future.
Some of the CSOs’ positions regarding precaution, notification, and transparency have been
recognized by the European Parliament.(65) The
European Parliament explicitly asked for a thorough
implementation of the no data → no market principle for nanomaterials to which workers, consumers,
and/or the environment may be exposed. The European Parliament has also called for specific amendments to be made in REACH, especially with regards
4.1. Precaution, Transparency, and Notification
According to the CSOs, precaution is a key element in nanotechnology policy development and
although the application of the precautionary principle is acceptable for many industrial stakeholders, as reflected by the publication of codes of
conduct, there is no agreement on how to put a precautionary approach into practice. A precautionary
approach, triggered and motivated by uncertainties
or ambiguity about nanotechnological hazard and
risk issues, generally competes with economical interests. Industrial interests in the development of
nanotechnology are expected to grow to a trilliondollar market.(61−63) Many industries use communication strategies that exploit the ambiguities of
nanotechnology to translate the technologies into a
moneymaking industry.(64) For instance, economical
interests led to the industries’ confidentiality policy and consequently restrict communication on the
nanomaterials used in products and their risks. Lack
of transparency and, as emerged in the NanoCap
project, confidential behavior make the CSOs suspicious.
A major element in the CSO position is the notion that public acceptance of the new technology
strongly depends on the transparency created by industrial and governmental stakeholders on currently
confidential issues regarding product composition
and associated risks. Therefore, the CSOs are asking governments to undertake legal steps to enforce
binding obligations for precaution, transparency, and
open communication. Their calls to oblige manufacturers to carry out a premarket nanoproduct
risk assessment, to report the composition of their
nanoproducts, to register exposed nanoworkers, and
develop nano references values are examples of their
approach to translate the precautionary principle
into practical measures.
The same holds for the CSO proposal for the
principles no data → no exposure and no data → no
emission. The starting point is the REACH principle no data → no market, but it cannot be denied
that numerous nanomaterials are already on the market, some of which had appeared long before these
materials were explicitly identified as nanomaterials
and before it was recognized that these materials may
have new and as yet uncertain (toxicological) properties. The actual situation with chemicals in Europe
suggests to the CSOs that a huge number of chemical substances with little or no data are not banned
53
____________________________________________________________________________________________________________
to the registration of nanomaterials, a CSR for all
registered nanomaterials, irrespective of their hazard
identification, and for a notification requirement for
all nanomaterials that are placed on the market, irrespective of their volume and concentration thresholds.
At the national level France aims at the compulsory notification to the administrative authorities,
prior to fabrication, importation, or distribution of
any nanomaterial, indicating the quantities handled
and the intended uses.(66)
In the Netherlands, developments in the Dutch
Social Economic Council (SER) have shown that it
is feasible to reach agreement between trade unions
and employers’ organizations on most of the building blocks for a precautionary approach.(67) Trade
unions and employers’ organizations have agreed on
the first six building blocks, even for the commercially highly sensitive point of notification (reporting)
of the nanomaterials used in products. However, the
last building block proposed by CSOs, premarketing approval of nanoproducts, has not been agreed.
Following the SER advice, the Dutch Parliament
has endorsed notification of the NP content of products,(68) and the derivation of provisional NRVs.(69)
The Parliament asked the Dutch government to seriously consider a binding notification and to establish NRVs for nanomaterials. However, in contrast
to the French approach, the Dutch have decided not
to launch a national initiative for binding notification, but to shift this initiative to European political
channels.
proaches. Another solution is the provisional use of
NRVs.
One possible precautionary approach has been
suggested by NIOSH for nano-TiO2 .(70) Based on the
increased reactivity of nano-TiO2 linked to the increase in surface area, NIOSH proposes a 15-fold
reduction for a nano-TiO2 limit value compared to
the existing OEL for large-particle TiO2 (1.5 →
0.1 mg/m3 ). This approach does not take into account
possible new specific effects that are observed for
some substances at the nanoscale.(71)
A more generic approach was proposed by the
British Standards Institute.(72) It follows the principle of “standard setting in analogy” and proposes
a risk-ranking system (see Table III) for the establishment of “guidance values,” which are called here
NRVs.
The BSI approach presupposes the derivation of
substance-specific NRVs, but this is only possible for
a limited number of NPs because for only a few has
an OEL has been established for its coarse form.
For these particles with no OEL for the coarse form,
BSI suggests that an alternative would be to develop
a benchmark based on particle number concentration. BSI suggests that 20,000 particles/mL above the
ambient environmental particle concentration is an
appropriate benchmark. This approach would be
useable as a generic benchmark and solves many
problems concerning the lack of data, but it ignores
any substance-specific toxicity.
One may note that the use of safety factors by
BSI is not substantiated. Peculiarly, very toxic CMRS
NPs get a lower safety factor than insoluble NPs. Furthermore, some confusion might arise about the apparently contradictory ranking system that includes a
separate group for soluble NPs while engineered NPs
are generally defined as insoluble materials. Nevertheless, the solubility characteristics of NPs are of
interest because the solubility of NPs may increase
significantly as size decreases,(73) which may have a
direct influence on the bioavailability and thus influence the toxicokinetic behavior of the substance.
Comments on the BSI methodology have also
been made by the German Institut für Arbeitsschutz
der Deutschen Gesetzlichen Unfallversicherung, the
IFA,(74) which introduces particle size and density of nanomaterials as important parameters to
determine benchmark levels (see Table IV) with
the metric particles per cubic meter. This generic
approach was adopted in the Netherlands for its
NRVs as an acceptable precautionary exposure level
for ENPs as long as HBR-OELs or DNELs are
4.2. Nano Reference Values
The call for the establishment of NRVs is related
to the use of occupational exposure limits (OELs) for
occupational risk assessment. It is the common practice in Europe to use health-based recommended occupational exposure limits (HBR-OEL) for this purpose, based on sound empirical data about hazards.
In REACH the derivation of DNELs (derived noeffect levels) is foreseen, to function as a basis for
the establishment of OELs. However, when sound
empirical data are lacking, which is still the case for
most commercial nanomaterials, an HBR-OEL cannot be established, leaving to the employer the task
to derive a provisional exposure limit for workplace
chemicals. For this the employer may use an expert
guess, a worst-case approach, a read-across method,
a SAR (structure activity relationship), or other ap-
54
____________________________________________________________________________________________________________
Table III. BSI, Nanoparticle Risk Ranking, and Proposed Guidance Values
Cat
i
ii
iii
iv
aA
Description
Guidance Value
Remarks
Fibrous materials; a high aspect ratio
insoluble nanomateriala
Any nanomaterial already classified in its
coarse particle form as carcinogenic,
mutagenic, reproductive toxin, or as
sensitizing (CMRS)
Insoluble or poorly soluble nanomaterials,
and not in the category of fibrous or
CMRS particles
0.01 fibers/mL
Analogous to asbestos fibers.
0.1 × existing OEL for molecular
form or larger particles
Soluble nanomaterials not in the fibrous or
CMRS category
0.5 × OEL
The potentially increased rate of dissolving of
these materials in nanoparticle form could
lead to increased bioavailability. Therefore a
safety factor of 0.1 is introduced.
In analogy with NIOSH a safety factor of 0.066
(= 15 × lower) is advised. An alternative
benchmark level is suggested as: 20,000
particles/mL above the ambient
environmental particle concentration.
A benchmark of 0.5 × OEL is proposed.
0.066 × existing OEL for molecular
form or larger particles
fiber is defined as a particle with an aspect ratio >3:1 and a length more than 5,000 nm.
Table IV. IFA Proposed Benchmark Levels
Description
1
2
3
4
CNT with a high aspect ratio (>3:1),
longer than 5,000 nm, insoluble
nanomaterial
Metals and metal oxides and other
biopersistent granular nanomaterial in
the range of 1 and 100 nm
(Metals and metal oxides and other)a
biopersistent granular nanomaterial in
the range of 1 and 100 nm
Density
0.01 fibers/cm3
10,000 fibers/m3
>6.000 kg/m3
20,000 particles/cm3
<6.000 kg/m3
Ultrafine liquid particles
a Text
Benchmark Level
(8-hr TWA)
Applicable OEL
Type
• CNT, for example asbestos-like SWCNT
or MWCNT without specific toxicity
information of the manufacturer
• Ag, Au, CeO2 , CoO, Fe, Fex Oy , La, Pb,
Sb2 O5 , SnO2 ,
• Al2 O3 , SiO2 , TiN, TiO2 , ZnO, nanoclay
• Carbon Black, C60 , dendrimers,
polystyrene
• CNT with explicitly excluded asbestos-like
effects
• e.g., fats, hydrocarbons, siloxanes
between parentheses inserted by the author for clarity of the description.
not available.(75) They refer to the background corrected ENP-concentration in the workplace atmosphere and are defined as a warning level to trigger
a thorough assessment of NPs at the workplace when
this level is exceeded. Then the source of the NPs’
emission(s) should be thoroughly identified and possibilities to reduce the emission of NPs must be assessed. The NRVs are quantified as an 8-hour TWA
exposure concentration (time weighted average exposure over the 8-hour working day).
in companies and in the European countries are
key players in the European nanodebate, influencing the opinion of the general public. According to
the NanoCap project design CSOs were free to develop their own, independent position in the nanodebate while deliberating with NanoCap partners
and in discussions with external stakeholders, such
as industry, consumer organizations, and policymakers. The independently developed positions from the
trade unions and the environmental NGOs show a
large similarity in their approach of nanotechnologies.
An important point is their demand for more
openness and transparency of the industry on manufactured nanoproducts and their possible risks.
Concerning nano legislative issues the CSOs identified that existing directives and regulations are
not addressing nanotechnologies adequately and ask
5. CONCLUSION
This article reflects on the deliberative approach
used in the NanoCap project, which enabled the
structured enhancement of the capacities of European CSOs to understand and critically assess nanotechnologies. The CSOs with their many members
55
____________________________________________________________________________________________________________
therefore for an updating of the current legislative
framework.
The precautionary approach operationalizing
the precautionary principle regarding the professional use of nanomaterials as proposed by the European CSOs can be summarized in seven building
blocks:
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J, Lebret E, Cassee FR, Wardekker JA, Ayres JG, Borm
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of Hazardous Materials. 2008; 152(1):440–445, available at
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15. VCI. Guidance for the passing on of information along the
supply chain in the handling of nanomaterials via safety data
sheets, Verband der Chemischen Industrie e.V. 6 March 2008.
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the workplace. Bundersanstalt für Arbeitsschutz und Arbeitsmedicin (Verband der Chemischen Industrie e.V. 2007.
http://www.baua.de/en/Topics-from-A-to-Z/HazardousSubstances/Nanotechnology/pdf/guidance.pdf;jsessionid=D
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(1) No data → no exposure and no data → no
emission.
(2) Reporting of the content and type of nanomaterials in products (traceability)
(3) Registration of workers possibly exposed to
nanomaterials
(4) Transparent communication about known
and unknown risks
(5) Derivation of workplace exposure limits
(6) Development of an early warning system
(7) Premarketing approval for all applications
and nanotechnologies and nanomaterials as a
central element of the policy and regulatory
framework
These building blocks may help in the development of governmental policy and may stimulate precautionary initiatives in industry. This may as well
help those industries still waiting with further development and marketing of nanoproducts for the
“outcome” of the nanodebate to take this hurdle. If
building blocks find enough support to become real
tools in a precautionary approach to nanotechnologies they may need further elaboration, as outlined
here for the case of NRVs.
More generally, the experience of the NanoCap
project may be helpful for organizing public debates
on the development of nanotechnologies and on their
implications for society.
ACKNOWLEDGMENTS
The capacity building project NanoCap was
granted by the European FP6, Science and Society
Program, grant no. SAS-CT-2006–036754-NanoCap.
Further elaboration of the results was made possible by a grant of the UvA Holding BV. The helpful
comments of the unknown reviewers are gratefully
acknowledged.
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58
Chapter 3 Use of nanomaterials in the European construction
industry and some occupational health aspects thereof Published in: Journal of Nanoparticle Research (2011) 13:447–462
59
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60
Use of nanomaterials in the European construction industry
___________________________________________________________________________________________
and some occupational health aspects thereof
Pieter van Broekhuizen •
Fleur van Broekhuizen •
Ralf Cornelissen • Lucas Reijnders
Received: 18 August 2010 / Accepted: 20 December 2010
Springer Science+Business Media B.V. 2011
reference values proposed on the basis of a precautionary approach.
Abstract In the European construction industry in
2009, the use of engineered nanoparticles appears to be
confined to a limited number of products, predominantly coatings, cement and concrete. A survey among
representatives of workers and employers from 14 EU
countries suggests a high level of ignorance about the
availability and use of nanomaterials for the construction industry and the safety aspects thereof. Barriers
for a large-scale acceptance of products containing
engineered nanoparticles (nanoproducts) are high
costs, uncertainties about long-term technical material
performance, as well as uncertainties about health
risks of nanoproducts. Workplace measurements suggest a modest exposure of construction workers to
nanoparticles (NPs) associated with the use of nanoproducts. The measured particles were within a size
range of 20–300 nm, with the median diameter below
53 nm. Positive assignment of this exposure to the
nanoproduct or to additional sources of ultrafine
particles, like the electrical equipment used was not
possible within the scope of this study and requires
further research. Exposures were below the nano
Keywords Nanomaterials Construction industry Awareness Risk assessment Exposure
measurements Nano reference values Occupational health EHS
Introduction
Nanotechnology creates possibilities to produce construction materials with novel functionalities and
improved characteristics. An overview of current
nanotechnologies research for the construction industry has been presented (NICOM3 2009; Lee et al.
2009; Ge and Gao 2008). Applications of nanotechnology have been described for cement, wet mortar
and concrete, paints, and coatings (NICOM3 2009),
insulation materials (Insulcon 2009; Relius 2009;
Aspen 2009), glass (Econtrol 2009; 3M 2009; SaintGobain 2009) and infra-structural materials (Eurovia
2008; Bijl 2008). Nanoparticles (NPs) have been
claimed to reduce the weight of concrete by using
silica fume (an aggregate of amorphous SiO2 nanoparticles), to increase strength and elasticity of
concrete, to save energy consumption of houses by
improved performance of isolation materials, to
improve weathering properties for exterior surfaces,
as self cleaning coatings for interior and exterior
surfaces and window glass, as traffic exhaust
P. van Broekhuizen (&) F. van Broekhuizen R. Cornelissen
IVAM UvA BV, Plantage Muidergracht 14,
1018TV Amsterdam, The Netherlands
e-mail: pvbroekhuizen@ivam.uva.nl
L. Reijnders
University of Amsterdam, Institute for Biodiversity
and Ecosystem Dynamics, Amsterdam, The Netherlands
61
___________________________________________________________________________________________
purification coatings for infrastructural works, to
provide better crack resistance of polymer materials,
as biocidal surfaces for walls of surgery rooms, to
improve fire resistance of materials, etcetera. NanoTiO2 in concrete is explored with the aim to enhance
its’ durability and to maintain whiteness throughout
the entire lifetime of the construct. It is claimed that
organic pollutants, microorganisms and NOx are
broken down by the photo-catalytic activity of
TiO2. The efficient performance of nano TiO2 for
road coating systems or coating of acoustic fencing
along motorways has not been substantiated in
practice, though (van Ganswijk 2009).
More advanced, ‘‘smart’’ developments have been
reported, including building materials containing
nano-sensors, and nanoparticulate self-repairing materials (Koleva 2008; Yang et al. 2009). Some of the
applications of nanotechnology have already reached
the market; many are still under development. Actual
uses of these applications in buildings have been
described (Hessen Agentur 2007; Leydekker 2008).
Occupational exposure to NPs may have an impact
on health. Indications for human health hazards have
been reported by many research groups showing
oxidative stress, fibrosis, cardiovascular effects, cytotoxicity, and possibly carcinogenicity as effects of
nanoparticle exposure (Renwick et al. 2004; Borm
et al. 2006; Schneider 2007; Schulte et al. 2008;
Borm et al. 2008; Trouiller et al. 2009; Knol et al.
2009; Stone et al. 2010, b). Findings, e.g., suggest
that metal oxide nanoparticles affect the cardiovascular system and may inflict DNA damage. The
pulmonary response to nanoparticulates in general
has been demonstrated to be inflammogenic in nature,
with epithelial damage, oxidative stress and cytotoxicity, driven by particle mediated ROS (reactive
oxygen species) production, being common findings.
At present there is only very limited information
about the availability and actual use of nanoparticulate products and about possible exposures to NPs
released from these products at the workplace. To
date, exposure to engineered NPs in practice is
limitedly reported in scientific literature for research
activities and to an even lesser extent for workers in
NPs manufacturing or nanoproducts’ use.1 Reports on
the exposure of downstream use workers to NPs are
rare (Schneider 2007; Berges 2009; Brouwer et al.
2009; Plitzko 2009; Methner et al. 2010a; Methner
et al. b). Insight in exposure to NP in practice when
NPs are emitted from products, which contain a solid
matrix, is limited. Mechanical abrasion tests quantifying the nanoparticle release into air from dried
surface coatings show that there is no significant
correlation to nanoparticle content. NPs remain
embedded in the coarse wear particles (Vorbau
et al. 2009; Göhler et al. 2010). Also, Koponen
et al. (2010) were not able to detect a clear effect of
ENPs on dust emissions from sanding ‘‘nanopaints’’
in a standardized testing situation.
Against this background this paper addresses the
following questions:
1.
2.
3.
4.
Which nanoparticulate products are used in the
European construction industry?
Are employers and employees aware of the
nanoparticulate character of those products and
of its implications for occupational health?
What are actual exposures to nanoparticles in a
limited number of working environments where
workers deal with nanoproducts?
How do these exposures compare with preliminary nano reference values for workplace exposure based on a precautionary approach?
In the characterisation of nanoparticles a distinction is made between engineered nanoparticles
(ENPs) and ultrafine particles (UFPs). Both are in
the same size range, but ENPs are nanoparticles
that are industrially manufactured and used in
products to add a specific functionality. UFPs are
nanoparticles with a natural origin or nanoparticles
with an anthropogenic origin generated as byproduct of human activities, such as burning fuel
or drilling. If no distinction is being made between
these two types the term ‘‘nanoparticles’’ (NP) is
used.
Concerning the nanoparticle size the draft definition, as published by the European Commission
(2010) for ‘‘nanomaterial’’ is used. This definition
considers three different possibilities, of which the
first is used in this study: Nanomaterial means a
material that meets the following criteria: consists of
particles, with one or more external dimensions in the
size range 1–100 nm for more than 1% of their
number size distribution.
1
In this article, a nanopoduct is considered to be a product in
which engineered nanoparticles are used to influence the
specific properties and to improve the performance.
62
___________________________________________________________________________________________
Materials and methods
The insight gained in the development and use of
nanoproducts in the construction industry was further
deepened by in-depth interviewing of construction
employers and workers, architects, raw material, and
product manufacturers as well as R&D scientists, in
total ca 45 interviewees from Western European
countries and 5 from the USA and Canada.
Inventory European nanoproducts market
Within the European social dialogue in the construction industry the association of employers organisations FIEC2 and the association of trade unions
EFBWW3 together did set up an inventory of the
current availability and use of nanomaterials and
nanoproducts at European construction sites. This
inventory aimed to provide insight into barriers and
drivers for the use of nanoproducts in this sector and to
identify related occupational health and safety issues.
The FIEC represents 34 national member Federations
in 29 countries (27 EU and EFTA, Croatia and
Turkey), construction enterprises of all sizes, i.e.,
small and medium-sized enterprises as well as ‘‘global
players’’, carrying out all forms of building and civil
engineering activities. The EFBWW is the European
Industry Federation for the construction industry, the
building materials industry, the wood and furniture
industry and the forestry industry. The EFBWW has
75 affiliated unions in 31 countries and represents a
total of 2,350,000 members.
Part of the inventory was a questionnaire set out by
the FIEC and the EFBWW among their members in
24 European countries (hereafter called the 2009survey). A strategic selection of 144 well-informed
FIEC and EFBWW contact persons in the Member
States resulted in 28 completed questionnaires from
14 European countries. Completeness was not pursued, as this would require a much more elaborate
approach. The aim was to get an impression of the
actual use of nanoproducts in the European construction industry and of the communication about technical performance and health and safety issues
regarding nanoproducts in the sector.
Literature research and an extensive web search
generated further insight in the use of nanomaterials
and communication about potential related occupational health risks.
Preliminary exposure measurements
Exposure to NPs dispersed during use of nanoproducts was measured at two different companies for a
total of four different working situations: 1 spraying a
liquid window coating, 2 and 3 applying a cement
repair mortar and 4 nano-concrete drilling.
All exposure measurements are carried out with an
Aerasense NP monitor (NanoTracer): a portable
aerosol sampler of Philips Aerasense, Eindhoven,
and The Netherlands. The NanoTracer provides real
time information about the number concentration
(particles per cm3), number-averaged particle diameter and surface area. The apparatus detects NP’s
within a range of 10–300 nm, as an arithmetic mean
in time intervals of 16 s or less, depending on the
selected modus. The accuracy is considered to be ca.
10%. The apparatus technical details of the Aerasense
NP monitor were described by Marra et al. (2007;
2010).
On board data logging capabilities were utilized
for the Aerasense NP monitor. A laptop computer
with software was used for both control and data
acquisition (NanoReporter 1.0.2.0, Philips Aerasense,
Eindhoven, The Netherlands) and data analysis
(NanoReporter 1.0.2.0 and MS Excel, Microsoft
Corporation, United States). All aerosol NP monitors
used were time synchronized with the laptop prior to
commencement of sampling. Statistical analysis was
carried out with the statistics programme Stata.
Personal exposure assessment and source identification measurements were carried out during all
described activities. Personal monitoring was carried
out with a NanoTracer fixed at the belt of the worker.
Natural background concentrations were measured at
the workplace preceding the activities using nanomaterials. Near-field emission (within 1–2 metres from
activities) measurements were carried out with a
second NanoTracer operated hand-held by of one of
the authors. During all observed activities, the
workers wore FFP3 protection masks.
2
FIEC Fédération de l’Industrie Européenne de la
Construction.
3
EFBWW European Federation of Building and Wood
Workers.
63
___________________________________________________________________________________________
Working situation 1
Company 1 specialised in the application of water
based self-cleaning and antibacterial coatings for
exterior and interior hard surfaces: walls, windows,
and horizontal surfaces. According to the technical data
of the product the active nano-component is TiO2
(anatase) with an initial particle diameter of\8 nm and
a BET 160 ± 30 m2/g.4 For application a paint spraying system is used (Wagner W850F). The actual
activities concerned the application of the self-cleaning
coating on the exterior windows (approx. 75 m2 glass)
of a small rural detached house (see Fig. 1). One worker
applied the coating, during 1 h. The activities carried
out were the filling of the spraying system with 1 L premixed coating dispersion, followed by the spraying
activities. In total ca 250–330 mL coating was used,
with an estimated use of 17 mg nano-TiO2. The electric
generator of the spraying system was placed at
approximately 1.5 meter distance of the personal
monitoring equipment. The weather conditions were
dry with a mild wind (approximately 3 Beaufort).
Fig. 1 Spraying the self-cleaning coating on a window
(Company 1)
Working situation 2
Company 2 is specialised in concrete repair in civil
works situated in or nearby water, especially bridges
and viaducts. The company uses concrete mortar with
nano-filler for repairing large damaged surfaces and
for applying a concrete covering on reinforced steel
(rebar). The mortar material used is Emaco NanoCrete R4. According to the supplier, the product
contains ‘‘applied nanotechnology’’ that provides
elasticity to the mortar, and prevents the development
of cracks. Neither the technical data sheet, nor the
Material safety data sheet (MSDS) provide information on the exact nature of the nanomaterial present.
However, according to direct information from the
manufacturer, the nanocomponent in NanoCrete is
highly agglomerated fumed silica with a size
of [ 100 nm (BASF 2009, personal communication).
The MSDS does not mention any nano-related
measures. The actual work concerned the manual
repair of a limited surface area at the underside of a
concrete bridge (see Fig. 2). Deteriorated concrete
parts were pneumatically removed, after which
4
Fig. 2 Manual concrete repair at the underside of a bridge
(Company 2, location 1)
Technical product information of the product Environ-X,
provided by the supplier NanoServices.
64
___________________________________________________________________________________________
measure NPs generated by the electrical equipment,
measurements were carried out immediately next to
the idle running mixer. Electric power for the
equipment used was generated by a diesel generator,
which was situated at approximately 25 metres from
the construction site, adjacent to the workers canteen.
Cigarette smoking workers generated an additional
source of exposure to UFPs (ultrafine particles).
NanoCrete was applied manually. The total amount
NanoCrete used was 25 kg, which was mixed with
water, resulting in ca 11 L mortar. The mixing itself
had a duration of 3 min; the period used to apply the
mortar was 35 min. Electric power for the equipment
used was generated by a diesel generator, which was
situated at approximately 15 metres from the construction site. The weather conditions were dry with a
mild wind (approximately 2 Beaufort).
Working situation 4
Working situation 3
At location 3 the same company 2 re-enacted drilling
activities in cured concrete mortar. Measurements
were carried out during drilling work in a concrete
wall in the open air, at the companies’ headquarters.
Measurements were carried out during drilling in
conventional concrete as well as in a wall that that
was constructed with NanoCrete mortar. In addition
to the measurements during drilling, a measurement
was carried out immediately next to the drill, while it
ran idle, to measure NPs generated by the electric
equipment. During all activities the weather conditions were dry, with a relatively strong wind,
approximately 5 Beaufort. In all cases (drilling and
idle- running) one NanoTracer was located ‘upwind’
and one ‘downwind’ at approximately 0.5 metres
from the employee.
At another location of company 2, at another day,
measurements were carried out during mixing of
shotcrete repair mortar at a repair work at a concrete
bridge. The product used was the same concrete
repair mortar as used in working situation 2. The dry
mortar was dosed from 25 kg bags into a vessel, and
mixed with water by means of a long-stemmed mixer
(see Fig. 3). Subsequently, the wet mortar was
pumped through a hose and pneumatically projected
at high pressure onto the surface of the bridge. The
actual spraying activities were not monitored. During
mixing and spraying, the workers wore P3-dust
protection masks. During all activities the weather
conditions were dry, with a relatively strong wind of
approximately 5 Beaufort. In addition to the measurements of activities involving nanomaterials, to
Results
Market survey
In Table 1 an overview is given of typical nanomaterials offered at the market for actual use in the
European construction industry in 2009, as identified
in the interviews and the inventory. In total 94 different
products were identified (Broekhuizen et al. 2009).
Table 1 shows that only a few types of NPs
dominated the use of NPs in construction materials in
2009. Nano- TiO2, ZnO, aluminium oxide, Ag, and
SiO2 are predominant. No evidence was found for the
use of carbon nanotubes (CNT) in construction materials neither in coatings nor in cementitious or concrete
products; this despite the intensive ongoing research
and the claimed high potential of CNT to positively
influence the specific performance of products.
Coating products were identified to dominate the
market, being 68% of the total number of the
Fig. 3 Mixing concrete repair mortar (Company 2, location 2)
65
___________________________________________________________________________________________
Table 1 Nanomaterials actually applied in construction materials (2009)
Material
Functionality introduced
Nanoparticle
Type of introduction
Concrete
Self-cleaning surface (photo-catalytic)
Increased durability
TiO2
Surface layer
Ultra strong concrete
SiO2 (silica fume)
Mixed in matrix, filler to
improve material strength
Aerogel, often SiO2 or
carbon based
Corrosion reduction
Insulation material
Improved insulating properties against
heath, cold, fire or a combination thereof
Nanoporous material#
Coatings##
Improved surface penetration, coverage
Reduced layer thickness
Nano-sized dispersions
Transparent coatings
Photo-catalytic, self-cleaning, hydrophobic properties
Nano-sized ingredients
TiO2, ZnO, SiO2
Glass
Additive in the coating
Anti-bacterial
TiO2, ZnO and Ag
Scratch resistance
SiO2, Aluminium oxide
Easy-to-clean surfaces
Carbon fluorine polymers
Fire retardant
TiO2, SiO2 and nano-clays
UV-protection of wood
TiO2, ZnO, CeO2,
Decolourisation of wood by tannin
Nano-clays
IR-reflection
Tungsten oxide
Surface coating
Non-reflective glass
Nano-porous surface SiO2
Surface structure
Fire or heat protection
Metal oxides SiO2
Surface coating
Surface coating
Transparent silica gel
inter-layer between two
glass panels
Infrastructure
#
Easy-to-clean properties
Ag, SiO2, carbon fluorine
polymers
Surface coating
Photo-catalytic self cleaning properties
TiO2
Surface coating
UV active air pollution reduction on
asphalt, road pavement blocks, sound
barriers and tunnels
TiO2
Surface coating
The internal structure consists of nano-bubbles (nano-holes)
##
Coatings with similar functionalities are developed for many different material surfaces like wood, plastic, metal, concrete, glass,
ceramics and natural stone
The inventory of nanomaterials applied in the European construction industry is the result of a questionnaire held under 144 members
of FIEC and EFBWW in 24 EU-countries. The response was 28 answers from 14 countries. To this inventory data were added from
in-depth interviews with 50 manufacturers and end-users in the EU and an extensive web search on nanoproducts that are marketed in
the European construction industry
identified nanoproducts. Coatings also included products like a top coating for road pavement or a top
coating for concrete products. Concrete and cement
products and insulation products made up for 12 and
7% of all the identified products.
According to the interviews, silica fume-based
cement (amorphous silica) appears to be a successful
nano-niche. Silica fume does improve the particle packing of the concrete matrix resulting in improved
mechanical properties, reduced water permeability and
a higher durability (NICOM3 2009). However, its production process and the high demands placed on the
equipment to handle silica fume cement cause silica
fume to be more expensive for use than alternative cement
types. As a result, silica fume is only applied on specific
customer demand or if regulation does require so.
EU wide rough estimates, made by interviewed
experts, suggest that silica fume UHPC (Ultra High
66
Company 2,
location 1
Mixing mortar
Company 2,
location 2
Mixing and
handling
repair mortar
Company 2,
location 3
Drilling cured
concrete mortar
2
3
4
67
24
Background in workers canteen
11
9
9
12
Drilling in normal concrete, near field
Drilling machine idle-running
Background
13
Drilling machine idle-running
Drilling in NanoCrete concrete, near field
11
7
Drilling in NanoCrete concrete, near field
Drilling in normal concrete, near field
5
107
Background
Direct emission mixer
52
Personal exposure: (NanoCrete mixing)
23
26
9.512
5,611
10,075
10,656
7,043
9,743
7,886
7,416
6,896
59,957
5.964
6.107
45,429
6,177
7.195
16.337
11.346
66.079
572.410
164.424
83.545
20.068
52.732
114.962
115.011
13.310
71.519
641.074
73.928
15.696
11.832
7.643
12.319
88.688
55.865
43.460
18.549
35.966
9.318
80.450
8.738
10.985
123.931
11.412
11.907
12.219
7.605
22.889
195.616
70.981
39.033
15.960
29.545
49.978
79.619
8.844
13.983
199.508
20.763
11.898
34
34
24
19
19
21
34
22
19
25
20
21
23
27
31
54
40
300
97
59
48
223
94
70
184
300
173
65
207
174
Max
(nm)
48
37
44
43
40
44
51
47
44
47
51
47
47
54
53
Median
(nm)
45
32
74
51
32
42
107
48
43
57
69
62
41
49
59
AM
(nm)
The NanoTracer detects NP’s within a range of diameters of 10–300 nm as an arithmetic mean in time intervals of 16 s
Measurements at four outside locations in the construction industry were carried out using two NanoTracers, one for personal monitoring and one to measure the concentration of
NP in the near field (as in situation 4, respectively the down- and up-wind concentration). The near field is defined as a distance of 1–2 m from the activities with dispersive use of
nanomaterials. The background for situations 1, 2 and 3 was measured preceding the activities using ENPs. The background for situation 4 was measured at larger distance in
up-wind position. Direct emissions from idle-running electrical equipment were measured without the use of products containing ENPs. The nanomaterial used in situation 1
concerns a waterborne suspension of Nano-TiO2, while situations 2 and 3 concern the mixing of dry nanomaterial. Situation 4 concerns release of NPs from drilling activities in
cured concrete
NP/cm3 number of nanoparticles/cm3, nm nanometres
AM
(NP/
cm3)
Min
(nm)
Median
(NP/
cm3)
Min
(NP/
cm3)
Max
(NP/
cm3)
Diameter nanoparticles
N amount of measurements, Min lowest measured value, Max highest measured value, AM arithmetic mean
Down-wind location
Up-wind location
SiO2 (amorphous)
NanoCrete R4
Personal exposure: (NanoCrete mixing)
Background
Background
SiO2 (amorphous)
NanoCrete R4
83
185
Personal exposure during spray activities
TiO2 (anatase)
Company 1:
Spraying
self-cleaning
coating
1
N
Number of nanoparticles
Workers exposure to nanoparticles
Measurement Location
ENP
Working situation
Table 2 Exposure measurements to NPs at some construction sites
___________________________________________________________________________________________
___________________________________________________________________________________________
measurements, and corrected for the local background concentration (see Table 2)
Table 3 Background-corrected 8-h TWA exposures to NPs.
The 8-h TWA exposure was calculated based on the actual
working period with products containing NP at the days of the
Working situation
1
Company 1, Spraying
self-cleaning coating
2
Company 2, location 1
Mixing mortar
3
Company 2, location 2
Mixing and handling
repair mortar
Measurement location
Personal exposure during spray
activities
Exposure
time
(h)
AM
(Np/cm3)
Mean 8-h
TWA
(Np/cm3)
1.25
12.219
50
Background
11.898
Personal exposure: (NanoCrete
mixing)
0.05
Background
199.507
1.117
20.763
Personal exposure: (Nanocrete
mixing)
0.5
Background
13.983
321
8.844
Table 4 IFA proposed benchmark levels
Description
Density
1 CNT with a high aspect ratio
([3:1), length [ 5.000 nm,
insoluble
Benchmark level
(Nano reference
value) (8-h TWA)
Type NP
0.01 fibres/cm3
(10.000 fibres/m3)
• CNT, for example asbestos-like SWCNT or
MWCNT without specific toxicity information
of the manufacturer
2 Metals and metal oxides and
other biopersistent granular
nanomaterial
in the range of 1 and 100 nm
[6.000 kg/m3
20.000 particles/cm3 • Ag, Au, CeO2, CoO, Fe, FexOy, La, Pb, Sb2O5,
SnO2,
3 (Metals and metal oxides and
other) biopersistent granular
nanomaterial
in the range of 1 and 100 nm
\6.000 kg/m3
40.000 particles/cm3 • Al2O3, nanoclay, SiO2, TiN, TiO2, ZnO
4 Ultrafine liquid and soluble
particles
• Carbon Black, C60, dendrimers, polystyrene
• CNT with explicitly excluded asbestos-like effects
Applicable OEL
Performance Concrete; *4w/w% silica fume)
makes up for 5% of the concrete market, which
comes down to approximately 3.6 Mtons of silica
fume concentrated in relatively few special construction projects. Raw material silica fume generally is highly agglomerated (Evonik Rheinfelden
2008, personal communication; BASF 2009, personal
communication).
The interviews indicate further that the actual use
of titanium dioxide NPs in concrete is limited,
typically reserved for those types of concrete that
can be manufactured as bi-layer systems and for
which a relatively high unit price can be asked (2009,
personal communication). Photo-catalytic cement
products like concrete blocks, bricks, tiles or roof
• e.g., fats, hydrocarbons, siloxanes, NaCl
tiles are just about to appear on the market, their
actual use is still small. Because of its lower costs and
similar, but less reactive characteristics, microcrystalline TiO2 (particles [ 100 nm) is used more frequently than the nano-TiO2 (Heidelberg Technology
Center Germany 2009, personal communication).
Other TiO2 containing products are photo-catalytic
cement products for the construction of exterior walls,
facades and tunnels (Heidelberg Technology Center
Germany 2009, personal communication; ItalCementi
2009), binders for coating materials for concrete
floors, paving blocks, tiles, roof tiles, road marking
paints, concrete panels, plaster, and cementitious
paints (ItalCementi 2009), and coating for natural
stone and concrete surfaces (Nanogate 2009).
68
___________________________________________________________________________________________
received from respondents (see Box 1) and statements
obtained from the in-depth interviews does indicate
that the actual market penetration anno 2009 is still
low and limited to a rather few niche products.
Interviewees state that high costs and uncertainties
about long-term technical material performance of
nanoproducts are a barrier for large-scale acceptance
(BASF 2009, personal communication; Heidelberg
Technology Center Germany 2009, personal communication; Skanska 2009, personal communication).
Interviewees emphasize further that health and
safety issues remain barriers to be overcome prior to
market application (Makar 2009, personal communication; NanoCyl 2009, personal communication;
BASF 2009, personal communication; Bayer 2009,
personal communication). Not only the toxic (asbestos-like) effects identified for specific long multi wall
carbon nanotubes (Poland et al. 2008a, b; Takagi
et al. 2008) trigger end-users to postpone the use of
nanomaterials. Also the uncertainty about the toxicity
of spherical shaped nanomaterials influence this
attitude (2009, personal communication).
For the decorative paints industry, the following
high performance construction coatings and coatings
with specific nano-modified properties can be identified on the market: anti-bacterial coatings (Bioni
2008), photo-catalytic self cleaning coatings (Clou
2009), UV and IR reflecting or absorbing coatings
(BASF 2009 personal communication; Byk 2009),
fire retardant coatings and scratch resistant coatings.
Nanoclay (i.e., hydrotalcite) is used in wood coatings
to prevent wood ‘‘bleeding’’ by tannins that, in time,
decolorize the wood surface (Byk 2009). Coating
applications for glass and wood benefit especially
from the transparency of NPs to visible light. In the
case of glass, one finds ‘‘baked-on coatings’’ applied
during the glass production process and sprayed-on
coatings applied on-site.
Insulation materials called ‘nano’ are often made
out of a nano-foam (or aerogel), containing nano-size
holes (Insulcon 2009). On the market are: nanostructured fluoro polyurethane products (combined
with a photo catalytic iron oxide top layer) for heat
and cold protection (BASF 2009, personal communication; Relius 2009). There are also nano-porous
silica structure insulation materials produced for fire
protection (Aspen 2009), as well as materials for
sound isolation (BASF).
Information supply
The primary source of hazard information for downstream users is the MSDS. However, from the
respondents 37% answered that general hazard
information was provided via the MSDS or the
product label, but that very limited, if any, information was supplied on the nano-additive in the product.
Kittel (2009) describes comparable findings for the
situation in Austria.
Current legislation does not oblige manufacturers
and suppliers to report the level of NPs contained in
the product to the downstream user, but as in-depth
interviews point out, there is also confusion about the
definition of NPs, nanomaterials and nanoproducts,
resulting in conflicting opinions about characterizing
the supplied material as ‘‘nano’’ or not. As was
Awareness
The 2009-survey indicates that 80% of the workers’
representatives and 71% of the employers’ representatives were not aware of the availability of nanomaterials and were ignorant as to whether they actually
use nanomaterials at their workplace.
This high level of ignorance makes that no strong
conclusions can be drawn from the survey results
alone with respect to the market penetration of
nanoproducts in construction. Nevertheless, combining the responses from workers and employers that
did work with nanomaterials, with several comments
Box 1 Citations from the 2009-survey on awareness
‘‘…I have spoken to a number of companies regarding this subject and no one is aware of any materials containing these products.
I have also spoken to a number of people from the Health and Safety Executive and they are also not aware of the existence of
these products. I would be happy to receive further information regarding this issue so that I can investigate further (UK),’’
‘‘…we tried to get information from several construction-subsectors, but until today we didn’t receive useful indications.
The problem (and we are not very surprised) is still unknown (CH),’’
‘‘…the subject is simply too abstract and too unfamiliar to respond to the survey at all (NL)’’
69
___________________________________________________________________________________________
stressed in the interviews, the time that a ‘‘nano-tag’’
was a good product selling argument is over;
uncertainty about possible health or environmental
effects prevails. As a consequence, to prevent a
negative impact on the sales, products are now
predominantly marketed without referring to the
nano-size. In industry the terms ultrafine (Stone
et al. 2010a, b) and sub-micron particles (Sprietsersbach 2010) are frequently used. The market may now
face a growing number of downstream users who are
not informed about the type and content of NPs in the
products they use.
Particle concentration (Np/m3)
20000
15000
10000
5000
background
spraying nano coating
Fig. 4 Boxplot of the particles concentration measured during
application of the self-cleaning coating. The plot shows the
minimum, the 25% percentile, the median value, the 75%
percentile and the maximum particles concentrations. The
background and the spraying activities are in the same order,
although the amount of measured NPs for the spraying
activities is slightly higher
Exposure measurements
Results from the exposure measurements are presented in Table 2. From the measurements in the four
working situations it is evident that sources of UFPs
such as the electric mixer, the drill, the diesel
aggregate or cigarette smoke may well dominate
over ENPs exposure at the construction site as
generated by the use of nanoproducts. It is uncertain
whether the NPs released from the NanoCrete R4 in
the mortar are ENPs. Due to the claimed highly
agglomerated state of the silica fume in the NanoCrete R4 in situations 2, 3, and 4, the amount of free
ENPs in the prepared mortar may be very limited.
Nevertheless release (de-agglomeration) of ENPs
might occur under the high-energetic activities like
drilling, but confirmation as this can only be given by
chemical analysis of the particles and a more
thorough analysis of the particle size distribution.
At all measured outside locations there is a large
variation in the airborne concentrations. The minimum and maximum concentration may differ by a
factor 50, as measured for the idle-running drilling
machine at location 3 of company 2. An explanation
for this strong variation might be the strong influence
of turbulences in the outside air on the airborne NPconcentration. The short, sometimes very high peak
exposures generated by short-term activities like
adding nanosized mortar and the subsequent mixing,
are quickly diluted by the outside air turbulence.
Table 2 also shows the diameters of the measured
nanoparticles, measured as the arithmetic mean of the
particles diameter averaged over time intervals of 16 s.
Measured particles vary in minimum and maximum
diameter between 19 and 300 nm (probably larger than
300 nm as well, which is the detection limit of the
used equipment). Larger NPs are likely to be formed
by agglomeration. The arithmetic mean of the particles’ diameter in the personal exposure measurements
varies from 59 to 69 nm. For the drilling activities a
larger arithmetic mean is measured, but the median is
comparable. The median for the different situations
varies between 37 and 54 nm.
The measurements carried during the spraying of
the self-cleaning coating are presented in boxplot (see
Fig. 4). A slightly elevated particles concentration is
observed during these activities. A distinction between
exposure to ENPs derived from the coating and those
NP possibly generated by the electrical motor of the
spraying equipment cannot be made at this stage.
During the mixing of mortar a high emission of NP
is possible, as is shown with a peak exposure
of [ 600.000 Np/m3 for the single use of one 25 kg
bag of NanoCrete at the location 1 of company 2. At
the second location the measured exposures, during
the mixing of 6 bags, were much lower, probably
largely influenced by the weather conditions. These
measurements are shown in Fig. 5 of which a boxplot
is presented in Fig. 6. In this situation, with a
relatively strong wind, peak exposures did not exceed
72.000 Np/cm3. Independently, a peak exposure of
almost 115.000 Np/cm3 is measured for an idle
running mixer (see Table 2). For the series of short
peak exposures no distinction can be made between
exposure to ENPs dispersed from the mortar-mix and
UFPs generated by the electrical mixer equipment.
At the same location separate measurements were
carried out of the exposure to NPs in the workers
70
___________________________________________________________________________________________
80000
Particle concentration (Np/cm3)
Fig. 5 Exposure to NPs
during mixing mortar in
company 2, location 2. The
figure shows the results of
personal monitoring of the
adding of 6 NanoCrete bags
and the consequential
mixing of the mortar (time
is represented in seconds).
The actual mixing activities
took place in the time
interval between 565 and
2493 s. Just before this
period, in the time interval
between 235 and 565, a
smoking colleague visited
the working site, which
resulted in a short peak
exposure of the worker of
60.000Np/cm3
60000
40000
20000
0
0
235
565
2493
3170
Particle concentration (Np/cm3)
time
both at a distance of 0.5–1 meter from the drilling
worker (se Table 2). For drilling in cured NanoCrete
concrete the arithmetic mean NP concentration for the
downwind position exceeds the concentration in the
up-wind position by 40,000 Np/cm3. For drilling in
‘normal’ concrete this difference is ca. 16,000 Np/cm3.
The median values for these situations differ 20.000
Np/cm3 and 6.000 Np/cm3, respectively. The NPs
emission generated by drilling in NanoCrete concrete
is 2–3 higher than the emission of drilling in ‘‘traditional’’ concrete, suggesting a higher release of NPs
from the NanoCrete concrete. At the same time a
control measurement shows that the emission of NPs
from the idle-running drill in this situation may be as
high as [ 600,000 Np/cm3 in the downwind position,
indicating that the higher emission during the NanoCrete-concrete drilling may as well be caused by
engine-generated NPs from the higher drilling intensity in the denser NanoCrete concrete.
80000
60000
40000
20000
0
background
mixing mortar
Fig. 6 Boxplot of the particles concentration during mixing of
mortar at company 2, location 2. The plot shows the minimum,
the 25% percentile, the median value, the 75% percentile and
the maximum particles concentrations, including outliners
representing the short-term peak exposures during the actual
mixing of NanoCrete. The exposure during mixing of mortar is
clearly distinguishable from the background
canteen and of the emission of NPs of the diesel
aggregate (see Table 2). The workers’ exposure in
the canteen shows a high average personal exposure
to NPs, of nearly 80.000 NP/cm3, with peak exposures of [ 110.000 NP/cm3, likely to be generated by
(indoor) smoking workers. A contribution to the
indoor NP concentration, however, may also be
generated by the diesel aggregate that was standing
adjacent the canteen.
For the drilling of cured concrete (company 2,
location 3) the near field concentration of NPs was
measured in an up-wind and a down-wind position,
Personal exposure 8-h TWA
A mean 8-h TWA (time weighted average) personal
exposure to NPs, corrected for the background
concentration of NPs, can be calculated assuming
that no other activities with this nanomaterial are
carried out during the working day. For working
situation 1 this means no further spraying activities,
for situation 2 and 3 no further mixing of NanoCrete
containing mortar. For working situation 4, the
71
___________________________________________________________________________________________
drilling in concrete, no 8-h TWA was calculated
because this was specifically arranged to test the
generation of NPs and does not represent a real-life
drilling activity. In all cases the calculated 8 h-TWA
exposures to ENPs (including engine-generated NPs)
are an estimate of the apportionment of workplaceemitted particles to the total particles concentration.
The calculations are presented in Table 3.
For the situation 2 and 3, in company 2, the level
of the background corrected 8 h-TWA exposure to
workplace-generated NPs is largely determined by
the short-term peak exposures of handling the
nanoproduct. The exposure may be a mix of ENPs
released from the nanoproduct and UFPs generated
by the electrical equipment.
at the workplace. When exceeding this level the source
of the nanoparticles’ emission(s) should be thoroughly
identified and possibilities to reduce the emission of
nanoparticles must be assessed. The NRVs are based
on the benchmark levels as proposed by (IFA 2009;
Schulte et al. 2010) and quantified as 8-h TWA (time
weighted average), corrected for the background
concentration as shown in Table 4:
For the measured workplace situations 1–3 in
which nano-TiO2 or fumed silica may be emitted,
both metal oxides with a density of \6.000 kg/m3,
the values in Table 4 would imply a (background
corrected) level of the NRV of 40.000 particles/cm3.
All the calculated 8-h TWA exposures (see Table 3)
remain well below the NRV level, suggesting that for
the specific workplaces of this study and their actual
conditions no extra measures would have been
necessary additional to the measures that were
already required based on the risk assessment of the
other (bulk and molecular) materials used.
Comparison of measured values with nano
reference values
Based on what is known today tools have been
published to help to design a safe nano-workplace
(Schulte et al. 2008; VCI 2007; Borm et al. 2008;
NanoSafe 2008; NanoSmile 2010), including the use
of control banding tools (Paik et al. 2008; Höck et al.
2008).
Ignorance about possible risks and the lack of
essential health and safety information of the downstream user might be argued to call for a precautionary
approach in risk assessment and risk management.
Building blocks for a precautionary approach were
adopted by the construction employers’ organization
and the trade unions (Broekhuizen and Reijnders
2010; FIEC-EFBWW 2009). The question, which
arises in this context, is what is an acceptable
precautionary exposure level? As for ENPs
HBR-OELs5 or DNELs6 are not available, temporarily
precautionary reference values are being developed in
The Netherlands, called nano reference values (NRV)
(Dekkers and Heer 2010). A NRV is defined as a
warning level and refers to the ENP-concentration in
the workplace atmosphere, corrected for the background NP concentration. It is intended to be a warning
level to trigger a thorough assessment of nanoparticles
Discussion
The high expectations for nanotechnological products
for the construction industry, as mentioned in scientific literature and market studies (Freedonia 2007),
are as yet not reflected by practice. Limited communication in the production chain about technical and
health and safety aspects of these products is
observed. Costs and the present uncertainty regarding
long-term technical performance of nanoproducts are
factors that limit the use of nanoproducts in the
European construction industry. At the moment
nanomaterials and thus nanoproducts are significantly
more expensive than their non-nano alternatives.
Manufacturers of construction materials are reluctant
to develop nanoproducts, especially when the performance of existing non-nanoproducts is believed to be
sufficient. This holds in particular for the larger
volume products like concrete or mortar and for
construction coatings. Nanoproducts, as a result,
remain niche products that are only applied upon
specific request.
A larger potential in the future is expected for
insulation materials, architectural and glass coatings
that have the improvement of the energy performance
of the construct as their main objective. These are
currently niche markets, but the current focus of
5
HBR-OEL Health-based recommended occupational exposure limit. (maximum permissible concentration of a given gas,
vapor, fiber or dust in the air at the workplace).
6
DNEL Derived no-effect level. (Within REACH the level
above which humans should not be exposed).
72
___________________________________________________________________________________________
the denser concrete structure of the NanoCrete
provokes a higher drilling intensity, resulting in an
increase in engine-generated NPs. As anticipated by
Maynard and Zimmer (2002) and shown by Szymczak et al. (2007) electric equipment is a source of NPexposure that cannot be neglected. In a test system
Szymczak found a significant emission of Cu NPs up
to 3.0 9 1011 particles/m3, generated by universal
motors as used in domestic and do-it-yourself electrical equipment, including a drilling machine. Chen
et al. (2006) and Meng et al. (2007) have reported
about the high reactivity and acute toxicological
effects of copper nanoparticles. This emphasizes the
need to take Cu-NP exposure also into consideration
when making a risk assessment.
The emission of NPs from the electrical equipment
shown here and reported elsewhere (Szymczak 2007)
is of the same order of magnitude as, or larger than
the measured on-site exposures. Consequently one
could suggest that the exposures to nano-TiO2 or
nano-SiO2 may well be lower than the measurements
presented in Table 3 suggest. Uncertainty about the
origin and relative contribution of measured NP calls
for more elaborate sample analysis to quantify
exposure to ENPs.
The claimed highly agglomerated state of the SiO2
NP’s in the cement mortar used and the possible
contribution to the exposure of electrical equipmentgenerated NPs, are arguments for further physical/
chemical analysis of the samples. EDX/SEM analysis
might be a good option.
Notwithstanding the need for further analysis of
the NPs, comparing the 8 h-TWA exposure (Table 3)
with the proposed NRVs (Table 4) suggests that the
use of NRVs may provide a valuable tool for a first
workplace risk assessment. The calculated 8-h TWA
exposures to NPs (possibly as a mix of different types
of NPs) remain well below the proposed NRVs and to
date there is no indication that for the prevention of
adverse effects of the concerned nanoparticles the use
of a ceiling value is advisable. In view thereof no
further specific nano-risk related measures would be
necessary. However, given the observed exposure
pattern additional assessment of the peak exposures
seems appropriate (van Broekhuizen 2011). This
might lead to a 15 min-TWA and a short-term
peak exposure level should be leading in the risk
assessment and suggests the need for additional shortterm nano reference levels, for example in analogy
society on the improvement of energy management in
the context of climate change and the reduction of
greenhouse gasses does stimulate an increased market
share (Broekhuizen et al. 2009).
Risk avoidance is another drawback for use.
Potential users seem to wait with using nanomaterials, until more evidence for a safe use comes available.
Advocates for more openness of the industry about the
type of nanomaterials used in the products, have taken
up this point (IG DHS 2008; ETUC 2008; EEB 2009;
Broekhuizen and Reijnders 2010; FIEC, EFBWW
2009) and have suggested openness about health risks,
advice on how to use nanomaterials safely and
information about the so far unknowns. However, it
is questionable if voluntariness alone would suffice to
generate more openness in the communication. Voluntary initiatives to increase openness of industry
about their nanoproducts have been only limitedly
successful (Berger 2007; Helland et al. 2008; DEFRA
2008; Breggin et al. 2009; US EPA 2009), which in
some countries did lead to initiatives to develop legal
instruments to enforce more openness (e.g., The
Netherlands, France, Austria).
Measuring the personal exposure to ENP at
industrial workplaces is subject to several factors
which influence the level of NP exposure, as
presented here, and merit discussion. The first one
is the size range of the measured nanoparticles
concentration. The NanoTracer measures in the range
from 10 to 300 nm, meaning that in principle an overestimation of the amount of nanoparticles is possible.
For risk assessment this is not necessarily a problem
since there seems not to be a sharp limit for effects at
the 100 nm size, as is shown for example by Barnard
(2010) for TiO2 for the potential of generating of
ROS as a function of the nanoparticles size. Furthermore, the measurements show that the major part of
the measured particles is in the range \100 nm.
Especially the background concentration, the use
of electrical equipment, heaters, diesel aggregates,
and smoking are identified in this study as potential
confounding factors in ENP measurement. The use of
electrical equipment is of specific interest. This study
indicates that the use of electrical mixers and drilling
machines may contribute significantly to the workers
NP exposure. For instance, the difference measured
between drilling traditional and NanoCrete concrete
in the near field might relate to an emission of NPs
from the Nanocrete concrete, but it may also be that
73
___________________________________________________________________________________________
The awareness of majority of the end-users,
construction employers and employees about the
existence of nanoproducts and about their actual use
appears to be very low. It is concluded that communication about product performance and health risks
of nanomaterials has to be improved in the production chain.
Real-time exposure measurements in a limited
amount of exterior workplaces show a low 8 h-TWA
workers’ exposure to dispersed airborne NPs, if
compared with NRVs, but it is difficult to distinguish
ENPs from a NPs’ background exposure and from
NPs generated by the electrical machining equipment. Short-term peak exposures seem to be characteristic for the workplaces investigated. Further
chemical analysis of airborne workplace nanoparticulate samples is needed to elucidate the productrelated contribution to the measured nanoparticle
exposure. Comparison of the exposure with NRVs
shows a limited exposure, not exceeding the warning
level for 8 h-TWA exposures.
with the rule of thumb for a 15min chemicals’
exposure, used by Labour Inspectorates, NRV (15
min-TWA) = 2 9 NRV (8 h-TWA) and for peak
exposures NRV-peak = 10 9 NRV(8 h-TWA) (van
Broekhuizen 2011). For most of the cases presented
here, this would mean an exposure well below the
proposed NRV-peak and the 15min-TWA. Only for
the mortar mixing in situation 2 the NRV-peak might
be exceeded, which might lead to an advice to apply
risk mitigating measures during the adding actual
mixing of the NanoCrete.
Carbon nanotubes (CNT) were not found to be used
in the European construction industry. In the case that
this changes it is useful to point out that the suggested
NRV for CNT of 10.000 fibres/m3 (see Table 4) is
analogous to the established OEL for asbestos. It
should be mentioned that this asbestos OEL has
recently come under debate. The Dutch Health Council published an advice to lower the OEL for chrysotilic asbestos to 2,000 fibres/m3 and amphibolic
asbestos to 420 fibres/m3, in line with an acceptable
yearly fatality risk level of 4.10-5 (Dutch Health
Council 2010). One might argue that the levels
suggested by the Dutch Health Council should be
adopted in setting the level for nano reference value of
long CNTs for which the toxicity is not specifically
established, in line with findings that exposure to long
CNTs triggers responses that are similar to the effects
of asbestos (Poland et al. 2008a, b).
Acknowledgments The study was granted by the European
Commission, Directorate General Employment by the grant
agreement no. VS/2008/0500–SI2.512656 within the context of
the European Social Dialogue in the Construction Industry.
The authors like to thank the companies (construction
companies, raw material producers, product manufacturers,
waste processing), the industrial branch organisations, R&D
institutes and individuals for their valuable contributions to the
study, the insights provided and their openness in discussions.
The Stichting Arbouw, the Dutch bipartite expertise institute
for occupational health and safety in the construction industry,
granted the exposure measurements. The authors like to thank
Jan Uitzinger for help with the statistical analysis.
Conclusion
In 2009, the use of nanoproducts in the European
construction industry was at a relatively low level.
Within the as yet small nanomarket in the construction industry, primarily coatings and cement and
concrete dominate. The most important NPs in these
applications seem to be nano-TiO2 and silica-fume.
A major barrier is the high price of nanoproducts
used in bulk amounts, limiting the use to situations
where the customer specifically requests their use. A
higher use is foreseen for nanoproducts with energy
saving properties. Another barrier is the uncertainty
of potential manufacturers and end-users about
adverse occupational risks of ENPs leading to
reluctance in selecting these materials. The production of nanoproducts and their use is postponed until
more evidence comes available.
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Use of Nanomaterials in the Furniture Industry
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3.2
Useofnanomaterialsinthefurnitureindustry
R
egardingthemarketpenetrationofnanoͲenabledproductsand(unͲ)awarenessofcompanies
andworkers abouttheavailabilityandrisksofnanomaterialsthefurnitureindustryshows a
picture similar to that of the construction industry shown in the previous section (van
Broekhuizen 2012). The findings of van Broekhuizen (2012) dealing with information supply and
workplace exposure measurements are briefly summarized here. The limited downstream
information supply is explained by the finding that many companies in the sector keep the use of
nanomaterialsinproductsconfidential.Competitionandintellectualpropertyrightsarementioned
as reasons for confidentiality. Marketing also matters in this respect, but its impact on
confidentialityisambivalent:whileitholdsforsomecompaniesthat“nanotechnology”sells,itseems
to apply more generally that companies prefer not to label their product as “nano”. The onͲgoing
uncertaintyregardingthepotentialhealtheffectsofnanomaterialsisalsomentionedasareasonto
keep their use in products confidential, avoiding “unnecessary questions”. Another factor limiting
communication is ignorance. Upstream material suppliers themselves are often not well informed
andconsequentlycanprovideonlylittletonoinformationtothefurnituremanufacturer.
A large market potential for nanomaterials in furniture was identified, but in practice only a very
limiteduseofnanoͲenabledproductswasobserved.NanoͲSiO2wasusedinhospitalsandofficesin
easyͲtoͲclean, waterͲrepellent, oilͲrepellent and antiͲgraffiti coatings. NanoͲSiO2 is also applied in
high scratch resistant lacquers or in coatings to protect metal, wood or stone against erosion and
wear processes. It may protect wood against algal growth and attack by other organisms like
woodwormortermites.Furthermore,nanoͲSiO2isusedinconcretetoachieveanultraͲhighstrength
andhighdensitythatissuitableforuseinkitchenandstreetfurniture.NanoͲAgandnanoͲTiO2are
identifiedinbactericidalorselfͲcleaningcoatingsatthesurfaceoffurnitureinmedicalcentres,the
foodsector,swimmingpools,saunasandeveninevenpublictransportworksandvehicles.Nanoclay
was identified as stabilizer of pigments. NanoͲTiO2 nanoͲZnO and nanoͲCeO2 were found in use as
UVͲblocking agents, for example in wood protective coatings. Nanocellulose was identified as
compositematerialandnonͲwovenadsorbentwebs.
Limiting factors hampering the use of nanomaterials
are the still high prices, although lower price are
expectedwhenmarketvolumesgetlarge.Uncertainty
about adverse health effects remains an issue of
concern for manufacturers and may be a reason to
postpone their decision to apply MNMs in furniture
products.
Workplaceexposuremeasurements
x Workplace exposure measurements during high
pressure spraying of MNMͲcontaining lacquer on
woodpanelsinasprayͲcabinshowedhighnumber
concentrations in the exhaust air, but personal Figure1Highpressuresprayinginthespray
exposure concentrations far below the NRV8hrͲTWA cabin.Thearrowrepresentstheairflowofthe
ventilationsystem:greenindicateslownumber
(see in fig.1). The existing exhaust ventilation
ofnanoparticles;redindicateshighnumberof
systemprovedtobeeffectivealsoforMNMs.
nanoparticles.
77
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x LowͲpressure spraying of a MNMͲcoating on
furniture cushions using a manual pumpͲspray
andwipingcloths,inanotͲventilatedroomdid
notshowanyMNMexposure(seeFig.2).
x Sanding of wood panels treated with highly
scratchͲresistant lacquer, at an unͲventilated
workͲbench generated nanoparticles as a
fraction of the total sanding dust. The sanding
machine engine also released nanoparticles.
Wet sanding did not generate a measurable Figure2Coatingofadentistchaircushionusinga
MNMͲconcentration,butincaseoffullͲdaydry
lowͲpressurepumpͲsprayandasoftwiping
sanding and polishing workplace exposure
exceeded the NRV8hrͲTWA. It is likely that processͲgenerated nanoparticles contribute to this
numberbasedconcentration.
x During cutting of nylon textile treated with a waterͲrepellent coating with normal scissors no
nanoparticlesintheworkplaceaircouldbedetected.
In sum: in the furniture industry there is smallͲscale use nanomaterials. There is a large
information gap in the industry about nanomaterials and nanoͲenabled products regarding
availability,benefitsandpotentialrisks.Theidentifiedusesofnanomaterialsalwaysoccurredinthe
form of nanoͲenabled products. With the nanomaterials embedded in a liquid or solid matrix, the
exposuremonitoringfocusedonpracticeswheredustoraerosolsweregenerated.Thestudyshowed
that the existing exhaust ventilation, as installed for protection against “conventional” substances,
wasalsoeffectivetoprotectagainstexposuretonanoparticles.Theuseofelectricalequipmentmay
generatesignificantnumberconcentrationsofairbornenanoparticles.
3.3
Thepaintvaluechainandnanomaterials
an MaanenͲVernooij et al. (2012) have studied information about nanomaterials and
workplaceexposuretonanoparticlesintheDutchpaintvaluechain,whichincludescarrepair
materials.Theirresultsarebrieflysummarizedhere.
Interviewed downstream users in car repair shops are not triggered to obtain information about
nanomaterials,astheyfeelthatsuchinformationisnotimportant.Theyemphasizethatsafetydata
sheets (SDS) of products used do not report on nanomaterials. Neither the management, nor the
workersincarbodyrepairshopsknowwhethertheyareconfrontedwithcarsthatarecoatedwitha
nanoͲlacquerorwhethertheyusenanoproductsforrefinishing.Asaconsequencetheydon’tknow
whetherthereisariskforexposuretonanoparticles.Theinformationisneithersuppliedtothemby
thepaintmanufacturers,norbythesuppliersofthecars.Managementofcarrepairshopsdoesnot
have the chemical knowledge to demand upstream information from suppliers or manufacturers
aboutthecoatingcomposition(andespeciallyonthenanocontent).Itseemsthatmanypaintand
coatingmanufacturerskeeptheiruseofnanomaterialsincarrepairproductsconfidential.
Information supply about nanomaterials seems less of a problem amongst painting
contractors. The painting contractors organization FOSAG states that painting contractors are
inherentlyconservativeandscepticaltowardsinnovativeproductsandfearbusinessrisksandlosses
duealowerperformance.AbetterperformancehasyettobeprovenfornanoͲenabledpaints.The
branch itself does not experience ignorance, but it should be noted that nanoͲenabled paints are
V
78
The Paint Value Chain and Nanomaterials
___________________________________________________________________________________________
only applied when explicitly demanded by the customer (homeͲowner or architect). FOSAG stated
that it does not note anxiety about the possible health effects of nanoparticles among painting
contractors.
Workplaceexposuremeasurements
Analysingmomentsofpossibleoccupationalexposuretonanomaterialsalongthepaintvaluechain
shows that the risks of occupational exposure to primary MNMs mainly occur during paint
manufacturing.Thehighestprobabilityofexposurewasidentifiedwhenworkershandledrypowder
formraw(nano)materials.Theexposureprobabilityissignificantlyreducedwhenthenanoparticles
arehandledintheformofaliquidora(nonͲpowdery)solid.Inthatcasetheexposurecharacteristics
seemsimilartothatofhandlingormachiningacoatingwithoutanynanomaterial.
Personal sampling of airborne concentrations from nanomaterials emitted during paint production
(and corrected form the background) shows an arithmetic mean concentration for nanoͲTiO2 of
875,333 particles/cm3 (mean diameter 58nm) and for the additive SyloWhiteTM (an amorphous
sodium aluminum silicate that is not purchased as nanoͲcomponent) an arithmetic mean
concentration of 2,949,906 particles/cm3 (mean diameter 44nm). Taken into account the short
duration of the activities the exposure remains below the NRV8hrͲTWA (у0.5xNRV). However peak
exposuresexceedtheNRV15minͲTWAupto>12xNRV15minͲTWA.Measurementsinanotherpaintcompany
manufacturingapaintbasedonnanoͲTiO2showed8hrͲTWAexposuresfarbelowtheNRV8hrͲTWA.Van
MaanenͲVernooij et al. (2012) emphasize that the level of exposure is strongly influenced by the
handlingproceduresandthecontrolmeasuresappliedinaddingthebagstothemix.

In sum: the downstream information supply on nanomaterials’ release and potential risks
shows large gaps. Gaps may regard products (components) supplied to paint manufacturers and
professionalendusers,butmayalsoregardsinformationaboutproductssuppliedforservices(like
carrepairandmaintenance).Thelackofinformationisnotalwaysexperiencedasproblematic,asis
shownforpaintcontractors.Exposuretonanomaterialsinthepaintvaluechainisexpectedprimarily
duringpaintmanufacturing.Theexposuretoairbornenanomaterialsduringpaintmanufacturingis
stronglyinfluencedbythecontrolmeasuresandcaretakenduringthehandlingofthenanomaterials.
Exceeding of the NRV15minͲTWA is likely when insufficient control measures are taken. The source of
airbornenanomaterialsmayalsobe“conventional”drypowderingredients,whichcontainnanosized
particles. This source may dominate over the number concentrations generated by nanoͲ
components.
References
VanBroekhuizenF(2012),“NanoinFurniture”,StateoftheArt2012,ExecutiveSummary,IVAMUvABVMay
2012,EuropeanSocialDialogueintheFurnitureIndustry
VanMaanenͲVernooijB,LeFeberM,vanBroekhuizenF,vanBroekhuizenP(2012),Pilot“KennisdelenNanoin
deVerfketen”,TNOreportV9445|1,March2012.http://www.rijksoverheid.nl/documentenͲenͲ
publicaties/rapporten/2012/04/10/eindrapportͲpilotͲkennisdelenͲnanoͲinͲdeͲverfketen.html
79
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80
Chapter 4 Workplace exposure to nanoparticles and the
application of provisional nanoreference values in times
of uncertain risks Published in: Journal of Nanoparticle Research (2012) 14:770‐795
81
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82
Workplace Exposure to Nanoparticles
___________________________________________________________________________________________
Workplace exposure to nanoparticles and the application
of provisional nanoreference values in times of uncertain
risks
Pieter van Broekhuizen • Fleur van Broekhuizen
Ralf Cornelissen • Lucas Reijnders
•
Received: 17 July 2011 / Accepted: 6 February 2012
Springer Science+Business Media B.V. 2012
workplace air were up to several millions of nanoparticles/cm3. Conventional components in paint manufacturing like CaCO3 and talc may contain a substantial
amount of nanosized particulates giving rise to
airborne nanoparticle concentrations. It is argued that
risk assessments carried out for e.g. paint manufacturing processes using conventional non-nano components should take into account potential nanoparticle
emissions as well. The concentrations measured were
compared with particle-based NRVs and with massbased values that have also been proposed for workers
protection. It is concluded that NRVs can be used
for risk management for handling or processing of
nanomaterials at workplaces provided that the scope of
NRVs is not limited to ENPs only, but extended to the
exposure to process-generated NPs as well.
Abstract Nano reference values (NRVs) for occupational use of nanomaterials were tested as provisional substitute for Occupational Exposure Limits
(OELs). NRVs can be used as provisional limit values
until Health-Based OELs or derived no-effect levels
(DNEL) become available. NRVs were defined for 8 h
periods (time weighted average) and for short-term
exposure periods (15 min-time weighted average). To
assess the usefulness of these NRVs, airborne number
concentrations of nanoparticles (NPs) in the workplace
environment were measured during paint manufacturing, electroplating, light equipment manufacturing,
non-reflective glass production, production of pigment
concentrates and car refinishing. Activities monitored
were handling of solid engineered NPs (ENP), abrasion, spraying and heating during occupational use of
nanomaterials (containing ENPs) and machining
nanosurfaces. The measured concentrations are often
presumed to contain ENPs as well as process-generated NPs (PGNP). The PGNP are found to be a
significant source for potential exposure and cannot be
ignored in risk assessment. Levels of NPs identified in
Keywords Nanomaterial Nanoparticle Risk management Occupational Exposure Limit Nano reference value Health effects Exposure
measurement
P. van Broekhuizen (&) F. van Broekhuizen R. Cornelissen
IVAM UvA BV, Plantage Muidergracht 14,
1018TV Amsterdam, The Netherlands
e-mail: pvbroekhuizen@ivam.uva.nl
Introduction
Working with nanomaterials may result in exposure of
workers to nanoparticles (NPs) and the possibility that
adverse health effects develop (Borm et al. 2006;
Yokel and MacPhail 2011). A recent proposal of the
L. Reijnders
Institute for Biodiversity and Ecosystem Dynamics,
University of Amsterdam, Amsterdam, The Netherlands
83
___________________________________________________________________________________________
the way of application and the measures used to
mitigate exposure (Plitzko 2009; Brouwer 2010;
Wang et al. 2010; Lee et al. 2011; Vosburgh et al.
2011). Number-, mass-, and surface area exposure
concentrations have been suggested as metrics for
exposures to ENP (Abbott and Maynard 2010; Ramachandran et al. 2011). Heitbrink et al. have suggested
that for workplace exposure to NP the active surface
area concentrations can largely be explained by
particles smaller than 100 nm (Heitbrink et al.
2009). By assuming a spherical size for these nanoparticles the surface area can easily be related to the
number concentration (Ramachandran et al. 2011).
Brouwer et al. (2009) have offered a ‘decision logic’
as a guidance as regards how to proceed with the data
reporting and analysis. This is based on the statistical
difference of the average workplace concentration
during nano-activity periods compared to the background concentrations (near or far field), an elemental
characterization (using e.g. EDX) of the sampled ENP
and on observations during the measurements.
For risk assessment and –management, comparison
of measured exposures with acceptable or accepted
risk levels is essential. It has been questioned whether
the commonly used reference for substances, the
health-based recommended occupational exposure
limits (HBR-OEL) derived for ‘coarse’ particles
(typically [500 nm) are applicable for nanosized
particles (Schulte et al. 2010, Stone et al. 2010). As
yet no firm conclusion can be drawn which would be
applicable to all nanoparticles. Provided that the
chemical properties, as driver for the toxicological
behaviour, are the same for the bulk and the nanosized particles, then scaling-down might be an allowable methodology (Stone et al. 2010). Schulte argues
in favour of the derivation of nano-specific HBROELs motivated by the specific characteristics of the
nano-size. If different metrics are chosen for reporting
like particle surface area or number, he argues, it will
be necessary as well to make conversions to massbased on these metrics.
As yet no OELs have been derived for any
nanomaterial by the European SCOEL (the Scientific
Committee on Occupational Exposure Limits) or any
national OEL-setting authority. NIOSH has proposed
a recommended exposure limit (REL) for TiO2
nanoparticles in workplace air on the basis of available
toxicity data, specifically data linking tumours to
exposure (NIOSH 2011). This proposed standard is
European Commission defines nanomaterials as natural, incidental or manufactured material containing
particles, in an unbound state or as an aggregate or as
an agglomerate and where, for 50% or more of the
particles in the number size distribution, one or more
external dimensions are in the size range 1–100 nm
(EC 2011). This definition is clearly legislation/
registration oriented and not aimed to define nanomaterials in terms of risk. In the present publication
nanoparticles with a diameter up to 300 nm are
studied.
Workplace exposure to NPs may have three main
sources: engineered NP (ENP), process-generated NP
(PGNP) or incidental NP, which include enginegenerated NP (EGNP) and combustion-derived NP
(CDNP), and the environmental background NP. The
environmental background concentration originates
from natural sources (vulcanism, weathering, etc.) and
anthropogenic activities like combustion (Donaldson
et al. 2005; BéruBé et al. 2007; Evans et al. 2008). In
risk assessment of ENPs in occupational environments
identification of PGNP, distinguished from the background concentration is essential (Ramachandran et al.
2011). So far, measurements of workplace exposure to
ENP have been limited (Plitzko 2009, Brouwer 2010,
Wang et al. 2010, Lee et al. 2011, Vosburgh et al.
2011). From these measurements it appears that the
background concentration of NPs varies, and quite
often varies between 10,000 and 20,000 nanoparticles/
cm3 for industrial workplaces or offices in moderately
polluted city areas (Wehner et al. 2002).
EGNP present at workplaces may be generated for
example by electrical equipment like compressors,
universal motors, drilling machines, vacuum cleaners
and by diesel engines (Szymczak et al. 2007, van
Broekhuizen et al. 2011a, b). Measurements suggested
that workplace concentrations due to EGNP emissions
may exceed several 100,000 nanoparticles/cm3 up to
several million nanoparticles/cm3. The latter concentration seems to be almost up to a physical maximum
beyond which coagulation changes the concentration
rapidly as outlined by Kreyling (Kreyling et al. 2010).
PGNP have been reported in number concentration of
[1,000,000 nanoparticles/cm3 with a low mass concentration (\0.10 mg/m3) (Peters et al. 2006). Studies
done so far show that the actual exposure to engineered nanoparticles (ENP) may vary quite substantially depending on the physical status of the
nanomaterials (powder, paste, liquid), the process,
84
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0.3 mg/m3, as time-weighted average for up to 10 h
per day during a 40 h working week. This is a factor
16.6–33.3 stricter than the 5–10 mg/m3 private limit
values for fine TiO2 particles used in several European
Members States (SER 2012). NIOSH has also published a draft standard for exposure to carbon nanotubes and carbon nanofibers based on available
toxicity data (NIOSH 2010). In this case hazard would
justify an eight hours time-weighted average between
0.2 and 2 lg/m3 air, but due to a higher upper limit of
detection 7 lg/m3 was proposed.
Under the European directive REACH it is foreseen
that DNELs (derived no-effect levels) will be derived
by the manufacturing industry. DNELs are healthbased risk indicators and with REACH coming at age
it is expected that the amount of DNELs will rapidly
grow. To date, however, no DNELs have been derived
for nanomaterials, except from the draft DNELs that
were calculated as an exercise for MWCNT, fullerenes, nano-TiO-2 and nano-Ag by the ENRHES
project (Stone et al. 2010). Drawbacks for the rapid
development of DNELs are the cut-off values in
REACH for DNEL-derivation for substances brought
at the market in volumes of[10 tonnes/year/company
and the on-going discussions whether nanoparticulates
should be considered as different from their bulk form
for registration.
Pauluhn has proposed a generic mass-based approach
to estimate DNELs for manufactured nanomaterials
based on evidence from repeated rat inhalation exposure
studies suggesting that the particle displacement volume
is the most prominent unifying denominator linking the
pulmonary retained dose with toxicity (Pauluhn 2010).
He states that the experimental evidence obtained in the
most sensitive bioassay (rat) with granular biopersistent
particles supports the view that the prevention of
overload-like conditions may also prevent secondary
long-term effects to occur. He calculates a volumebased generic exposure of 0.54 ll PMresp/m3 9 q
(where, PMresp means respiratory particulate matter) to
represent a defensible OEL based on a combination of
generic theoretical considerations and empirical evidence. The mass-based limits can be calculated by
multiplication of the volume concentration with the
particles’ agglomerate density (q) (mass concentration
in mg/m3 = 0.54 ll PMresp/m3 9 q). In this article,
limit values as proposed by Pauluhn will be applied to
the workplace concentrations and compared with nano
reference values (see Table 4).
The EU Chemical Agents Directive (CAD)1 places
responsibility on employers to protect the health and
safety of workers from the risks from all chemical
agents, including nanomaterials. Central to this is the
employer’s risk assessment, to identify and use control
measures appropriate to the way the chemical agent is
used in their workplace. To achieve this, when OELs
or DNELs are lacking, the employers have the
obligation to derive safe exposure levels themselves,
even if existing knowledge gaps limit a reliable
derivation. This practice has led European and
national policymakers and industry representatives to
the belief that for nanomaterials a precautionary
approach should be applied. In such an approach the
REACH principle no data, no market was paraphrased
by in the principle no data, no exposure, where ‘data’
refers to hazard data (SER 2009; van Broekhuizen and
Reijnders 2011). The latter principle is clear about its
stated goal, but it has been recognised that its
consequence, a zero-exposure, is in practice unattainable. Therefore, the use of generic benchmark levels
was suggested, as a tool that can be used in risk
management of nanomaterials as long as health-based
limit values are not available (BSI 2007; IFA 2009).
Such benchmarks represent a warning level for
nanoparticles in the workplace atmosphere that should
lead to risk reducing measures when this level is
exceeded. BSI proposes a risk ranking system with a
mass-based approach for insoluble or poorly soluble
non-CMAR2 nanomaterials. A guidance value can be
derived by using a safety factor of 0.066 (15 times
lower) compared to the OEL of the bulk material. For
nanomaterials classified as CMAR in their bulk form a
general safety factor of 0.1 compared to the existing
OEL is suggested. IFA introduces a particle numberbased approach for recommended benchmark limits,
arguing that the size and density of the nanoparticles
must be employed as classification criteria for derivation of the recommended exposure limits. Based on
the IFA-methodology nano reference values (NRVs)
have been developed, as described in the following
1
The Chemical Agents Directive (CAD), are Council Directives on the protection of the health and safety of workers from
the risks related to chemical agents at work (98/24/EC), and on
the protection of workers from the risks related to exposure to
carcinogens and mutagens at work (2004/37/EC).
2
CMAR Carcinogenic, mutagenic, asthmagenic, reproduction
toxic.
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Table 1 Nano reference values, based on the benchmark levels as proposed by IFA and adapted according to discussions with IFA
and the Dutch expert panel
Description
Density
Benchmark
level (8-h
TWA)
Type NP
0.01 fibers/cm3
SWCNT or MWCNT or metal oxide fibres
for which asbestos-like effects are not
excluded
1
Rigid, biopersistent nanofibers for
which effects similar to those of
asbestos are not excluded
2
Biopersistent granular nanomaterial
in the range of 1–100 nm
[6.000 kg/m3
Ag, Au, CeO2, CoO, Fe, FexOy, La, Pb,
Sb2O5, SnO2
3
Biopersistent granular nanomaterial
\6.000 kg/m3
Al2O3, SiO2, TiN, TiO2, ZnO, nanoclay
Carbon black, C60, dendrimers, polystyrene
Nanofibers for which asbestos-like effects
are excluded
4
Non-biopersistent nanomaterial
Applicable OEL
reference values (provisional NRVs) for these benchmark levels (Dekkers and de Heer 2010), see Table 1.
The evaluation suggests that NRVs can be used as
pragmatic benchmark levels to reduce the workers’
exposure to nanomaterials and also suggests a few
adaptations to the IFA scheme. Based on the findings
in the current research project, the scheme for NRVs,
as presented in Table 1, was adopted in the Netherlands (van Broekhuizen et al. 2011b).
The NRVs, as presented here, are not health-based
in the sense that the values are not derived from
toxicological and epidemiological studies linking
doses of the substances to health effects. Still there
is a link with presumable health effects. An example is
the comparison of CNT-toxicity with asbestos-like
properties as shown in the results of Poland et al.
(2008). Underlying the NRVs is also the evidence that
the number of nanoparticles and the surface area (SA)
of the particles can be used as determinants for
possible health effects of low solubility particles
(Bermudez et al. 2004; Oberdorster et al. 2004; Abbott
and Maynard 2010; Aschberger and Christensen
2010). Because the number concentrations (or
the SA) can be better metrics for relating dose to the
observed effects of a specific nanomaterial, the
particles’ metrics preferred over the mass metric for
the NRVs. In using the nano reference values, a
number of choices have been made which are
explained in the following.
section of this article. NRVs are recognised by Dutch
authorities as an acceptable tool for precautionary
risk management (Dekkers and de Heer 2010; van
Broekhuizen et al. 2011b).
The aim of this study is to add to the measurements
of workplace exposure to NP and to test the usefulness
of the NRV concept as a tool for health & safety
management at the ‘nanoworkplace’ in settings as they
occur in practice. The following approach was chosen:
–
–
–
Fats, NaCl
Study the actual exposure to NP during the use of
nanomaterials in different occupational settings.
Assess the usefulness of NRVs as a health and
safety management tool for industrial settings.
Compare the approaches to worker protection of
Pauluhn (2010) and BSI (2007) with the application of the NRV-concept, as presented in this
article.
Nano reference values for risk management
The approaches for using benchmark levels as risk
management tool for nanoparticles as proposed by BSI
and IFA (BSI 2007; IFA 2009) was evaluated by the
Dutch expert panel on risks of nanomaterials and the
RIVM.3 The RIVM subscribes to the IFA approach as
a provisional alternative for HBR-OELs or DNELs
and advises to use the designation provisional nano-
•
3
Rijksinstituut voor Volksgezondheid en Milieu (National
Institute for Public Health and the Environment).
86
NRVs are developed for the risk management of
ENPs, but for practical risk management purposes
limitation of the scope of the NRVs only to ENP
___________________________________________________________________________________________
•
•
may complicate the measurements. As pointed out
in the introduction, process-related activities may
generate biopersistent nanoparticulates, which by
their nature are expected to exhibit hazardous
properties as well, comparable to those of ENPs.
Without further physical and/or chemical identification of the composition of the particles distinguishing between ENPs and PGNPs is not
possible. For risk management purposes it is
therefore suggested to apply a worst-case approach
and assess the airborne ENP combined with
PGNPs for situations where the NRV is not
exceeded. In cases where the NRV is exceeded
further characterisation of samples is indicated to
distinguish ENPs from PGNPs. This approach
simplifies the (interpretation of the) measurements
considerably and makes it possible to carry out
measurements with relative simple equipment and
without the necessity to go into extensive (and
expensive) physical/chemical analysis to analyse
the relative contributions of the sources. This
matter is further discussed in the discussion
section.
In the present study NPs are taken into account
with a diameter up to 300 nm. As argued by
Scenihr agglomerates/aggregates of nanoparticles
may have dimensions well beyond the 100 nm
size, which would not be considered to be nanoparticles, while retaining specific physicochemical
properties which are characteristic for nanomaterials most likely due to their relative large specific
surface area (Scenihr 2009). In addition, the
German Advisory Council on the Environment
advises a 300 nm limit for investigation and
monitoring, for precautionary reasons (SDU
2006). For this study the 300 nm limit was dictated
as well by the use of the measuring equipment, the
NanoTracer, which has this 300 nm as an upper
detection limit. This is further discussed in the
discussion section.
NRVs have by definition a provisional character
and they can be regarded as part of the current state
of the art of science. NRVs do not guarantee that
exposures below these values are safe. They are
pragmatic benchmark levels that have to be
accompanied by additional measures to minimize
exposure. Hence, in the Netherlands the use of
NRVs is primarily voluntary, but potentially
obligatory. If employers do not have alternative
•
•
scientifically acknowledged tools for exposure
assessment they are committed to use NRVs. As
such NRVs can be considered as ‘soft regulation’4
(Dorbeck-Jung 2011; van Broekhuizen and
Dorbeck-Jung 2012).
The NRV is established as a background-corrected, 8 h-TWA (Time Weighted Average) exposure level. As shown in the present study the
professional use of nanoproducts may show a
strongly varying emission of NPs, which often is
characterised by short peak exposure periods (van
Broekhuizen et al. 2011a). This indicates the need
for a practical tool to assess short term exposure
periods as well. Therefore, the assessment over
short exposure periods of 15 min-TWA seems
appropriate to serve as an additional tool for risk
management. For this a short-term NRV15min-TWA
was derived. This NRV15min-TWA can be derived
from the NRV8h-TWA, in analogy with the common
risk management approach of the Dutch Labour
Inspectorate for assessing short-term exposures to chemical substances (SDU 2006):
NRV15min-TWA = 2 9 NRV8h-TWA.
In addition, a Precaution Characterization Ratio
(PCR) was defined as the quotient of the measured
concentration of NPs and the NRV, in analogy
with the RCR (risk characterization ration) as
defined in REACH (ECHA 2008). The PCR is a
simple tool to signal whether the NRV is exceeded.
When the NRVs as indicated in Table 1 or the
exposure levels for short periods are exceeded the
source of the nanoparticles’ emission(s) should be
identified and possibilities to reduce the emission
of nanoparticles must be assessed.
Methodology
Particle concentrations of NPs emitted to the workplace air during occupational use of nanomaterials
were measured in eight different Dutch companies.
Six of them used ENPs. Control measurements were
4
By soft regulation we understand sustainable rules of conduct
which in principle have no legally binding force, but which
nevertheless have effects in regulatory practice to achieve
certain policy goals. Hard regulation refers to rules of conduct
that are based on legal authority. Soft regulation includes
standards, codes of conduct, and benchmarks etc. It can be
established by private and public organizations.
87
___________________________________________________________________________________________
nanomaterials. For non-fibre NPs a distinction
between the densities [6,000 and \6,000 kg/m3 has
to be made to distinguish category 2 and 3 substances
(see Table 1). Information about the biopersistence is
required to distinguish category 4 substances. When
pure MNMs are considered the information about the
density and biopersistence is provided in available
SDSs (safety data sheet). For PGNPs, which are not
further chemically characterized, in general an
assumption will have to be made that the emission of
the current process or activity is a mix of many
components. An expert guess has to be made for the
two parameters for the supposed dominant component
of the emission.Engine-generated and combustionderived NPs (generally metal oxides resp. soot type
products) can be classified as biopersistent substances
with a density \6,000 kg/m3, leading to a NRV of
40,000 particles/cm3. It is in general only the pure
metals that have a density [6,000 kg/m3.
The mass-based 8 h-TWA concentrations (as given
in Table 3) are calculated assuming that the particles
are a perfect sphere and that the density of the
nanoparticles during one activity equal.
The mean mass concentration for each specific
activity was estimated as
carried at two companies using only conventional nonENP products. The used measurement strategy complies with the methodologies described by Brouwer
et al. (2009), Ramachandran et al. (2011), but no
characterization of the chemical identity of NPs was
carried out. The measurement strategy fits in a tier 1
approach as defined in REACH, which is a reasonable
worst-case default scenario (ECHA 2008).
All particle concentration measurements are carried
out with an Aerasense NP monitor (NanoTracer): a
portable aerosol sampler of Philips Aerasense, Eindhoven, the Netherlands. The NanoTracer provides
real-time information about the number concentration
(particles per cm3), number-averaged particle diameter and surface area. The apparatus detects the
concentration of NPs in numbers of NP’s (nanoparticles/cm3) within a range of 10–300 nm, simultaneously with the mean particles diameter over a time
interval of 16 s or, in the fast mode, only the number of
NPs per cm3 over a time interval of 3 s. The technical
details of the Aerasense NP monitor are described by
Marra et al. (2010).
On board data logging capabilities were utilized for
the Aerasense NP monitor. A laptop computer with
software was used for both control and data acquisition
(NanoReporter 1.0.2.0, Philips Aerasense, Eindhoven,
the Netherlands) and data analysis (NanoReporter
1.0.2.0 and MS Excel, Microsoft Corporation, US). All
aerosol NP monitors used were time synchronized with
the laptop before commencement of sampling. Statistical analysis was carried out with the statistics
programme Stata.
Background concentrations were measured at the
workplace preceding the activities using nanomaterials. In most of the cases monitoring and source
emission measurements took place close to the
identified source of NPs with the NanoTracer in static
or in a hand-held position.
The evidence for the potential of exposure reflected
by the workplace air measurement studies is based on
the interpretation of time/activity concentration profiles. If an increment of concentration could be
associated with a task or an activity indicated the
presence of nano-sized objects, then it is interpreted
here in terms of ‘exposure’ to ENP, PGNP or a
combination of both.
The selection of a NRV requires knowledge about
the density and the biopersistency of the concerned
CM ¼ c
n
qX
d 3 CP;i
n i¼1 i
ð1Þ
where C M is the mean mass concentration (mg/m3) of
the measured airborne nanoparticles for the specific
activity,c is a constant: p6 1015 ; di is the measured (16
second saverage) particle’ diameter (nm) of the
measured nanoparticles, q is the density of the
measured particles (kg/m3), CP;i is the measured
background-corrected particles’ concentration of the
nanoparticles CP;i ¼ Ni ðcm3 Þ ; and n is the number of measurements per specific activity.
The PCR8h-TWAwas estimated as
PCR8hTWA ¼
n
t 1 X
CP;i
8h n i¼1 NRVi
ð2Þ
where t is the time the component is used (or activity is
carried out) and NRVi the NRV for the component.CP;i
is the measured background-corrected particles’ con
centration of the nanoparticles CP;i ¼ Ni ðcm3 Þ ;
and n is the total number of measurements.
88
___________________________________________________________________________________________
speculated by the authors that for black passivation
nano-silica or nano-alumina is used. For blue passivation the Material Safety Data Sheet (MSDS) mentions
a component with a valency of 3, presumably Cr3?(III),
which may oxidise in the bath to Cr(VI). The nanocomponent, supplied as a concentrated suspension, is
used in an electroplating dipping bath (size ca. 1 9 3 m,
2 m depth) at room temperature. Measurements were
carried out above the dipping bath at a distance of
approximately 1 m of the fluid surface. In addition, tests
were carried out to find out whether NPs are generated
during abrasion of the finished surface. For abrasion a
table-top rotary platform abraser was used with nonplated metal, metal plated with non-nano material and
metal plated with nanomaterial (blue passivation). Static
measurements were carried out at a distance of 10 cm
from the abraser.
The PCR15min-TWAwas estimated as:
PCR15 min TWA ¼
t
1
15 min n
n
X
i¼1
CP;i
2 NRVi
ð3Þ
For a 15 min short-term exposure period activities
were selected for periods with a peak concentration of
at least CP,peak [3*CBC and CP,peak [2* CP,median,
where CBC is the average background concentration
(arithmetic mean).
In these calculations, errors can be made in the
selection of the particles’ density and the correction of
the background. For specific components, which are
considered to be monodisperse system, and for the
average particles’ density of PGNPs it is likely that in
worst-case estimations an error can be made of at least
50%. For correction of the measurements for the
(fluctuating) background the average background
concentration was used. This as well may introduce
an error in the calculations.
The BSI benchmark was calculated based on the
OEL, as given in the SER-database (SER 2011) for the
coarse material as OEL/15 for the nanoscale particles,
supposing a non-CMRS nature of the components
(CMRS carcinogenic, mutagenic, reproduction toxic,
sensitizing). For non-characterized material (PGNP)
the OEL of 5 mg/m3for respiratory dust was used. For
soot an OEL was selected equivalent to the OEL for
diesel exhaust fumes. The nano-TiO2 OEL was based
on the recently advised REL (NIOSH 2011).
Calculation of the Pauluhn-DNEL was based a
volume-based generic mass concentration with the
following algorithm: DNELPauluhn = 0.5 ll nanoparticles/m3 9 q, where q is the density of the nanoparticles in kg/m3. The selection of q was identical as
indicated for the NRVs. The BSI and the Pauluhn
approach both are described for MNMs, but for
comparison reasons their methodology was applied
as well for PGNPs.
Nanopaint manufacturing
The paint manufacturing company produces batches
of waterbased nano-paints a few times per year. Solid
(powdery) additives, coarse TiO2, CaCO3, talc and
nano-TiO2 are supplied in paper or plastic bags. After
cutting them open with a Stanley knife the bags are
shaken out manually in the agitator vessel. The vessel
is constructed with exhaust ventilation. Personal
monitoring measurements were carried out with a
NanoTracer attached to the belt of worker. The
background was determined at the production location
preceding the manufacturing of the batch. A second
NanoTracer was used to measure the emission of the
nanoparticles in the near field at a distance of
approximately 1 m.
Manufacturing pigment concentrates for plastics
manufacturing
The company manufactures nano-ZnO concentrates
for plastics applications. Measurements were carried
out during the manufacturing of a pilot batch, in an as
yet not-optimized production plant. A dispersing agent
(solid) is added to a melted mineral wax in a mixing
vessel, heated up to 160C, after which solid nanoZnO powder is mixed in the wax. Both components
were supplied in a 20 kg storage vessel. Six vessels
with nano-ZnO were added. The solid powders are
transferred from the storage vessel to the mixing
vessel by vacuum transfer with an aspiration lance into
Description of the workplaces and measurements
Electroplating plant
In electroplating, nano-components are used as a
substitute for the carcinogenic Cr6?(VI) to improve
scratch resistance and corrosion stability of the passivation coatings. The exact type of the nanoparticles used
is kept confidential by the supplier of material. It is
89
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coating is further handled in a variety of production
steps to generate a finished product. These finishing
steps require several mechanical polishing steps and
steps with high temperature gas heating. Measurements
of the emission of NPs (in this case called ultrafine
particles-UFP) were also carried out near the equipment
present in the plant. The background NP-concentration
was determined in the room where the Al2O-3- was
dispersed, preceding the dispersion operation.
the mixing system. The dispersion is vigorously mixed
with an internal circulating pump system and an
external mixer. Local exhaust ventilation was applied
above the mixing vessel. The mixing vessel itself was
covered with a provisional cover, not completely
closing the vessel. A small opening was left around the
entrance of the external mixer. Static measurements
were carried out with a NanoTracer above the
provisionally closed vessel at a distance of approximately 10 cm from the top of the vessel (ca. 50 cm
from the liquid surface). Measurements were also
carried out near the storage vessel during the vacuum
up of the ZnO at 1 m distance. A second batch was
made in the afternoon with the same procedure, but
with more care taken to prevent emissions by more
thoroughly covering the small remaining openings of
the mixing vessel with cardboard.
Car refinishing
In car refinishing, abrasion and spraying operations are
carried out, using a nano-TiO2 coating and a 2-component nanocoating (with unknown nanomaterials).
During both types of activities nano-coatings were
tested and compared with otherwise similar conventional coatings. For abrasion activities exhaust ventilated equipment and wall exhaust ventilation are
commonly used. During the exposure measurement
ventilation was switched off, to avoid confounding
data by the possible (unknown, uncontrollable) emission of ventilation engine-generated NPs. The abrasion apparatus was air-pressure driven (not electrical)
and equipped with an eccentric rotor blade with a
5 mm offset. Abrasion was carried out with T-Euro
747 Velcro discs with a P400 grit made of anti
clogging aluminium oxide material, except for the
conventional Mercedes coating that was abraded with
a more coarse P80 grit. The P400 grit is commonly
used in car refinishing. During spraying of the coating
in a closed spraying cabin, normal floor-ventilation
was used with an airflow velocity of 0.2 m/s and a
capacity of 26,000 m3/h. The spraying pistol used was
a Devilbiss (air-pressure driven) and was operated as
specified by the supplier of each coating. Personal
exposure measurements were carried out with a
NanoTracer in the breathing area near the HEPAfilter equipped breathing mask that was used for
personal protection. Nitril gloves and protective
clothing were worn.
Production non-reflective glass
The principle of the non-reflective glass is based on the
creation of a transitional layer on glass with an
intermediate refractive index (in-between glass and
air), resulting in a strong reduction of light reflection.
For this, a polymer suspension containing nanomaterials is applied to sheets of glass. This suspension is
made at a different location. The layer is applied by
dipping of the glass in the polymer suspension
followed by a heating step in an enclosed room.
Subsequently, the sheets of glass are cut and packed
for transport. Coating and heating are automated
processes in a closed space in the production hall. Dry
coated sheets of glass are further handled manually.
Emissions of ENP might be expected during the
cutting of the glass, and during waste management: the
breaking of glass, which is not up to specification.
The cutting and breaking activities were monitored.
Manufacturing fluorescent tubes
For manufacturing of fluorescent tubes different nanosized metal-containing pigments are used. The focus
was on the production of a nano-Al2O3 dispersion used
for the inside coating of glass tubes. To this, solid nanoAl2O3 powder (with a primary particle size of 13 nm) is
supplied in paper bags and transferred to the mixing
vessel by vacuuming them up with an aspiration lance
into the mixing system. This work is done in a small
room having a wall with exhaust ventilation. The
Manufacturing ‘conventional’ non-nano alkyd
wall paint
To control the emission of NPs from ‘non-nano’ paint
component measurements were carried out during the
production of a ‘conventional’ solvent-based white
alkyd matt wall paint. The following solid components
90
___________________________________________________________________________________________
(supplied in paper bags of *1.0 9 0.490.2 m) were
added to the mix: an amide wax (1 bag), a clay mineral
(1 bag), talc (10 bags), CaCO3 (16 bags) and (coarse)
TiO2 (18 bags). The bags were cut open with a Stanley
knife and shaken out manually in the agitator vessel
through the rectangular chute with upright edges
(*1 m 9 30 cm) that was made in the well-closed
cover of the agitator vessel. Measurements were
carried out manually with a NanoTracer above the
vessel at a distance of *30 cm from the chute. The
background concentration of NPs was determined at
the production location preceding the manufacturing
of the batch.
bathes containing nano and non-nano materials. The
blue passivation nano-bath gives rise to a slightly
higher concentration than the non-nano bath, with
average nanoparticle diameters being above 100 nm.
Because nanomaterials used in the passivation bath are
non-volatile it might be that the engines used in the
electroplating process generate the observed particles.
Averaged over the 8 h working day, for a worker
working the whole day in this area a personal exposure
would exceed a NRV of 40,000 particles/cm3, assuming a density \6000 kg/m3, reflecting a low metal
content. For the activities with the rotary platform
abraser a NRV of 20,000 particles/cm3 is used,
reflecting an emission with a high metal content. The
results are graphically presented in Fig. 1 in a plot
with the number of NPs versus the average NPdiameter.
The average diameter of the NPs generated during
abrasion is the smallest for the abraded coated objects
(nano and non-nano), larger for the uncoated metal
and the largest for the free running abraser. The fact
that both the coated nano and the coated non-nano
abraded metal plates show a rather similar emission of
NPs with a similar average diameter suggests that the
generation of particles in this process is not nanomaterial-specific. Table 3 shows a PCR15min-TWA [1 for
the three abrasion activities, with and without coating.
This suggests the generation of nanoparticles during
abrasion, presumably being a mix of metal particles
and coating particles.
Test long-term wear lubrication in metal company
The possible emission of PGNPs from operating
electrical engines was controlled at a company
involved in testing long-term wearing of bearing
systems. Measurements were carried out with large
‘heavy’ machines and with smaller ‘light’ table-top
machines. 11 heavy machines (type Asea MBL132 SB
38.2with a speed of 2,580 rpm, a load of 16 kW and
lubricated with turbine oil) carried out 2-months
duration tests. 14 light machines (type HXUR 365 G
2 B 3, operating at a variable speed, temperature and
load) carried out measurements with different type of
lubricating oils (Shell Turbo T9, Turbo T32, Turbo
T68, and Turbo T100). No permanent work was
carried out near the running machines. Static measurements were carried out located in-between the
machines, at a distance of 10–20 cm from the nearest
machine. The background was determined in the
operating room, next to the halls with the machines,
because measuring the background in the same area
was not possible due to possibly confounding PGNPs
generated by the continuously running machines
(which were actually tested).
Nano-paint manufacturing
No emission of NPs linked to handling nano-TiO2
during the manufacturing of a white water based nanowall paint was observed (Fig. 2, period M). A small
emission of NPs is observed during the addition of
conventional ‘coarse’ TiO2 (period K). Emission of
NPs is also observed during the addition of the
additives (period G) and of CaCO3 (period R). This
might hold as well for talc (period S), as suggested by
the results of the measurements in the near field (see
Fig. 3). The personal measurements could not be
conclusive for talc because the NanoTracer used for
personal monitoring appeared not to function at the
moment of the addition of talc.
Based on their chemical identity all components are
assigned a NRV of 40,000 nanoparticles/cm3. Regarding the observation of the handling of the different
Results
The results of the measurements are summarized in
Table 2.
For the electroplating plant the results show an
elevated level of NPs in the air above both, passivation
91
12.9
1.9
3.6
2.4
H, Laboratory, background
I, Rotary abraser, free running motor
J, Rotary abraser, metal uncoated
K, Rotary abraser, metal electroschel nano
M, Rotary abraser, metal coated non-nano
0
0
13.7
10.8
K—Adding bulk TiO2
M—Adding nano-TiO2
92
0
111.6
16,065
8.4
109.7
11.0
20.0
8.6
23.3
B 1—Dispersing agent
C 1—Mixing nano-ZnO
D 1—Storage vessel
O2—Background
B2—Dispersing agent
3.2
13.5
5.8
Dumping waste glass
Glass cutting 1
Glass cutting 2
11.2
3.9
3.6
D—Background
E—adding nano-Al2O3
H—Wiping machine
22.1
Background
Production of non-reflective glass
C2—Mixing nano-ZnO
0
30.9
A 1—Pre-heating wax
0
0
13,695
0
0
0
10,528
7,335
44,992
19,027
14,767
0
18.1
O 1—Background
5,025
0
11.5
Near field (average full batch)
R—Adding CaCO3
0
13.0
G—Adding solid components
0
63.8
111.6
Full period batch manufacturing
7,320
52,884
74,949
46,355
9,470
0
31,013
0
10,332
13,103
233,854
0
18,383
0
0
0
12,671
27,855
5,888
13,230
73,916
178,711
61,567
0
5,516
0
0
0
8,220
0
0
19,451
63,427
89,011
57,261
21,771
1,276
46,222
27,929
14,020
242,955
0
23,940
0
0
0
13,159
45,888
9,128
14,370
79,282
726,480
112,987
3,907
5,873
0
3,345
1,845
25,140
3,585
1,193
21,030
79,475
94,004
62,806
25,820
2,674
55,392
38,218
276,266
2,258
39,499
0
0
2,156
13,897
99,907
48,289
15,570
106,196
1,157,242
242,347
10,781
6,623
0
29,723
3,765
47,955
18,420
7,215
22,898
105,221
100,152
68,228
28,107
6,372
78,324
49,142
15,324
p75
Max
Mean
19,005
2,649,870
39,975
64,770
11
0
10,029
35,126
517,275
143,640
22,770
158,587
6,226,237
1,345,177
32,347
9,855
25,703
244,485
61,200
128,895
40,095
270,135
82,230
115,009
110,034
72,357
60,844
11,350
121,021
55,394
14,323
436,997
1,509
28,875
0
0
603
13,391
70,148
32,521
14,364
89,999
1,077,011
216,784
6,029
6,217
1,039
39,043
1,495
33,234
11,573
13,212
21,613
82,765
93,933
61,308
25,937
3,747
64,630
34,090
80
20
27
27
42
24
61
116
21
22
41
44
25
27
23
24
22
28
39
40
52
66
80
106
111
27
32
33
130
95
83
150
36
39
59
58
44
39
33
30
38
40
42
42
55
74
92
106
114
94
p25
Min
Med
Min
p25
Diameter (nm)a
Particles per cm3
F—Background
Manufacturing nano-wall paint
3.9
15.7
D, Blue passivating bath, nano
13.2
10.2
C, Passivating bath, non-nano
Sampling time (min)
B, Electroplating hall, bath background
Event
Table 2 Background-corrected number of nanoparticles and their average diameter at different locations
28
35
40
130
117
90
177
57
54
74
71
77
43
43
38
42
42
45
42
57
79
104
109
117
99
Med
29
37
47
130
131
100
204
88
73
82
81
115
44
51
49
47
48
47
46
61
83
110
114
119
102
p75
232
43
57
279
239
188
286
236
152
135
95
241
89
272
138
272
149
48
50
64
93
120
119
125
116
Max
42
35
40
130
113
95
183
68
64
72
70
100
46
56
45
46
45
44
44
58
79
101
110
117
98
Mean
___________________________________________________________________________________________
1.6
4.4
2.3
1.2
4.4
Q—Sealing machine, (Hall AB)
U—Melting (Hall B)
W—Pumping machine (Hall B)
Y—Polishing product
AA—Coating and drying
93
H—TiO-2 (pigment) (solid)
19.2
24.0
Heavy machines, hall a
Light machines hall b
0
15.2
3.2
11.6
7.1
E—Abrasion plastic bumper R
G—Abrasion nano-TiO2 coating
H—Abrasion 2-component nano coating
10.5
P—Spraying conventional coating
Max
Mean
0
0
0
0
689
0
0
0
4,928
513
3,186
6,980
5,387
5,805
0
8,683
7,166
25,718
270,957
55,300
9,971
7,245
9,323
9,075
15,088
0
272,619
228,868
303,765
298,568
495,804
117,473
400,264
0
22,100
0
6,905
2,592
5,009
16,173
16,767
7,047
0
21,316
8,025
34,275
553,201
132,000
30,278
9,285
10,755
9,765
19,217
0
317,102
280,661
311,370
306,135
1,789,889
123,912
1,738,635
5,474
60,429
12,631
8,978
6,872
6,669
26,568
28,553
9,896
223
28,715
9,071
51,803
1,151,704
576,251
51,210
19,099
17,993
10,594
22,403
113,191
401,265
568,855
317,520
311,618
2,158,520
128,962
5,803,324
303,764
251,033
159,665
33,440
12,299
54,594
75,222
93,488
29,903
2,255
63,380
47,220
118,005
1,418,580
3,106,170
54,180
32,205
3,106,170
15,840
266,664
338,864
533,935
621,475
323,850
322,845
2,833,189
136,294
11,044,905
21,207
56,968
15,820
7,681
4,116
7,082
19,492
20,827
8,206
a
Empty cells indicate that the measurement was carried in fast mode of the NanoTracer and no diameters were monitored
0
21,934
8,545
44,239
690,983
569,729
30,904
14,155
67,954
9,871
31,089
61,555
344,622
357,594
310,918
305,687
1,535,578
122,788
3,243,690
Min lowest measured value, p25 25% percentile, Med Median value, p75 75% percentile, Max highest measured valued, Mean Arithmetic mean
The events are shortly explained in the ‘‘Methodology’’ section
12.4
N—Spraying 2-component nano coating
L—Spraying nano-TiO2
0
12.6
C—Abrasion conventional coating R
0
14.5
11.0
A—Abrasion conventional coating M
2,552
0
0
5,085
Average background
Vehicle refinishing
34.2
Background
Long-term wear lubrication
8,880
10,410
15,270
5.5
F—Talc (solid)
3.2
0.8
C—Clay mineral (solid)
5,220
5,205
5,220
0
0
213,067
126,027
296,595
290,460
127,353
108,250
301,770
70,575
1.5
B—Amide wax (solid)
p75
20
24
22
42
54
31
30
33
37
89
42
48
32
24
19
25
21
19
41
19
77
35
46
72
59
76
50
53
97
106
132
124
50
34
21
27
29
50
53
19
p25
Min
Med
Min
p25
Diameter (nm)a
Particles per cm3
3.9
89.0
Batch manufacturing
G—CaCO3 (solid)
37.2
Background
Manufacturing non-nano alkyd paint
3.6
1.8
P—Wiping unit (Hall AB)
1.1
N—Hall AB
2.4
L—Hall AB Hor A1
Sampling time (min)
I—Adjusting device
Event
Table 2 continued
112
69
127
83
88
86
63
60
115
112
114
139
70
42
26
41
57
56
57
21
Med
138
113
170
93
126
101
85
128
140
121
158
157
80
59
53
56
70
63
62
26
p75
266
252
274
186
269
212
150
255
289
157
272
243
135
129
89
63
90
135
97
35
Max
112
81
120
87
104
90
71
86
122
114
121
144
72
52
38
42
53
58
59
23
Mean
___________________________________________________________________________________________
___________________________________________________________________________________________
Fig. 1 Double boxplot electroplating plant, background-corrected average number of nanoparticles/cm3 versus average
particle diameter. Vertical line boxplot number of particles/cm3,
minimum, p25, median, p75 and maximum. Horizontal dotted
line average diameter, minimum, median and maximum
bags, it is highly suggestive that the measured peaks
consist of NPs of the component that was added at that
moment. For the full period batch manufacturing the
PCR8h-TWAwas \1 (see Table 3).
It is likely that a rapid dilution of NPs in the
workplace air takes place (Fig. 3, near field measurements). The emission of NPs from talc (which was
omitted in the personal exposure measurement) is
clearly traceable (period S). Apparently the local
exhaust ventilation cannot prevent the emission of
small amounts of talc into the workplace air.
short-term exposure, especially for the adding of the
talc and CaCO3, the advised short-term levels are
exceeded: PCR15min-TWA [1 (see Table 3).
The manufacturing of the pigment concentrates concerns principally three steps: heating the wax, adding a
dispersing agent and adding the nano-pigment, both
with an aspiration lance under vigorously stirring. For
batch 1 the generation of NPs in the workplace air is
graphically represented in Fig. 5.
A large emission of NPs is observed during the
adding of the nano-ZnO. Emission of NPs near the
storage vessel is lower. Better coverage of the mixing
vessel in batch 2 results in a strong reduction of the
emission of NPs.
Figures 6 (batch 1) and 7 (batch 2) show the number
of NPs/cm3 versus their diameter. Batch 1 shows that
NPs emitting after adding of the dispersing agent and
the nano-ZnO have an almost comparable average
median particle diameter of around 55 nm, which is a
little lower than the average median NP size measured
during the heating of the wax and during the background measurement (74 nm). The average particle
diameter of NPs sampled near the storage vessel is
Manufacturing non-nanopaint
Figure 4 shows measured nanoparticle concentrations
during the production of a conventional paint. High
NP emissions of CaCO3 (period G) and talc (period F)
are observed. Also for conventional (‘coarse’) TiO2 a
slight emission of NPs might be observed (period H).
All components are assigned a NRV of 40,000
nanoparticles/cm3. When it is assumed that the
workers manufacture one batch per day the 8h-TWA
concentration remains well below the NRV
(PCR 8h-TWA \1). When these activities would be
carried out more than three times a day under the same
conditions, the PCR8h-TWA might be exceeded. For
94
1,396
3,606
5,645
4,947
I—Rotary abraser, motor
J—Rotary abraser, metal uncoated
K—Rotary abraser, metal electroschel nano
M—Rotary abraser, metal coated non-nano
95
a
a
a
a
52,792
842
4,100
18,478
Full production process 1
C2—Dispersing ZnO in mixing vessel
40,000
Glass cutting 2
40,000
3,238,755
117,853
1,530,643
L—Hall AB Hor A1
N—Hall AB
40,000
40,000
40,000
40,000
432,062
E—adding nano-Al2O3
H—Wiping machine
40,000
40,000
40,000
40,000
40,000
Glass cutting 1
Dumping waste glass
2
40,000
245,989
C1—Dispersing ZnO in mixing vessel
Full production process 2
40,000
3,810
40,000
366
40,000
40,000
40,000
40,000
40,000
40,000
20,000
20,000
20,000
20,000
40,000
38.27
2.95
80.97
10.80
a
0.00
0.00
0.46
0.03
0.03
1.32
5
0.1
0.01
a
a
a
a
0.02
0.25
0.28
0.18
0.07
1.61
0.83
8 hTWA
NP/cm3
40,000
PCR
NRV
A1—pre-heating wax
R—Adding CaCO3
M—Adding nano-TiO2
K—Adding bulk TiO2
G—Adding solid components
969
64,327
D—Blue passivating bath, nano
33,249
8 h-TWA
BC
NP/cm3
C—Passivating bath, non-nano
Electroplating industry
Activity
20
1.47
50
5.26
0.00
b
b
0.03
0.08
0.08
0.01
100
100
1.67
0.3
0.7
0.37
0.66
0.37
2.44
2.7
1.89
1
b
b
15 minTWA
Soot
Soot
Soot
Soot
Al2O3 bulk
No emission
No emission
SiO2 (amorph)
Mix
ZnO
Non-ionic
Mix
ZnO
Non-ionic
Paraffin wax
CaCO3
TiO2
TiO2
Bentone
Average
Guess
Zn
Fe
Cu
Organic aerosol
Organic aerosol
Dominating
component(c)
Table 3 Comparison of background-corrected 8 h-TWA concentrations with NRV and mass-based concentrations
2,000
2,000
2,000
2,000
4,000
2,000
2,000
2,000
3,000
5,610
800
3,000
5,610
800
800
2,710
4,240
4,240
1,470
3,000
7,000
7,133
7,860
8,950
2,000
2,000
kg/m3
Density
0.0433
0.0033
0.0271
0.0068
0.0002
0.0000
0.0000
0.0000
0.6018
0.0104
0.6683
0.0202
0.0006
0.0024
0.0005
0.0032
0.0004
0.0020
0.0240
0.0280
0.0449
0.1123
0.0880
0.0545
Average conc.
activity BC
mg/m3
0,0433
0,0033
0,0271
0,0068
0.0000
Full day
0.0000
0.0000
0.0000
0.5 h/day
0.2707
0.0292
0.0002
0.4128
0.1527
0.0004
0.4128
3 h/day
a
a
a
a
0.0004
1 batch/day
0.0015
0.0018
0.0028
0.0070
0.5 h/day
0.0880
0.0545
Full day
8 h-TWA BC normal
working day
mg/m3
___________________________________________________________________________________________
56,620
96
0
Light machines hall b
28,324
10,020
N—Spraying 2-component nano coating
P—Spraying conventional coating
40,000
40,000
40,000
40,000
40,000
40,000
40,000
40,000
40,000
40,000
40,000
40,000
40,000
40,000
40,000
40,000
40,000
40,000
40,000
7.52
0.25
0.71
0.17
0.09
0.05
0.01
0.21
0.22
0.00
0.55
a
a
a
a
a
0.27
1.42
8.49
8.82
7.65
0.24
0.64
0.12
0.14
0.03
0.18
0.28
0.26
0.00
0.27
0.09
2.22
2.56
0.01
0.01
2.56
0.71
4.17
4.35
3.85
3.7
15 minTWA
Guess
Guess
TiO2
Guess
TiO2
Polymer
Polymer
Polymer
No emission
Soot
TiO2
CaCO3
Talc
Bentone
Amide wax
Average
Soot
Soot
Soot
Soot
Soot
Dominating
component(c)
2,000
2,000
4,240
2,000
4,240
2,000
2,000
2,000
2,000
4,240
2,710
1,050
1,470
800
3,000
2,000
2,000
2,000
2,000
2,000
kg/m3
Density
0.0011
0.0029
0.0012
0.0026
0.0089
0.0021
0.0033
0.0047
0.0000
0.0002
0.0201
0.1720
0.0085
0.0003
0.0000
0.0064
0.0018
0.0096
0.0100
0.0066
0.0067
Average conc.
activity BC
mg/m3
0.0005
0.0015
0.0006
0.0013
0.0044
0.0010
0.0017
0.0023
4 h/day
0.0000
0.0002
Full day
a
a
a
a
a
0.0024
2 batch/day
0,0018
0,0096
0,0100
0,0066
0,0067
8 h-TWA BC normal
working day
mg/m3
d
c
b
a
min-TWA
was calculated
For calculating the 8-h TWA concentration for vehicle-refinishing activities it was assumed that the different activities lasted the full day
The selected compound is an expert guess based on the current process
No 15 min short-term peaks are identified during this process
For short-period activities (2–15 min) calculation of an 8 h-TWA is not realistic, so only the PCR15
BC Background corrected
The comparison is expressed in the PCR8h-TWA and the PCR 15min-TWA. Bold values represent situations where PCR8h-TWA or PCR15min-TWA are [1. The mass concentration was calculated
as described in the ‘‘Methodology’’ section. The last column shows the 8 h-TWA mass concentrations assuming a time period for the actual process
3,656
1,846
6,989
303
8,245
C—Abrasion conventional coating R
H—Abrasion 2-component nano coating
8,907
A—Abrasion conventional coating M
Vehicle refinishing(d)
21,933
a
a
a
a
a
H—TiO2 (pigment) (solid)
G—CaCO3 (solid)
F—Talc (solid)
C—Clay mineral (solid)
B—Amide wax (solid)
10,778
339,687
352,659
40,000
40,000
300,752
305,983
8 hTWA
NP/cm3
PCR
NRV
8 h-TWA
BC
NP/cm3
Q—Sealing machine, (Hall AB)
Activity
Table 3 continued
___________________________________________________________________________________________
___________________________________________________________________________________________
Fig. 2 Personal measurement of nanoparticle concentration
during adding solid components to a waterborne nano-wall
paint. A background, G addition of solid additives, K addition of
coarse TiO2, M addition of nano-TiO2, R addition of CaCO3.
Solid components are added manually by pouring the content of
paper and plastic bags into the agitator vessel
Fig. 3 Measurement of nanoparticle concentration in the near
field during adding solid components to a waterborne nano-wall
paint. Solid components are added manually by pouring the
content of paper and plastic bags into the agitator. Sampling
took place manually at a distance of 1 m from the agitator
vessel. G addition of solid additives, K addition of coarse TiO2,
M addition of nano-TiO2, R addition of CaCO3, S addition of talc
considerably larger (177 nm). The real-time measurement (Fig. 5) shows a sharp increase of the emission
directly after dosing the dispersing agent and the nanoZnO suggesting the peaks to reflect nanoparticulate
mixtures of wax and/or dispersing agent and/or nanoZnO. This suggestion might be supported by the
observation of the larger average particles’ diameters
sampled in batch 2 (Fig. 7), which may be explained by
assuming that larger wax agglomerates have been
formed. The larger average particles’ diameter of the
sampled airborne NPs in the air near the storage vessel
may be agglomerates of nano-ZnO particles. The
information supplied by the company is that the
primary particle diameter of the nano-ZnO is 40 nm.
97
___________________________________________________________________________________________
Fig. 4 Measurement of nanoparticle concentration during
production of ‘conventional’ solvent borne white alkyd paint.
The y-axis uses a logarithmic scale. Solid components are added
manually by pouring the content of paper bags into the agitator.
B amide wax, C clay mineral; F talc, G CaCO3, H TiO2.
Sampling took place manually at a distance of 30 cm from the
adding of the solid powders
Fig. 5 Measurement of nanoparticles during the manufacturing
of a pigment concentrate of nano-ZnO in a mineral wax, batch 1
(logarithmic scale at the y-axis). A pre-heating of the mineral
wax, B addition of the dispersing agent, C addition of nano-ZnO,
D measurement of number of nanoparticles near the storage
vessel
All components are assigned to a NRV8h-TWA of
40,000 nanoparticles/cm3. When it is assumed that
the batch processing takes place only once at a working
day, the full production process can be calculated to
have a PCR8h-TWA = 1.32. The 15 min-TWA for the
dispersing agent and the nano-ZnO are: PCR15min-TWA,
dispersing agent = 1.67 and PCR15min-TWA, nano ZnO =
100. Better coverage of the mixing vessel (improved
RMM in batch 2) shows a strong reduction of the
emission resulting for the full production process (2)
in a PCR8h-TWA = 0.46. Also, the short-term peaks
are significantly reduced: for the dispersion agent
PCR 15min-TWA,dispersing agent = 0.01 and for the
nano-ZnOPCR15min-TWA,nanoZnO = 0.08 (see Table 3).
98
___________________________________________________________________________________________
Fig. 6 Boxplot for the
manufacturing of pigment
concentrates for plastics
(batch 1) (background
corrected). Y-axis Number
of particles/cm3, minimum,
P25, median, P75 and
maximum concentrations.
X-axis Average diameter
(nm), minimum, P25,
median, P75 and maximum
particles’ diameter. Batch 1
was prepared in the
morning. Airborne
concentrations were
measured during the process
of mixing of the components
in the wax
Fig. 7 Boxplot for the
manufacturing of pigment
concentrates for plastics
(batch 2) (background
corrected). Y-axis Number of
particles/cm3, minimum,
P25, median, P75 and
maximum concentrations.
X-axis average diameter
(nm), minimum, P25,
median, P75 and maximum
particles’ diameter. Batch 2
was made in the afternoon,
with an identical procedure as
batch 1. The difference is the
better coverage of the mixing
vessel in batch 2
NPs, likely to be PGNPs (especially CombustionDerived NPs), with a maximum of more than 10
million nanoparticles/cm3 close to the emitting
sources (see Fig. 8). It cannot be excluded that ENPs
are emitted during these operations, but if so it is likely
that the ENP concentrations can be neglected compared to the PGNP concentrations.
The average NP concentrations may reach a level
of more than a million of nanoparticles/cm3. An
NRV8h-TWA of 40,000 nanoparticles/cm3 was assigned
to these pollutions. Comparing the average NPconcentrations close to the (continuous) sources and
the hall concentrations with the NRVs show for all
the situations a PCR 8h-TWA 1 assuming a worker
would work for the whole working day in these
surroundings (see Table 3). For short exposure periods
Cutting of the coated non-reflective glass nor the
breaking of glass does not emit NPs in a significant
amount (see Tables 2 and 3).
In the manufacturing of fluorescent tubes the airborne
NP-emission of nano-Al2O3 was sampled during the
preparation of the coating mix for the inside coating of
the fluorescent tubes. This activity does not emit NPs
distinguishable from the background concentration
(see Table 2).
The further coating, sintering, drying and polishing,
in which open fires are used, generate high numbers of
99
___________________________________________________________________________________________
Fig. 8 Average
concentrations of PGNP
from equipment used for
manufacturing fluorescent
tubes. The horizontal grey
bars show the average levels
of PGN Permitted during the
operations of the indicated
machines
average number of particles /cm3
10,000
100,000
1,000,000
10,000,000
H - Wiping machine
I -Adjusntig device
L - Hall AB Hor A1
N - Hall AB
P - Wiping unit (Hall AB)
Q - Sealing machine (Hall AB)
U- Melting (Hall B)
of 15 min the NRV15min-TWA is exceeded as well: PCR
15min-TWA 1 (see Table 3).
exposure control measures taken by the company
during these activities are successfully reducing the
exposure below the NRVs proposed here. The additional personal protection measures taken herein car
refinishing are in line with the current state of the art
advice for personal protection against airborne nanoparticles (which is non-woven protection of the skin
and a HEPA filter respiratory mask).
Long-term wear and lubrication tests
The long-term wear tests in bearing systems show for
the large machines a background-corrected concentration of NP of 21,933 nanoparticles/cm3 (hall a).
Assigning the unidentified emission of PGNPs a NRV
of 40,000 nanoparticles/cm3, this leads to a PCR 8h-TWA
\1. The particles in this area might be conversion
products of the turbine oil or PGNPs generated by the
electrical parts of the machine. The small table-top
machines do not show an emission of NPs.
Comparison of the airborne concentrations
with the Nano Reference Value
Table 3 represents the calculated PCR 8h-TWA and the
PCR 15min-TWA for the activities at the different
workplaces and the related mass-based concentrations.
The calculations were carried out as described in the
methodology section. For some short-term activities
no 8h-TWA concentration was calculated, because the
period the materials are used is only very short. For
these situations the PCR 15min-TWA is estimated.
For the electroplating baths and the manufacturing
of fluorescent tubes, where the NRV8h-TWA are
exceeded it is highly questionable whether ENP are
involved. It is more likely that these activities concern
PGNPs. For the manufacturing of pigment concentrates it is clear that good industrial hygiene measures
(i.e. better closure of the mixing vessel) strongly
reduces the emission.
Short-term exceeding of the NRV15min-TWA is identified for both (nano and non-nano) paint manufacturing
industries, the manufacturing of pigment concentrates
for plastics, the abrasion tests in the electroplating plant
In the overview as presented in Table 3, for car
refinishing a scenario is used that assumes the
measured activity that took place during 4 hours a
day. The emitted particles are assigned a NRV8h-TWA
of 40,000 nanoparticles/cm3. Neither abrasion of
nano-coated metal car parts nor spraying of nanocoating of these parts generate an emission of NP that
exceeds the NRV. Also the abrasion of a plastic
bumper does generate only low amounts of NPs. Also
short-term peak emissions are far below the respective
NRVs shown with a PCR 15min-TWA \1. Spraying of
the conventional coating and the nano-TiO2 coating
generates particles with a diameter [100 nm, and for
the 2-components nanocoating with an average diameter of about 80 nm, presumably being coating
nanoparticles. The measurements suggest that the
100
___________________________________________________________________________________________
industry with regard to the concentrations measured
near the blue passivation bath and the emissions of the
abraser. Here it is the selection of the dominating Cu
particles in the emission that leads to a low BSI
guidance value. Cu has a low established OEL for
coarse material. The other exception where the BSI
guidance value is slightly stricter than the NRVs is
batch 2 of the manufacturing of pigment granulates,
probably due to the relatively strict OEL for coarse
ZnO.
With the Pauluhn methodology the least strict
exposure limits are derived. When these limit values
are used for the assessment, all working situations for
all workplaces are acceptable.
Comparison of the situations where nano-TiO2 was
used with the limit value as derived by NIOSH (2011)
show that workplace environments in paint manufacturing and in the vehicle-refinishing industry remain
considerably below this limit.
and for the coating, sintering, drying and polishing
activities in the manufacturing of fluorescent tubes.
For the paint manufacturing industry it is interesting to find that addition of nano-TiO2 seems not to
generate airborne nanoparticles, while the addition of
the conventional components like solid additives,
CaCO3 and talc seems to generate an emission of
nanoparticles. Some of these emissions may reach
short time high concentration levels. Another option
for these short-term high emissions, like generation of
PGNP by engines or combustion is unlikely, since no
specific changes in activities were observed during the
whole operation (see as well discussion section). In the
situations studied dilution in the workplace air takes
place rapidly and the NRV is exceeded only over a
short distance of the emission source.
The machining and finishing of objects treated with
nanomaterials give rise to a low emission of NPs. The
professional abrasion activities of coated metal parts
and a plastic bumper in the vehicle-refinishing company show that the emission of NPs was below the
NRV, even when equipment-integrated exhaust ventilation is switched off. This suggests that with good
industrial hygiene measures also the emissions for the
abrasion activities in the electroplating industry,
which now give rise to a PCR 15min-TWA [1, may
well be reduced to below the NRV.
An overall look at the type of NPs generated at the
different workplaces shows that in most of the cases it
is highly questionable whether the measured nanoparticles are all ENPs. It is more likely that the emission is
actually dominated by PGNPs. In Table 3 a worst-case
estimation is made of the dominating component of
the measured NPs. With the exception of paint
manufacturing, where the measured concentration of
the NPs can clearly be correlated with the actual use of
nanomaterials, it is likely that other (non-ENP) NPs
contribute significantly to the total NP-concentration.
In those cases a worst-case approach was used to
assign a density to the presumed dominating compounds. In this way the mass concentration of NPs at
the workplace was estimated. A comparison of these
mass concentrations with the suggested BSI-benchmark (BSI 2007) and the Pauluhn approach (Pauluhn
2010) for deriving DNELs for NPs is shown in the
Table 4.
Table 4 shows that for almost all situations the
NRV approach is more strict that the BSI methodology. A possible exception is the electroplating
Discussion
The concept of NRVs was introduced as a tool for
the responsible governance of use of nanoparticles
at workplaces where risk data are limited and a
precautionary approach is indicated (SER 2009).
The metric used for these NRVs, the nanoparticles’
concentration, is uncommon in traditional risk assessment, but has several advantages. One advantage is
that the particle concentration, as measured here, can
be used to estimate the total surface area of the
particles, which has been argued by several authors to
be an advisable metric for nano-effects (Bermudez
et al. 2004; Oberdorster et al. 2004; Abbott and
Maynard 2010; Aschberger and Christensen 2010,
Ramachandran et al. 2011). For a rough estimation one
can use the measured (16 s-average) diameter and
assume a spherical shape of the NPs. For comparison
the particles’ concentration can be converted into the
mass concentration, using an estimate of the density of
the measured nanoparticles. This was done in Table 3,
leading in general to low mass-based concentrations,
never reaching the milligram/m3 range. When these
mass-based concentrations are applied in the Pauluhnalgorithm, which was derived for poorly soluble
spherical particulates (Pauluhn 2010), it is shown that
the NRV-approach is always stricter than this massbased approach (see Table 4). Table 4 shows as well
101
___________________________________________________________________________________________
Table 4 Comparison of the measured NP concentrations with the NRVs and the proposed mass approach of Pauluhn and the BSI
Dominating
compound
DNELP
mg/m3
BSI GV
mg/m3
8 h-TWA
conc/DNELP
8 h-TWA
conc/BSI
C—Passivation bath, non-nano
Organic aerosol
1.08
0.33
0.050
0.165
0.83
5.0
D—Blue passivation bath, nano
Organic aerosol
1.08
0.33
0.081
0.267
1.61
6.0
19.7
I—Rotary abraser, motor
Cu
4.83
0.07
0.001
0.100
0.08
0.8
55.1
J—Rotary abraser, metal
uncoated
Fe
4.24
0.33
0.001
0.009
0.19
22.4
287.9
K—Rotary abraser, metal
electroschel nano
Zn
3.85
0.33
0.000
0.005
0.29
55.1
643.2
M—Rotary abraser, metal coated
non-nano
Metal
3.78
0.33
0.000
0.005
0.26
56.7
649.8
Average
1.62
0.33
0.000
0.002
0.02
10.7
52.6
Activity
8 h-TWA
conc/NRV
8 h-TWA conc
NRV/
BSI
NRV/
DNELP
Electroplating industry
16.5
Full batch preparation
Full process batch 1
Mix components
0.43
0.33
0.960
1.251
1.32
1.1
1.4
Full process batch 2
Mix components
3.03
0.33
0.089
0.820
0.46
0.7
6.5
H—Wiping machine
Soot
1.08
0.01
0.006
0.677
10.80
15.9
1722.6
Soot
1.08
0.01
0.025
2.708
80.97
29.9
3229.4
L—Hall AB Hor A1
Soot
1.08
0.01
0.003
0.333
2.95
8.8
955.4
N—Hall AB
Soot
1.08
0.01
0.040
4.326
38.27
8.8
955.4
Soot
1.08
0.01
0.006
0.669
7.52
11.2
1213.3
Q—Sealing machine (Hall AB)
Soot
1.08
0.01
0.006
0.658
7.65
11.6
1254.9
Soot
1.08
0.01
0.009
0.997
8.82
8.8
955.4
Soot
1.08
0.01
0.009
0.960
8.49
8.8
955.4
Soot
1.08
0.01
0.002
0.176
1.42
8.0
867.3
Average
1.62
0.33
0.002
0.001
0.004
0.269
Soot
1.08
0.01
0.000
0.021
0.55
26.1
2821.5
A—Abrasion conventional
coating M
Polymer
1.08
0.33
0.002
0.007
0.22
31.3
102.4
C—Abrasion conventional
coating R
Polymer
1.08
0.33
0.002
0.005
0.21
41.0
134.3
Polymer
1.08
0.33
0.001
0.003
0.01
2.4
8.0
Nano-TiO2
2.29
0.30
0.002
0.015
0.05
3.1
23.9
H—Abrasion 2-component nano
coating
Polymer
1.08
0.30
0.001
0.004
0.09
20.9
75.4
Nano-TiO2
2.29
0.30
0.000
0.002
0.17
83.9
640.7
N—Spraying 2-component nano
coating
Polymer
1.08
0.30
0.001
0.005
0.71
144.3
519.5
P—Spraying conventional
coating
Polymer
1.08
0.33
0.000
0.002
0.25
156.4
512.0
Full batch preparation
74.7
Italicized value indicates situations where the 8h-TWA exceeds the proposed limit value (or benchmark level). For paint and pigment concentrates
manufacturing only the full batch preparation is presented
Dominating compound is an expert guess
DNELP DNEL derived by Pauluhn, BSI GV BSI Guidance Value
102
___________________________________________________________________________________________
and may de-agglomerate quickly after exposure
(Schulze et al. 2008).
Interesting is the difference in particle diameter
between the abrasion activities of galvanized parts and
the vehicle refinishing, showing for the first particles
with a median diameter of 42–57 nm and maxima
\100 nm, while the latter shows a mean particles’ size
of 60–88 nm, with a 75-percentile and maxima far
above 100 nm. For the latter one may expect an
aggregate of NP and polymer matrix, while in case of
the abrasion of galvanized parts metal NP are expected
to be generated, possibly with a lower agglomeration
potential.
In the current study exposure to nanofibers, such as
carbon nanotubes (CNT), were not studied. Nevertheless, the scheme for the selection of an NRV, as
developed by IFA (2009) was adapted for these group
of substances. IFA restricts the first group solely to
CNTs having asbestos-like effects. However, there
seems to be no good reason to assume that rigid forms
of long non-carbon nanotubes do not exhibit asbestoslike effects (Murphy et al. 2011). Therefore, the scope
of the NRV for this group was extended to rigid,
biopersistent nanofibers for which effects similar to
those of asbestos are not excluded. This includes
non-carbon nanofibers (for which asbestos-like effects
cannot be excluded) as well. Consequently the nanofibers for which asbestos-like effects are explicitly
excluded are allocated to group 3, the biopersistent
granular nanomaterial in the range between 1 and
100 nm with a density of \6.000 kg/m3.
The importance of a special focus on the smaller
NPs of\30 nm is argued by Auffan et al. (2009) who
state that in this size range nano-effects occur, many
particles undergo dramatic changes in crystalline
structure that enhance their reactivity. Choi et al.
(2010) demonstrate that NPs with a hydrodynamic
diameter less than 34 nm and a non-cationic charge
translocate rapidly from the lung to lymph nodes.
They also demonstrate that NPs with a hydrodynamic
diameter of \ 6 nm can translocate rapidly from the
lungs to lymph nodes and bloodstream, and then
subsequently be cleared by the kidneys. In that respect
the lower detection limit of 10 nm of the used
measuring equipment might be a disadvantage. The
manufacturer of the NanoTracer for technical reasons
advised this lower detection limit of 10 nm, as the
diffusion charger used in the apparatus is less efficient
in charging particles with diameters of\10 nm (Marra
that the NRV-approach is mostly stricter than the
mass-based (and scaling-down) BSI approach (BSI
2007). For particulates that have no OEL for the coarse
form BSI did propose to abandon the scaling-down
approach and to use a particle-base approach as well,
using a generic benchmark level of 20,000 nanoparticles/cm3 above the ambient environmental particle
concentration. This approach closely resembles the
NRVs, but does not distinguish between higher and a
lower densities and ignores a size-dependent toxicity.
In that respect the BSI methodology would be stricter
than their mass-based approach and in general stricter
as well than the NRV-approach. NPs in the workplace
have in general a density of\6,000 kg/m3, leading to a
NRV of 40,000 nanoparticles/cm3. Modern measuring
equipment has come available that facilitates measurements of NPs at particle concentrations much
lower than existing equipment for measurements of
mass, allowing the use of NRVs as an affordable risk
management tool, for screening workplace concentrations and avoiding an elaborate and expensive
chemical identification. This means that the use of
NRVs has an advantage over the mass-based
approach. The NRV is in line with the precautionary
principle and gives the opportunity to make explicit
existing uncertainties in composition and toxicity of
NPs in the workplace air. Another advantage is that
the particle number approach allows to use real-time
measuring equipment, which is a large benefit.
Particle concentrations, and average particles’ diameters can be real-time monitored, facilitating source
identification.
The choice in this study to consider NPs with a
diameter \300 nm for the application of NRVs is
outside the limits of the European definition for NPs
which is 1–100 nm (EC 2011), and relates to the used
measuring equipment, that has a cut-off point at
300 nm. But as argued earlier, the EC definition is
legislation/registration oriented, and not risk-oriented.
The 300 nm is as well in line with the arguments of
Scenhir (2009) and of the German Advisory Council
on the Environment that advises the 300 nm limit for
investigation and monitoring, for precautionary reasons (SRU 2011), as summarized in the introduction of
this study. The threshold of 100 nm has been criticized
with the arguments that larger agglomerated particles
retain specific physicochemical properties which are
characteristic for nanomaterials, most likely due to
their relative large specific surface area (Scenihr 2009)
103
___________________________________________________________________________________________
cannot be ignored in risk assessment studies focussed
on the emission of NPs. Thus, this study highlights the
fact that potential hazardous PGNPs may reach
significant airborne concentrations that should be
taken into consideration as well when assessing
handling of the commonly used, relatively simple
‘industrially used’ ENPs. The same holds for NPs
present in conventional compounds that are not
necessarily labelled as ‘nano’, as presumably applies
to certain conventional paint components. This finding
raises the question whether regular risk assessment
procedures should not include the assessment of
potential releases of NPs as well, even in settings
where only conventional compounds are used. For
handling compounds that by nature or due to their
manufacturing procedure may contain a significant
fraction of NP this seems indicated. Therefore, it is
advisable to give the NRVs a wider scope than the
actual limited scope to ENPs. It is advisable to make
them an applicable reference for the assessment of
other NPs as well, as provisional reference value for all
biopersistent airborne nanoparticles used and generated at the workplace.
The measurements of the fluorescent tube manufacturing show significant workplace emissions of
non-engineered NPs up to several million nanoparticles/cm3: probably combustion-derived and possibly
engine-generated NPs (CDNP andEGNP). It cannot be
ruled out that this high emission also hides a small
fraction of the applied ENPs. The composition of the
nanoparticulate emission was not examined, but it is
likely that the combustion processes generate a diverse
group of nanoparticulate materials, consisting of
organic and inorganic components with the ability of
rapid agglomeration, aging by oxidation, which are all
processes that do not necessarily reduce their toxicity
(Donaldson et al. 2005). Electric motors have been
shown to generate Cu NP (Szymczak et al. 2007).
Oxidative stress and cardio-vascular effects have been
associated with exposure to CDNP and engine-generated Cu-particles (Donaldson et al. 2005; Hesterberg
et al. 2010; United States Environmental Protection
Agency (US EPA) 2009).These findings give an
argument to apply NRVs as well in situations with
PGNP emission, as proposed in this article.
For a full risk assessment of the exposure to
nanoparticles at most of the workplace environments
studied here, characterization of the composition of
nanoparticles is necessary. When there is no such
et al. 2010). The measured average diameters were
never \19 nm (Table 2), but this is no proof that
smaller particulates with a diameter \10 nm are not
present in the workplace air. For this measuring
equipment with a lower detection limit would be
needed, but so far no portable equipment with this
feature seems to be available.
The particle concentrations of airborne nanoparticles, as measured during activities in the different
industrial settings, show strongly varying levels. As no
off-line characterisation of nanoparticles has been
carried out, there is ambiguity regarding the nature of
these particles as already pointed out in the results
section. In some cases it is likely that a mixture of the
ENP and NPs generated from other (non-nano) materials is present. This might for example be the case for
the abrasion activities in the electroplating plant and
the car refinishing shop. The presence of ENP and NPs
generated from non-nanomaterials was described earlier for the abrasion of surface coatings (Vorbau et al.
2009; Göhler et al. 2010; Wohlleben et al. 2011). Only
for the paint manufacturing activities, there is a strong
indication that the measured levels of NP are dominated by the materials that were added at that moment.
If so, this would indicate that the emission of ENP
during the manufacturing of nanopaint (especially
nano-TiO2) is very low. However, the measurements
regarding paint production suggest that NPs are
emitted as well during the handling of conventional
components, such as CaCO3, talc and conventional
(‘coarse’)-TiO2. This might mean that conventional
components may contain a substantial amount of
nanosized particles. The fact that the emission of NPs
linked to handling of conventional paint components is
larger than the emission of NPs from handling nanoTiO2 raises questions about the precautionary advice
solely given for the safe use of nanomaterials. One
might argue that precautionary measures should also
apply to conventional materials with a substantial
fraction of NP. The many unknowns concerning the
potential hazardous properties of ENPs as discussed in
the scientific literature hold in principle as well for the
NPs present in conventional paint components. In view
of the recently published EC definition for nanomaterials (EC 2011) this means that compounds registered
as conventional compounds (i.e. having a particle size
distribution with\50% of the amount particles with a
diameter \100 nm), but nevertheless containing a
substantial, potentially dispersive fraction of NPs,
104
___________________________________________________________________________________________
Extending the definition of the NRVs also for 15 minTWA and extending the assessment to particles with a
diameter\300 nm and by making the NRVs applicable
for the assessment of both ENP and PGNP would seem
useful for risk management.
The NanoTracer can be used for real-time screening
measurements and tracing sources of NPs at the
workplace and to check compliance with NRVs as
they have been presented here.
characterization, one might e.g. choose an approach
based on educated guesses about the number of
particles belonging to categories outlined in Table 1
(Nano Reference Values), as was done in the present
article, to find out if further emission or exposure
control measures are indicated.
This study shows that the generic approach with
NRVs is an interesting tool for risk management of
workplaces where exposure to NPs is determined by
NPs with little information on the actual composition of
NP. The study itself gave rise to initiatives of companies
to take measures to reduce workplace emission of NPs
for those (short-term) situations where the NRV was
exceeded. For others it confirmed the effectiveness of
their precautionary protective measures, so they could
motivate their strict orders to workers to wear additional
protective clothing when handling nanoparticles (van
Broekhuizen and Dorbeck-Jung 2012).
Acknowledgments The study was carried out within the
frame of pilot project ‘Nano Reference Values’, commissioned
by the Dutch social partners FNV, CNV and VNO/NCW with a
grant from the Ministry of Social Affairs. Further elaboration of
the results was made possible by a grant of the UvA Holding
BV. The authors like to thank the companies that gave access to
their workplaces (electroplating company, paint, glass, machine
and lightning manufacturers and the vehicle-refinishing shop)
for their participation openness about details of their processes.
The authors also like to thank the Expert panel on Nano
Reference Values for their valuable discussions on the NRV.
The authors like to thank Jan Uitzinger of IVAM for help with
the statistical analysis and creative thinking in presentation of
the data. The comments of anonymous reviewers are gratefully
acknowledged.
Conclusion
The use of solid, dispersable nanomaterials, used for
manufacturing nanoproducts gives sometimes rise to
high airborne NP concentrations near the source
with a rapid dilution further away from the source.
Machining (e.g. abrasion) of surface coated articles
with nanomaterials-containing paint or coating
shows only a very limited emission of airborne
NPs. The contribution of process-generated NPs to
the total airborne workplace concentration of NPs
can be significant. This contribution cannot be
ignored in risk assessment. Interesting is the finding
that it is likely that the handling of some conventional paint components may generate airborne NPs
as well, apparently due to a fraction of NPs in these
compounds. The NP-emission generated by handling
CaCO3 and talc in conventional paint as well as in
nano-paint is in this study considerably larger than
the emission linked to the use of nano-TiO2. Thus,
there is a case to take the emission of NPs into
account as well in the workplace risk assessment of
conventional paints.
The NRV approach as proposed here gives rise to
stricter exposure limits than the mass-based proposals of
Pauluhn and often to stricter exposure limits than the
mass-based BSI proposal. NRVs appear to be a practical
and easy-to-use tool for workplace risk management for
handling or processing of nanomaterials at workplaces.
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Chapter 5 Exposure Limit Values for Nanomaterials – Capacity and Willingness of Users to Apply a Precautionary Approach Accepted for publication in: Journal of Occupational and Environmental Hygiene (2013) 109
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Capacity and Willingness to use Nano Reference Values
Exposure Limit Values for Nanomaterials – Capacity and Willingness of Users to Apply a Precautionary Approach Pieter van Broekhuizena and Baerbel Dorbeck‐Jungb ABSTRACT In the European Union, the legal obligation for employers to provide a safe workplace for processing manufactured nanomaterials is a challenge when there is a lack of hazard information. The attitude of key stakeholders in industry, trade unions, branch and employers’ organizations and governmental policy advisors towards nano reference values (NRVs) has been investigated in a pilot study, which was initiated by a coalition of Dutch employers’ organizations and Dutch trade unions. NRVs are developed as provisional substitutes for health‐based occupational exposure limits (OELs) or derived no‐effect levels (DNELs) and are based on a precautionary approach. NRVs have been introduced as a voluntary risk management instrument for airborne nanomaterials at the workplace. A measurement strategy to deal with simultaneously emitting process‐generated nanoparticles (PGNP) was developed, allowing employers to use the NRVs for risk assessment. The motivational posture of most companies involved in the pilot study appears to be pro‐active regarding worker protection and acquiescent to NRVs. An important driver to use NRVs seems to be a temporary certainty employers experience with regard to their legal obligation to take preventive action. Many interviewees welcome the voluntary character of NRVs, though trade unions and a few companies advocate a more binding status. KEY‐WORDS: Nanomaterials, precautionary approach, Nano Reference Values, Occupational Exposure Limits, Soft Regulation a
Corresponding author: IVAM UvA BV, Plantage Muidergracht 24, 1018TV Amsterdam, Nederlands; e‐mail: pvbroekhuizen@ivam.uva.nl b
University of Twente, Enschede, Netherlands 111
INTRODUCTION The Chemical Agents Directive (1) lays down the minimum requirements for protecting workers from the adverse effects of chemical agents that are present at the workplace, or as a result of any work activity involving chemical agents. In principle these minimum requirements regard nanomaterials as well. Dutch employers are required to assess the risks and control them (2). In the case of nanomaterials for which toxicology information is lacking (3), producers and users of nanomaterials are required to proactively obtain state of the art knowledge about managing exposure and health risk. Considerable gaps exist regarding hazard data and occupational exposure limits (OELs) for nanomaterials. To date attempts have been made to derive health‐
based limit values for only several frequently used manufactured nanomaterials (MNMs): for carbon nanotubes (MWCNT) (4,5,6,7), for fullerenes (C60) (8), for TiO2 (9,10) and for nano‐Ag (5). However, a derivation of an OEL requires large amounts of toxicity data. It is complicated and expensive. Note that the term MNM is synonymous with the term engineered nanoparticle (ENP) as used by other hygienists. The composition of MNMs may be complex, being for example a multi‐component material (e.g. with a surface coating of another composition or a material with specific active sites at the surface) and having a large particle size distribution with a possibly different hazard for different sizes (11,12, 13). The workplace air may also contain incidental nanoparticles that are generated by electrical equipment, or heating or combustion processes. In risk assessment these process‐generated nanoparticles (PGNPs) and agglomerates thereof with MNMs have to be taken into account as well. In view of a lack of data a precautionary approach has been advocated (14, 15). As a provisional alternative to OELs the German Institute for Occupational safety and Health (IFA) has developed benchmark levels for evaluating exposure to MNMs (16). The benchmarks draw on the finding that the surface of the nanoparticles is an important determinant of hazard (17,18,19), and use size, form, biopersistence and density as parameters to distinguish four groups. For low density (<6,000kg/m3) and high density (>6,000kg/m3) granular nanomaterials, with a supposed sphere‐like shape (diameter <100nm) number‐based benchmarks were established corresponding to a mass concentration of 0.1 mg/m³. For carbon nanotubes (CNTs) which possibly exhibit asbestos‐like effects the asbestos OEL is used as a benchmark level. The fourth group regards non‐biopersistent nanomaterials. These benchmarks were further developed as nano reference values (NRVs) by social partners in the Netherlands (20,21,22,23). The four classes of NRVs (8‐hours time‐weighted average; 8‐hr TWA), as adopted by the Dutch Social Economic Council in 2012 (24), are shown in Table 1. 112
Table 1. Nano Reference Values (NRVs) for 4 classes of manufactured nanomaterials Class 1 2 Description Rigid, biopersistent nanofibers for which effects similar to those of asbestos are not excluded Biopersistent granular nanomaterial in the range of 1 and 100 nm 3 Biopersistent granular and fiber form nanomaterials in the range of 1 and 100 nm 4 Non‐biopersistent granular nanomaterial in the range of 1 and 100 nm Density NRV (8‐hr TWA) 0.01 fibers/cm SWCNT or MWCNT or metal oxide fibers for which asbestos‐like effects are not excluded 20,000 particles/cm³ Ag, Au, CeO2, CoO, Fe, FexOy, La, Pb, Sb2O5, SnO2, 40,000 particles/cm³ Al2O3, SiO2, TiN, TiO2, ZnO, nanoclay Carbon Black, C60, dendrimers, polystyrene. Nanofibers with excluded asbestos‐like effects Applicable OEL e.g. fats, NaCl 3
‐ >6,000 kg/m³ <6,000 kg/m³ ‐ Examples NRVs are intended to be precautionary warning levels: when they are exceeded, exposure control measures should be taken. As such, they support compliance with the legal duty to control the health risks of MNMs. Use of NRVs requires measurement of the particle concentration and diameter and requires limited information about the identity of the processed (and measured) MNMs. For identification information is required regarding the shape of the MNMs (fiber or sphere‐like shape), its biopersistency and information on the density of the nanomaterial. NRVs presently are not legally binding. By regarding NRVs as part of the current state of science the Dutch Minister of Social Affairs and Employment has recommended to use NRVs as provisional limit values that should be accompanied by additional measures to minimize exposure (25,26). The Minister’s recommendation can be regarded as a ‘soft’ regulation (27,28). Although not legally binding, this regulatory measure involves certain commitments either to employ the NRVs or to search for alternatives. In 2010 the Dutch social partners initiated a pilot study to investigate whether NRVs are accepted in practice and how relevant actors perceive their usefulness. One of the goals was to explore whether producers and users of nanomaterials are capable and willing to use NRVs. Such information can inform further regulatory action. 113
METHODS The potential of compliance with the NRVs in the Netherlands was studied in a pilot in whom the nanomaterials using industry was involved. Workplace concentrations of nanoparticles (NPs) (and simultaneously their diameter) were measured and compared with NRVs. The results thereof are published elsewhere (21). The measurements were followed by in‐depth interviews with representatives of the involved companies (who were previously informed about the results of the measurements) and with representatives of trade unions, branch organizations and governmental authorities to get insight into perceived feasibility and advisability of the use of NRVs, as well as into activities and ideas to stimulate compliance. The topics of the interviews covered the issues of the requirements of rule compliance, according to the analytical framework that has been developed in regulatory governance studies to get insight into effectiveness issues of soft‐regulation that is established to comply with legal obligations (29,30,31,32,33, 34,35). Governance studies suggest that the successful use of soft regulation in the case of the NRVs first depends on the preconditions of appropriate and easily available measurement strategies at low cost, as well as on adequate information supply about nanomaterials used in products and their possible release during intended use. Second, the potential users of NRVs must know the rules, have a correct understanding of them and have financial resources to employ NRVs. Third, the value of NRVs in practice depends on the willingness of companies to employ them. Willingness builds on ideas on the usefulness of the NRVs, the interests of the companies to use the NRVs, and the compliance culture of the company and the social responsibility within the industrial sector. It builds also on, the available sanctions, pressures/binding force and incentives and pro‐active and knowledgeable oversight and enforcement. Candidate companies were selected based on the MNMs they used. The MNMs had to be biopersistent and insoluble, and present on the OECD list of manufactured nanomaterials (36)
. The companies included manufacturers and users of products containing MNMs, and small to large companies. Low priority was given to the involvement of raw nanomaterial producers, because these appear not to be a key industry in the Netherlands. Involvement of R&D institutes had also a low priority, because these institutes were subject to an earlier study indicating a generally use of small amounts of MNMs and a potentially low exposure (37). Sixty candidate companies were identified, of which 26 were approached and 12 agreed to participate. Some companies refused cooperation without giving a reason or based on their own assessment of low MNMs’ exposure risk (23%). Two companies not using MNMs were included to provide some information on nanoparticulate emissions generated by during conventional activities. Measurements were carried out in 12 companies (Table 2). In‐depth interviews were carried out with representatives from the companies involved (see Table 2), with representatives of R&D institutions involved in health & safety management, with key persons from branch organizations and with governmental authorities. The companies’ interviewees generally were experts involved in health & safety management. In a few cases they were part of the companies’ management board. For the branch organizations and trade unions health & safety policy advisors were interviewed. Interviewed governmental authorities were involved in regulating chemical substances (and 114
nanotechnologies). In total 25 interviews were carried out. Table 3 gives an overview of the interviewees. Table 2 Selected companies for measurement of airborne NPs Type of Industry R&D, Innovation support Paint, coating manufacturer Glass industry Electronic industry Transport industry Construction industry Metal/machine industry Service industry Total Nr 1 4 1 1 1 1 2 1 12 Table 3
Characterization interviews Background interviewee R&D organization Company large Company SME Branch organization Employers’ organization Trade union Governmental authority Labour Inspectorate total Nr 3 5 7 2 1 3 3 1 25 All participating companies and interviewees were informed about the concept of NRVs through an informative flyer, an introductory presentation by the study team, their involvement in measurements, the consequential reporting of the results and a discussion on the consequences with the research team. RESULTS Interviewees emphasize that NRVs are useful only if there is appropriate measuring equipment available. Workplace monitoring of nanoparticles’ concentrations and diameter was provided to the participating companies. For most interviewed companies the actual measurements in the pilot were their first structured activity to assess airborne nanoparticles at the workplace. Some interviewees believed that using a particles/m3 metric for airborne MNMs was not as informative for risk assessment as a mg/m3 metric. Two interviewees stated it was difficult to distinguish airborne MNMs from nanoparticles in ambient air and nanoparticles generated by processes like combustion (or PGNPs). They conclude that NRVs are useful for workplaces that process pure MNMs. Two interviewees from a trade union and a branch organization suggest that extending the scope of the NRVs, to cover both MNMs and PGNPs, is an excellent idea. Their argument is that with the existing uncertainties on the toxicity of both MNMs and PGNPs, the use of a generic NRV covering both sources is appropriate. And, as one of the interviewees put it: “Adopting NRVs, to control both MNMs and PGNPs, is in line with a precautionary approach.” Hazard identification is one of the key‐issues for downstream users of products containing MNMs. In general, the end‐user is not informed about a possible release of MNMs during intended use of the product. The interviewed Labour Inspectorate stated that 70% of 115
the upstream manufacturers do not inform the users of their products about the contained MNMs, because there is no requirement to do so (38). The interviewees from the car repair industry state that downstream users, confronted with this lack of information, are forced to use a precautionary approach for all activities where airborne MNMs might be generated. All of the company appeared to be well informed about existing chemicals legislation and workplace health and safety regulations (1,39). They are acquainted with the concept of OELs. The company interviewees agreed that the legal duty means minimizing exposure to MNMs. They know as well that NRVs are considered to be measures of best practice. Some interviewees conclude that this implies that NRVs are binding, while others are not sure about the binding character. One interviewee emphasizes the warning function of NRVs: “Their value lies in signaling the importance to handle nanoproducts with care”. Another company representative adds that NRVs helps risk management provided that exposure measurements can be carried out reliably. Most interviewees see a direct link between the legal obligation to provide a safe workplace and the use of NRVs. One interviewee summarizes: “NRVs are a good instrument to fulfill the duty of care responsibility, provided there is an efficient way to apply them in practice.” A representative of a trade union stated: “It is clear that the company has to substantiate their activities to control exposures. They have to prove that they take the new risks into account. The NRVs are perceived to be an excellent tool for this. According to another interviewee “NRVs are the latest state of the art of risk management and therefore it is the responsibility of the employer to act accordingly.” Some interviewees hold that additional measures to reduce exposure to nanomaterials at the workplace have to be taken when exposure measurement shows that the NRVs are exceeded. An interviewee from a branch organization notes that a role of the NRVs is to raise the awareness. He thinks that the usefulness of NRVs lies in anticipating coming legislation and mandatory information supply, and a stimulus to become active in relation to the REACH legislation and the safety data sheets (SDS). All interviewees prefer to use OELs based on specific toxicological information for specific MNMs, but they are aware that it will take time before such OELs become available. They recognize that the use of NRVs is a provisional solution and that it is useful to “forestall/reduce fear of employees, industry and consumers.” The NRVs gives reassurance to the company that measures are adequate in view of the current state of science. One of the interviewees remarks that the OELs are limited just as the NRVs are limited because they also involve information gaps and uncertainty. The impression of the research group during workplace visits (21) was, that source oriented exposure control measures in place, were often designed to control the emission of conventional substances. None of the companies involved had installed extra equipment to control NP emissions. One of interviewees stated that his company does not need additional control measures for working with MNMs, because their control measures for conventional hazardous substances (like abrasion dust, welding fumes, isocyanates and organic solvents) are thought to sufficient. On the other hand, one of the companies applies a precautionary 116
exposure control protocol for working with nanomaterials, including separate storage of nanomaterials, the use of additional personal protective equipment for the operations, the registration of personnel involved in working with MNMs, and indirectly as well the personnel involved in transport of MNMs and waste management. Interviewees emphasize that the NRVs motivate a company to consider uncertainty in the degree of health risk posed by MNMs and stimulate a continuous efforts to reduce exposure. Yet, undesirable overprotection is also a concern. An end‐user states that they may lead to unnecessary fears among the employees rather than reassurance. A plant manager remarked that overprotection (irrespective of the use of NRVs) may lead to eliminating the production process using MNMs. In sum. The motivational posture of most of the interviewees (particularly producers) toward using the NRVs can be characterized as pro‐active and acquiescent. Most of them see the usefulness of the NRVs in providing ‘temporary’ certainty, supporting the employer’s legal obligation to care and to take precautionary action, as well as anticipating coming legislation and process innovation. The usefulness is questioned by some end‐users with critical remarks on over‐ or under‐protection of the NRVs. They seem to take the attitude of compromise or disengagement. With regard to social responsibility of the industry interviewees of the chemical and paint industry mention the European Commission’s Code of Conduct (EC‐CoC) for responsible nanosciences and nanotechnologies research (40) and the Responsible Care program of the chemical industry (41). Companies of the chemical sector argue that a culture of responsibility has emerged on the basis of the Responsible Care program, which has been specified in company‐specific CoCs that have been implemented and are controlled and enforced. They stress that the Responsible Care program covers all aspects of corporate responsibility and that there is no need for an additional CoC for nanomaterials and to implement the EC‐CoC. Paint industry interviewees mention their “normal” safety, health and environment measures, referring to the policy to keep the components in the product and to prevent release into the environment. This holds as well for nanomaterials and is stimulated by the employers’ association and the trade unions. These organizations pro‐actively provide on‐line information and organize meetings with companies that use and produce nanomaterials. Furthermore, interviewees feel that the recommendations of the Dutch Social Economic Council (14), the control‐banding tool ‘Stoffenmanager’ (42) and the Guidance working safely with nanomaterials and nanoproducts (43) support the development of social responsibility. With regard to sanctioning, rewarding and other issues of enforcement that can stimulate or hinder the use of NRVs, we draw on an activity that has been run by the Dutch Labour Inspectorate in 2011. (38) This inspection of companies using manufactured nanomaterials concluded that 86% of the inspected companies pays no or too little attention to MNMs in their risk assessment. These companies were warned and committed to live up with their obligation. The Labour Inspectorate referred also to the Social Economic Council’s advice, to apply the precautionary principle when working with MNMs (14). It advised to restrict exposure as much as possible and to use the Guidance for safe working with nanoparticles (43), or a 117
control‐banding tool (42,44) for risk assessment and to guide risk management. Occasionally the inspectors referred to the NRVs as an optional instrument for risk management of MNMs. However, they doubted whether the Inspectorate has the legal right to enforce the use of NRVs (or other risk management measures) in the context of uncertain risks. They observed strong disagreement amongst Dutch lawyers on the question whether the Dutch Labour Law requires application of the precautionary principle. Due to these interpretation problems of the legal frame, inspectors seem to avoid referring explicitly to the precautionary principle. They rather tend to use the employers’ legal duty of care as an incentive for enforcement of employers. DISCUSSION The precondition regarding appropriate information supply is identified as an issue of major concern. Many professional end users seem to be poorly informed about the MNMs in the products they use and their possible release during intended use. At a majority of the inspected companies in the Netherlands MNMs are not taken into account, where mandatory risk assessments are made. The issue of hazard identification, the definition for nanoproducts and the question of what to communicate in the production chain should be addressed to allow for good governance. Within this frame of poor information supply, confidentiality about MNMs used in the products and insufficient knowledge about NPs’ release and possible adverse effects, the NRVs may also be a useful tool for the employer to inform the workers about the potential exposure to NPs (MNMs + PGNPs) and to explain in what way the risk management measures take this source into account. The matter whether NRVs can easily be applied in regulatory practice, emerges particularly in view of their provisional and pragmatic character and the consequential necessity to consider additional control measures, even if exposure remains below the NRVs. Important in this respect is also that the level of the NRVs was shown to be significantly lower than mass‐based proposals for OELs for MNMs (21). The simultaneous generic assessment of MNMs with PGNPs (simply as particle number concentration), as advocated in the pragmatic measurement strategy from the SER (45) (see Figure 1), accepts as a consequence even lower levels for MNMs. But not withstanding the precautionary approach, a guarantee for an absence of health risks below the NRVs cannot be given. As such, NRVs may be regarded as providing temporary certainty. A precautionary approach implies as well an incentive to stimulate research, to find out under what conditions and to what extent exposure to specific MNMs is acceptable. Such research however may take time in view of the pace of toxicological research on nanomaterials and the fundamental emerging questions in the development of the “new” discipline of nanotoxicology (46). An unambiguous acceptance of the NRV‐concept by relevant authorities may solve remaining uncertainties. In this respect, international recognition, as reflected by the discussion in the international workshop on NRVs in The Hague 2011 (23) and the recognition of the NRV concept as an “overarching principle” for risk management at the 7th Joint EU/US Conference on 118
Occupational Safety and Health in Brussels 2012 (47), is a step in that direction. This overarching principle states: “In case exposure limit values are not available for specific nanomaterials a precautionary approach should be applied ‐ generic nano reference values should be considered as a tool for setting provisional limits”. Figure 1. Strategy for workplace assessment of nanoparticles and use of NRVs Measurement in the workplace Correct for background & calculate 8‐hr TWA COMPLIES WITH NRV < NRV No further characterization required > NRV Yes Distinction with measurement strategy possible Concentration manufactured NPs < NRV ?
Distinguish manufactured NPs from PGNP with measurement strategy
Distinction with measurement strategy not possible No UNCERTAIN COMPLIANCE WITH NRV Further chemical/physical characterization of NP advisable DOES NOT COMPLY WITH NRV Risk management measures required With regard to the willingness to use NRVs, participants of the Dutch Pilot accept that for risk assessment and management of nanomaterials, sometimes non‐preferential provisional choices have to be made. The particle number concentration is at variance with the usually mass‐based OELs (17,18,48,49), and requires a change of “mind‐set”. A change of “mind‐
set” is also needed for acceptance of the precautionary approach used for NRVs, though it may be noted that precautionary NRVs, as advised by employers’ organizations and trade unions, are perceived as important. However, it might as well be that the provisional and voluntary character of the NRVs, is experienced as less of a threat, which would be in line with findings of Engeman et al (50), who find that an industry may identify the lack of regulation as a problem due to mistrust regarding responsible behavior of other industry. The voluntary character of NRVs is welcomed as well by governmental policy makers since this characteristic assures that it does not interfere with principles used in existing OHS‐regulation, being based on health or risk considerations. A reason for the easy acceptance of NRVs might also be the finding that 8hr‐TWA exposures to airborne MNMs, as measured in the accompanying pilot project, 119
generally remain below the NRVs, if conventional risk management measures are used (20). For companies these are reassuring findings. The pre‐existing knowledge of the interviewed persons regarding the feasibility of applying NRVs without further organizational or risk management consequences, might lead to a bias favoring acceptance of the concept. Experience of the labour inspectorate shows that active enforcement is an important driver to use supplied risk management tools as the NRV and the control banding tools. Contrasting findings regarding a pro‐active attitude of well‐informed industry are published by Engeman et al (50). These authors conclude that risk perceptions and safety practices are narrow and inconsistent and that because health and safety guidance is not reaching industry a mandatory approach may be the needed. Regarding the interest of companies to forestall more regulation, regulators could clarify that they are forced to come with top‐down measures if NRVs, or well‐underpinned alternative measures to safeguard occupational health and safety, are not used in the work with nanomaterials. CONCLUSION This small pilot study found that most companies working with nanomaterials accept NRVs as a tool to minimize possible adverse health effects among employees. Companies tend to be pro‐active and acquiescent toward using the NRVs for risk assessment and management. An important driver to employ NRVs seems to be a temporary certainty employers experience with regard to their legal obligation to take preventive action. A contribution to the positive attitude of companies towards the NRV may be as well the reassuring finding that conventional exposure control measures are generally adequate as well to control airborne MNMs. Although many of the interviewees welcome the voluntary character of NRVs, trade unions and a few companies advocate stronger regulation. Regulators are recommended to take account of technology‐related preconditions to compliance, like appropriate and easy available measurement strategies at low cost; appropriate information supply about nanomaterials used in products and their possible release during intended use. The NRV pilot study shows how important these preconditions are for compliance. 120
ACKNOWLEDGEMENT The study was carried out within the frame of pilot project “Nano Reference Values”, commissioned by the Dutch social partners FNV, CNV and VNO/NCW with a grant from the Ministry of Social Affairs. Further elaboration of the results was made possible by a grant of the UvA Holding BV. The authors like to thank the companies that gave access to their workplaces (electroplating company, paint, glass, machine and lightning manufacturers and the vehicle refinishing shop) for their participation openness about details of their processes and readiness to participate in the interviews. The authors like to thank as well the trade union officers, branch and employers’ organizations’ officers and policy advisors of the governmental institutions that were ready to participate in the interviews as well. The helpful comments of the anonymous reviewers are gratefully acknowledged. 121
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128
Chapter6
Comparison of control banding tools to support safe
working with nanomaterials and the role of processͲ
generatednanoparticles
Submittedto:
AnnalsofOccupationalHygiene(2012)
129
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130
Comparison of Control Banding Tools
___________________________________________________________________________________
Comparison of control banding tools to support safe working with
nanomaterialsandtheroleofprocessͲgeneratednanoparticles
PietervanBroekhuizen1,2,HildoKrop1,LucasReijnders3
Abstract
Threequalitativecontrolbandingtools,the‘Guidance’,the‘ControlBandingNanotool(CBN)
and the Stoffenmanager Nano (SMN), that estimate risks of working with manufactured
nanomaterials (MNM), are applied to eight different working environments and compared
with the Precaution Characterisation Ratio (PCR), derived from former measurements of
nanoparticles’ number concentrationsat these workplaces. It was found that theestimated
risk levels may vary, but the recommended engineering control does not necessarily differ.
Differencesinprecautionaryapproachregarding‘unknown’hazardandexposuredataleadto
differencesinestimatedrisklevels.TheCBNandtheSMNestimateahighriskespeciallywhen
hazarddataarelacking.TheGuidanceestimatesahighrisklevelwhendispersiveMNMsare
used.ItwasobservedthatthesensitivityforhazarddataisrelativelyhighintheSMN,andlow
intheCBNandtheGuidance,whilethesensitivityforexposuredataisrelativelyhighforthe
CBNandlowfortheSMNandtheGuidance.
At several workplaces high PCR values are observed where heating or combustion
processes take place or where electrical equipment is used, most likely resulting from the
formation of processͲgenerated nanoparticles (PGNP). These nanoparticles’ sources are not
taken into account by the control banding tools. It is argued that when a workplace risk
assessmentfornanomaterialsiscarriedout,PGNPsshouldbetakenintoaccount.
All three tools may contribute to raising the awareness of industries and workers
aboutthepotentialrisksofnanomaterials.
Keywords: Nanomaterial, Risk Management, ProcessͲGenerated Nanoparticles, Control
Banding,NanoReferenceValue,Guidancesafeworking
Introduction
Risk assessment of the occupational use of manufactured nanomaterials (MNMs) and nanoͲ
enabledproductsiscomplicatedbyseveralfactors,amongstwhichlackofappropriatehazard
data and relevant exposure data and conceptual issues related to physical/chemical and
biological properties of MNMs relevant for the toxicological behavior are frequently
mentioned(Brouwer2010,Shvedovaetal2010,Yokeletal2011).Also,inworkingwithMNMs
1
IVAMUvAbv,PlantageMuidergracht24,1018TVAmsterdam,Netherlands
Correspondingauthor:tel+31205256324;eͲmail:pvbroekhuizen@ivam.uva.nl
3
UniversityofAmsterdam,InstituteforBiodiversityandEcosystemDynamics,Amsterdam,Netherlands
2
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theretendstobeexposuretoothernanoparticlesthanMNMs:backgroundnanoparticlesand
nanoparticlesoriginatinginworkͲrelatedprocesses(ECHA2012c).TheEuropeanCommission
acknowledges this in its recommendation for a definition of nanomaterials as natural and
incidentalparticles(EC2011).Inthepresentstudy‘incidental’nanoparticlesgeneratedbythe
workplaceͲrelatedsourcesarecollectivelycalledprocessͲgeneratednanoparticles(PGNP).The
existing ambient background nanoparticles’ concentration originate from natural processes
likevolcanicactivities,naturalfires,anderosionprocessesandfromanthropogenicsourcesas
traffic, smoking, heating and cooking (among many others: Morawska et al 2008). The
generationofnanoparticlesformedatworkplacesbyworkͲrelatedprocesses,simultaneously
totheuseofMNMsincludecombustionprocesses(Donaldsonetal2005),soldering,welding,
use of electrical equipment and fracturing and abrasion activities like sanding, milling and
drilling. Scymczak et al (2007) demonstrated that universal electrical motors emit
nanoparticles with a high content of copper. In manufacturing processes conventional
comͲpounds, which contain a nanoͲsized particles’ fraction, may also be used, giving rise to
emissions of nanoparticles at the workplace (van Broekhuizen 2012a). Assembly formation
(agglomeration and aggregation) of nanoparticles from the different sources may further
complicateidentificationandallocationofthemeasurednanoparticlestothespecificsource.
Several Control Banding (CB) tools for qualitative risk characterization and
managementofworkplacehazardshavebeenspecificallydevelopedforMNMs(Schulteetal
2008;Paiketal2008;Zalketal2009;ANSES2010;Höcketal2010;ICON2010;Hansenetal
2011; Cornelissen et al 2011; DuurenͲStuurman et al 2012). Most tools define defaults for
unknownsfordealingwiththelackinhazarddataanduncertaintiesregardingpossibleeffects
andthelimitedexposureinformationofMNMs.UsingaCBͲtoolmayforestallthenecessityto
carryoutexposuremeasurements,butitshouldbenotedthatacontributionofPGNPstothe
workplacehazardsisgenerallynottakenintoconsiderationintheMNMͲspecificCBͲtools.The
CB strategies allow categorizing workplace risks into control bands based on evaluations of
hazardandexposureinformationofMNMs.TheCBtoolsmaydifferregardingtheendpoints
they select for risk evaluation. Brouwer (2012) evaluated several of the CB tools for
nanomaterialsandconcludedthatthereisaneedtochecktheperformanceofthetools,tofill
theknowledgegapsandtoextendthevaliditydomainforexposure.
Anotherapproachtodealwiththelackofhazarddataanduncertaintiesinknowledge
about hazards uses nano reference values (NRVs) and the precaution characterization ratio
(PCR),asatoolforprecautionaryriskmanagementofMNMswhenhealthͲbasedoccupational
exposurelimits(OELs),orderivednoͲeffectlevels(DNELs)arenotavailable(SER2012).
This paper seeks to compare risk estimates and control measures that emerge from
applyingthecontrolbandingtoolsGuidanceforworkingsafelywithnanomaterials(Guidance),
the Control Banding Nanotool (CBN) and the Stoffenmanager Nano (SMN) with measured
workplace concentrations, as evaluated with NRVs by using the PCR. These tools are
elaboratedintheMethodssection.
Two questions are raised. The first is: “Do MNMͲspecific CB tools when applied at the same
workplaces lead to similar risk estimates for control measures and how do these relate to
132
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measuredconcentrations?”Thesecondis:“IsitlegitimatetoignorePGNPsinriskassessment
andriskmanagementwhenassessingMNMs?”
ForthispurposetheGuidance,theCBN(Paiketal2008;Zalketal2009)andtheSMN
(DuurenͲStuurman et al 2012) are applied at eight previously studied working environments
(van Broekhuizen et al 2011, 2012a). The activities in these working environments are
summarizedinBox1.Therecommendationsforsafeworkinglinkedtotheserisklevelswillbe
outlined. These recommendations are comparedwith recommendations basedon exposure
measurementsasrelatedtoNRVsfroma
previous study (van Broekhuizen et al Figure1, Source–receptorschemeandscopeofthetools
2012a).
Transmission
The Guidance was selected
Imission
Emission
becauseitwasdevelopedbytheauthors
(Cornelissen et al 2011), the CBN was
Worker
Source
selectedasatoolestimatingtheemission
potential of MNMs, the SMN because it
estimates the immission potential
SMN
GuidanceandCBN
including the existing control measures
(seefigure1).Thethreecontrolbandingtoolsshareasimilarconceptbydistinguishinghigh,
mediumandlowrisksbasedonMNMs’hazardsandestimatedexposure.
Methods
TheGuidance,theCBN,theSMNandtheNRVconceptarebrieflyexplainedinthissection.
GuidanceforworkingsafelywithnanomaterialsandnanoͲenabledproducts
The Dutch social partners (employers’ organizations and trade unions) developed the
Guidance as a laymanͲoriented guidance, to be used as simple guide for qualitative risk
assessment when only minimal information about the MNMs properties and hazards is
available (Cornelissen et al 2011). Control measures are advised based on the estimated
emission potential. The Guidance is recently being combined with the NRVͲapproach
(Broekhuizen2012b).
The guidance uses a stepͲbyͲstep approach. Hazard and exposure data are collected and
combined in a decision matrix to establish a control level (figure 2). For characterization of
MNMsdataareusedthatinprinciplecanbefoundonthematerialsafetydatasheet(MSDS)
or technical data sheet of the product. Three hazard bands are defined in line with the
approachfortheNRVs(seetable1)(Broekhuizenetal2012c).Threeexposurepossibilitiesare
distinguished (see figure 2). A combination of the health hazard bands with the exposure
probabilitybandsdefinesthreeriskmanagementclasses:ahigh(A),medium(B)andlow(C)
(seefigure2).Thetieredoccupationalhygienestrategy(OHS)isusedtoselecttheappropriate
controlmeasure,meaningthatthemandatoryorderofprioritiesisusedforcontrolmeasures
aslaiddownintheEUChemicalAgentsDirectiveorCAD(1998),andasoperationalizedinthe
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Dutchlegislationbythereasonablenessprinciple(Arboportaalnd).Thisprincipledetermines
thatitisnotallowedtochoosealowercontrollevelunlesstherearetechnical,operationalor
economicbarrierstoapplyahighercontrollevel.Theadviceforlowrisk(C),mediumrisks(B)
andhighrisk(A)situationsisdescribedintheexplanationoffigure2.Forthehigherrisklevels
AandBitisadvisedtoapplypracticalexposuremeasurementsandtoapplyOELsorNRVsfor
riskmanagementandtodistinguishMNMsfromPGNPs.TheGuidanceprovidestheuserwith
alistofpossibleexposurecontrolmeasuresthatcanbeimplementedtolowertheexposure.
Figure2.
Decision matrix to determine the risk management class and the control level for
activitieswithnanomaterialsandnanoͲenabledproducts(Guidance).
Descriptionofthehazard
categoryforeach
nanoͲenabled
product
Probabilityofexposureto
nanoparticlesduringactivities
Hazard
category1
Hazard
categories2aand2b
Hazard
category3
Rigid,biopersistent
nanofibersforwhich
asbestosͲlikeeffectsare
notexcluded
Biopersistentgranularand
fiberformnanomaterials
withexcludedasbestosͲlike
effects
NonͲbiopersistent
granularor(water)
solublenanomaterial
A
A
C
A
B
C
B
C
C
ExposurecategoryI:
Emissionofprimarynanoparticlesispossible.
ExposurecategoryII:
Emissionofnanoparticlesembeddedinalarger
solid(>100nm)orliquidmatrixispossible
ExposurecategoryIII:
Emissionoffreenanoparticlesminimiseddueto
workinginfullcontainment
Explanationriskmanagementclasses:
A
ThehierarchicOccupationalHygienicStrategywillbestrictlyappliedandallprotectivemeasuresthatarebothtechnicallyand
organizationallyfeasiblewillbeimplemented.Thereasonablenessprincipleisnotused.
B
AccordingtothehierarchicOccupationalHygienicStrategy,thetechnicalandorganizationalfeasibleprotectivemeasuresare
evaluatedastotheireconomicfeasibility.Controlmeasureswillbebasedonthisevaluation
C
Applysufficient(room)ventilation,ifneededlocalexhaustventilationand/orcontainmentoftheemissionsourceanduse
appropriatepersonalprotectiveequipment
TheControlBandingNanotool(CBN)
The CBN was developed as an “easy to use tool” by Paik et al (2008), updated by Zalk et al
(2009) and is available in an Internet version: the CB Nanotool 2.0 (CBN 2010). The CBN
estimates the emission potential of MNMs. The authors state that the CBN strategy may be
particularly useful in nanotechnology applications, considering the overwhelming level of
uncertaintyoverwhatpotentialoccupationalhealthrisksnanomaterialspresent,andtoassess
andmanagetherisks.Therisklevel(RL)ofanoperationresultsfromcombiningaseverityand
a probability score. The severity score identifies 15 hazard factors to estimate the potential
hazardoftheMNM.Thesesumtoamaximumhazardscoreof100points.70ofthesepoints
arebasedoncharacteristicsofthenanomaterialand30pointsarebasedoncharacteristicsof
theparentmaterial.Theresultingseverityscoredistinguishesfour“severities”:low,medium,
highorveryhighseverity,eachinabandof25points.TheMNMͲspecificseverityfactorsare:
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surface reactivity, particle shape, particle diameter, solubility; for both the MNM and the
parent material: the carcinogenicity, reproductive toxicity, mutagenicity, dermal toxicity,
asthmagenicity;fortheparentmaterialalsotheoccupationalexposurelimit(OEL)isused.The
probability score identifies 5 exposure factors determining the potential exposure of
employees to nanoscale materials, primarily through inhalation, but dermal contact is also
takenintoaccount.Thesesumtoamaximumprobabilityscoreof100.Theprobabilityfactors
are: estimated amount of nanomaterial used during task, dustiness/mistiness, number of
employees with similar exposure, frequency and duration of the operation. If scoring of the
severity or probability factor is not possible due to unknowns, a default of 75% of the
maximumscoreforthatfactorisassigned.Combiningtheseverityandtheprobabilityscorein
a4x4matrixdeterminestheoverallriskleveldistinguishedin4risklevels.Thefourthrisklevel
recommending “specialists advice” for engineering controls is used for special cases (but is
neverusedinthecurrentstudy).
StoffenmanagerNano(SMN)(vanDuurenͲStuurmanetal2012)
The SMN is an InternetͲbased CBͲtool (SMN 2011), estimates the potential emission of the
considered nanomaterial and calculates the immission of MNMs. The SMN combines hazard
and exposure bands in a 5x4 matrix, establishing a ‘priority band’ (or risk level). Hazard
banding is a stepͲbyͲstep procedure including the following steps: (1) determination of the
water solubility, (2) presence of persistent nanofibers, (3) classification of MNMͲspecific
hazardsand(4)classificationofinsufficienttoxicologicaldata.Thereare5hazardbands.The
default for unknown hazards is given a high priority in case they fall into a relatively high
exposure band. The exposure band is based on the conceptual model as described by
Schneideretal(2011).ThemodelgivesadetaileddescriptionofthetransferoftheMNMfrom
the source to the worker and identifies the following relevant factors: intrinsic substance
emission potential, handling (activity emission potential), localized controls, segregation
(enclosureofthesource),dilution/dispersion,personalbehavior,separation(enclosureofthe
worker), surface contamination, and use of protective respiratory equipment. These factors
are weighted by assigning a ‘multiplier’ to generate the score for the exposure band. SMN
takestheexistingcontrolmeasuresintoaccountandprovidestheuserwithalistofpossible
control measures that can be implemented to lower the exposure, leading to a renewed
prioritization. The SMN cannot be applied to abrasion activities and physical fracturing
operations. For these operations the authors refer to the general Stoffenmanager tool for
chemicalsubstances(VanDuurenͲStuurmanetal2012).
NanoReferenceValuesandthePrecautionCharacterisationRatio
Nanoreferencevalues(NRVs)weredevelopedtoprovideprovisionallimitvaluesinsituations
where recognised OELs and DNELs are not available (SER 2012). NRVs represent a warning
level: when they are exceeded, exposure control measures should be taken. Use of NRVs
requires measurement of the particles’ number concentration and diameter and requires
limited information about the identity of the processed (and measured) MNMs. For MNM
135
___________________________________________________________________________________
identification, information is required regarding the shape of the MNMs (e.g. fibre or
spherical),theirbiopersistencyandinformationaboutthedensityoftheMNM.DetailsofNRVs
for different classes of MNM are set out in Table 1. NRVs are precautionͲbased normative
quantifiers.TheyarenothealthͲbasedbutunderlyingtheNRVͲconceptistheevidencethatthe
nanoparticles’ number and surface area are likely to influence the hazard of low solubility
particles[Bermudezetal2004;Oberdörsteretal2004;AbbottandMaynard2010;Aschberger
and Christensen 2011]. NRVs are generic values developed for MNMs, but in view of the
likeliness that PGNP have similar hazardous properties as MNMs (SCENHIR 2009) it was
suggestedtomakethemaswellapplicabletoPGNPsasaworstͲcaseapproach(Broekhuizen
2012a). However, an international panel preferred to distinguish MNMs and PGNPs in a
separateevaluation(Broekhuizen2012c).
Table1 NanoReferenceValues(NRVs)for4classesofmanufacturednanomaterials
Class Description
Rigid,biopersistentnanofibers
1 forwhicheffectssimilartothose
ofasbestosarenotexcluded
Density
Ͳ
NRV(8ͲhrTWA)
3
0.01fibers/cm Examples
SWCNTorMWCNTormetaloxidefibers
forwhichasbestosͲlikeeffectsarenot
excluded
Biopersistentgranular
2a nanomaterialintherangeof
1and100nm
>6,000kg/m³
20,000particles/cm³
Ag,Au,CeO2,CoO,Fe,FexOy,La,Pb,Sb2O5,
SnO2,
Biopersistentgranularandfiber
2b formnanomaterialsintherange
of1and100nm
<6,000kg/m³
Al2O3,SiO2,TiN,TiO2,ZnO,nanoclay
CarbonBlack,C60,dendrimers,polystyrene
NanofiberswithexcludedasbestosͲlike
effects
Ͳ
ApplicableOEL
NonͲbiopersistentgranular
3 nanomaterialintherangeof
1and100nm
e.g.fats,NaCl
The NRV is established as a backgroundͲcorrected, 8hourͲTWA (Time Weighted Average)
exposurelevel.Forshortexposureperiodsof15minͲTWAashortͲtermNRV15minͲTWAisused,in
analogy with the common risk management approach of the Dutch Labour Inspectorate for
assessing shortͲterm exposures to chemical substances [SDU 2006]: NRV15min,TWA = 2 x
NRV8hr,TWA.
ThePrecautionCharacterizationRatio(PCR)isdefinedasthequotientofthemeasured
concentrationofNPsandtheNRV(SER2012):
ܲ‫ܴܥ‬௜ ൌ
݊‫ܲܰ݊݋݅ݐܽݎݐ݊݁ܿ݊݋ܿݎܾ݁݉ݑ‬௜
ܴܸܰ௜
PCR>1indicatesthattheNRV8hrͲTWAisexceeded.Inthiscasethesourceofthenanoparticles’
emission(s)shouldbeidentifiedandpossibilitiestoreducetheemissionofnanoparticlesmust
be assessed. The PCR8hrͲTWA and the PCR15minͲTWA for the workplaces discussed here is
graphicallypresentedinfigure3.
Workplacesstudied
The tools were applied at eight workplaces for which earlier studies measured airborne
nanoparticles’ number concentrations(van Broekhuizen et al 2011 and 2012a). Box 1 briefly
characterizes these workplaces. The measured backgroundͲcorrected nanoparticles’ number
136
___________________________________________________________________________________
concentrationsinthestudieswereexpressedasPCR.Thebackgroundwasconsideredtobeof
natural or anthropogenic origin and measured at workplaces avoiding contamination with
nanoparticlesemissionsfromproductsorprocesses(e.g.intheearlymorningwithequipment
still in the switchedͲoff position). The PCR data used are presented in table 2. It should be
noted that van Broekhuizen et al (2011 and 2012a) conclude that processͲgenerated
nanoparticles(PGNPs)contributetothetotalexposuretonanoparticlesatmanyworkplaces,
andthatitislikelythattherearesituationsinwhichPGNPsdominatethetotalnanoparticles’
numberconcentrationsattheworkplace.
Box1
Workplacesandactivitiesstudied(seevanBroekhuizenetal2011,2012a)
1.
Electroplating:dippingactivitiesofcomponentsinapassivationbaththat,accordingtotheMSDS,makesuseofa
componentwithavalencyof3,whichispresumablyCr(III)(Cr2O3?).Workplacewithgeneralventilation.
2.
Paintmanufacturing:mixingoperationduringmanufacturingofawaterbasedwallpaintwithnanoͲTiO2..Mixingvessel
withlocalexhaustventilation.
3.
Productionofpigmentconcentrates:nanoͲZnOparticlesaremixedinameltedwax.Fumehoodabovemixingvessel
(localexhaustventilation–LEV)(3a).Improvedemissioncontrolwasrealisedbyincludingfullenclosureofthemixing
vessel(3b).
4.
NonͲreflectiveglassproduction:glasswithasilicacontainingnanoͲlayerisfurtherhandledbycutting(4b)andbreaking
(waste)(4a)oftheglasspanels.Workplacewithgeneralventilation.
5.
Lightequipmentmanufacturing:ThefocuswasputontheproductionofananoͲAl2O3dispersioncoatinginafully
enclosedmixingvessel(5a).Thecoatingisappliedtotheinsideofglasstubesandfurtherhandledinavarietyof
productionstepstogenerateafinishedproduct(5bͲj).Thefinishingstepsrequiremechanicalpolishingstepsandsteps
withhightemperaturegasheating.Workplacewithgeneralventilation,someheatingmachinesareexhaustventilated.
6.
Carrepair:abrasionandsprayingoperationsarecarriedout,usingananoͲTiO2coating(6a,c)anda2Ͳcomponent
nanocoating(withunknownnanomaterials)(6b,d).Localexhaustventilatedwall.
ApplicationofaselfͲcleaningcoating:outdoorglasswindowsaresprayͲcoatedwithananoͲTiO2containingcoating.No
ventilationmeasures.
7.
8.
Constructionindustry:nanoͲsilicaismixedoutdoortopreparehighͲstrengthmortar.Noventilationmeasures.
137
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Table2 Precaution Characterisation Ratio (PCR) for an 8hrͲTWA and 15minͲTWA at different workplaces
correctedforthebackground(Reference:Broekhuizenetal2011;2012a)
Event
Electroplatingindustry
Ͳ passivatingbath
3a
3b
ManufacturingnanoͲwallpaint**
Manufacturingpigmentconcentrates
Ͳ AddingnanoͲTiO2topaintmix
Ͳ DispersingZnOinmixingvessel
Ͳ Idem,improvedemissioncontrol
TiO2
ZnO
ZnO
4a
4b
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
6a
6b
6c
6d
7
8
ProductionofnonͲreflectiveglass
Manufacturingfluorescenttubes
Carrepair
Sprayapplicationcoating(outdoor)
Constructionindustry(outdoor)
Ͳ Dumpingwasteglass
Ͳ Glasscutting1
Ͳ DispersionAl2O3inmixingvessel
Ͳ Wipingmachine
Ͳ Adjustingdevice
Ͳ HallABLocationA1
Ͳ HallAB
Ͳ Wipingunit(HallAB)
Ͳ Sealingmachine,(HallAB)
Ͳ Melting(HallB)
Ͳ Pumpingmachine(HallB)
Ͳ Polishingproduct
Ͳ AbrasionnanoͲ TiO2coating
Ͳ Abrasion2ͲCnanocoating
Ͳ SprayingnanoͲTiO2
Ͳ Spraying2ͲCnanocoating
Ͳ SprayingselfͲcleaningcoating
Ͳ Mixingmortar
1
2
Form
MNM
ld
sp
sp
sp
PCR
8hrͲTWA
1.61
0.02
5.00
0.03
PCR
15minͲTWA
*
0.37
100
0.08
SiO2
SiO2
Al2O3
Ͳ
sc
sc
Sp
sp
sp
sp
sp
sp
sp
sp
sp
TiO2
?
TiO2
?
TiO2
SiO
sc
sc
ld
ld
ld
sp
0.00
0.00
0.00
10.80
80.97
2.95
38.27
7.52
7.65
8.82
8.49
1.42
0.05
0.09
0.17
0.71
0.00
0.01
0.03
0.00
***
5.26
50.00
1.47
20.00
3.70
3.85
4.35
4.17
0.71
0.03
0.14
0.12
0.64
0.00
0.13
MNM
present
Cr2O3?
FormMNM:ld=liquiddispersion;sp=solidparticles;sc=solidcoating
*
continuousprocess,nopeaksidentifiedduringtheactivities
**
8hr TWA calculated over the full paint mix production cycle. 15min TWA only over the period of adding
nanoͲTiO2.
*** nopeaksidentifiedduringtheactivitiesAl2O3
Results
Risk assessments of the eight case studies with the Guidance, the CBN and the SMN are
summarizedintable3.Thecomparisonisgraphicallypresentedinfigure4.Comparisonofthe
estimated risk levels generated with the three tools shows differences for the same
operations,buttherecommendationsforsafeworking,basedintheestimatedrisklevels,do
notnecessarilyleadtodifferentcontrolmeasuresaswillbeexplainedbelow.
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___________________________________________________________________________________
Table3, ComparisonoftheriskassessmentsforeightactivitieswithnanomaterialswiththeGuidance,theCBN
andtheSMN
Guidance
ControlBandingNanotool
Hazard
band
Exposure
band
Risk
Level
Severity Probability
band
band
3Ͳ2b/2aͲ1
IIIͲIIͲI
CͲBͲA
LͲMͲH
2b(?)
II
B
H
StoffenmanagerNano
Risk
level
Hazard
band
Exposure
Band
Risk
Level
EULͲLLͲLͲP
1Ͳ2Ͳ3Ͳ4
AͲBͲCͲDͲE
1Ͳ2Ͳ3Ͳ4
IIIͲIIͲI
EUL
2
E
1
I
Nr
Event
1
Electroplatingindustry
2
Manuf.nanoͲwallpaintͲAddingnanoͲTiO2
2b
I
A
M
L
2
C
1
III
3a
3b
Manuf.pigmentconc.
ͲDispersingZnO
ImprovedexhaustcontrolͲDispersingZnO
2b
2b
II
III
B
C
M
M
L
L
2
2
C
C
1
1
III
III
4a
4b
5a
ProdnonͲreflectiveglass ͲDumpingglass
ͲGlasscutting1
2b
2b
II
II
B
B
M
M
LL
L
1
2
n.a.
n.a.
n.a.
Manuffluorescenttubes ͲDispersingAl2O3
2b
I
C
L
L
1
B
1
III
5b
5c
5d
5e
5f
5g
5h
5i
5j
6a
6b
6c
6d
–Wipingmachine
–Adjustingdevice
–HallABHorA1
–HallAB
–Wipingunit(HallAB)
ͲSealingmachine,(HallAB)
ͲMelting(HallB)
–Pumpingmachine(HallB)
ͲPolishingproduct
CarRepair
ͲAbrasionnanoͲTiO2coating
ͲAbrasion2ͲCnanocoating
ͲSprayingnanoͲTiO2
ͲSpraying2ͲCnanocoating
2b
II
B
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
2b
2b(?)
2b
2b(?)
II
II
II
II
B
B
B
B
M
H
M
H
L
L
L
L
2
3
2
3
n.a.
n.a.
C
E
n.a.
n.a.
1
1
n.a.
n.a.
III
I
7
SprayapplcoatingͲExteriorsprayingcoating
2b
II
B
M
L
2
C
1
III
8
Constructionindustry
ͲMixingmortar
2b
I
A
L
L
2
C
1
III
*
Ͳpassivatingbath
Explanation:
*Thethirdlinepresentsthedifferentbandsinmountingorder,fromlowtohigh.
Guidance: Hazardband:1,2a,2band3,where1=highestand3=lowesthazard(explanationseetable1)
Exposureband:I,II,andIIIwhereI=highestandIII=lowestexposure(seefigure2)
Risk(Control)level:A=highest;B=Medium;C=lowest
2b(?)=UnknownnanoͲcomponent
Severityband:H=high;M=medium;L=Low
CBN;
Probabilityband:EUL=Extremelyunlikely;LL=Lesslikely;L=Likely;P=Probable
Risklevel:1=low(Generalventilation);2=medium(fumehoodorlocalexhaustventilation);3=high
(Containment);4=Unknown(Seekspecialistadvice)
HazardBand:AͲD,E,whereAislowandDishighrisk,E=unknown(Seekspecialistadvice);
SMN;
ExposureBand:Class1–4where1=lowestexposureand4=highestexposure.
RiskLevel(Riskpriorityband):I,IIandIII,whereI=highestprioritytotakemeasures;III=lowest
priority.
n.a.
Notassessed.SuchactivitiescannotbeassessedwiththeCBNandStoffenmanagerNano.
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___________________________________________________________________________________
Figure3 GraphicalrepresentationofPCRsforthedifferentworkplaces(seebox1andtable1fordetails)
(DatafromvanBroekhuizenetal2011and2012a)
100
PCR 10
1
0,1
0,01
1
2
3a
3b
4a
4b
5a
5bͲj
6a
6b
6c
6d
7
8
Differentworkplaces
PCR8hrͲTWA
Explanation:
PCR15minͲTWA
Seebox1andtable1foradescriptionofthedifferentworkplaces.
PCR>1forworkplaces1,3and5bͲj.Fortheworkplaces5bͲj(9differentworkplaces)theaverage
PCRisrepresented.Forworkplaces4a,4b,5aand7thenanoparticles’numberconcentration=
0(PCR8hrͲTWA=0)
Therepresentedvaluesarecorrectedforthebackgroundconcentrations
Activities5bͲjareprocessingoperationswithstronglyvaryingemissions,supposedlyfrom
PGNPs.Anarithmeticmeanoftheseemissionsispresented.
Figure4 ComparisonofestimatedrisklevelsfordifferentactivitieswithMNMs
Riskband
3
2
1
0
1
2
3a
3b
4a
4b
5a
5bͲj
6a
6b
6c
6d
7
8
Activity
Guidance
CBN
SMN
Explanation:
Seebox1andtable1foradescriptionofthedifferentworkplaces.
Tofacilitatecomparisonofthetoolstherisklevelsofthedifferenttoolswerebroughtinlineby
usingidenticalnumbers:risklevel1=‘low’risk;risklevel2=‘medium’risk;risklevel3=‘high’
risk.(ThereforetheGuidanceriskbandswererenumbered:A=3,B=2andC=1;theSMNrisk
bandswererenumberedoppositely:I=3,II=2,III=1).NB:riskband4asdefinedintheCBNwas
neverestimatedinthecasesstudied.
Workplace 1 regards fullͲday electroplating operations in a fluid nanoͲenabled bath. Existing
measuresattheworkplacearegeneralventilationoftheproductionhall..Workplace1hasa
140
___________________________________________________________________________________
PCR8hrͲTWA >1. The Guidance and CBN rank the risk as ‘medium’; the SMN ranks the risk as
‘high’ due to the uncertainty regarding the nanoͲcomponent. Van Broekhuizen et al (2012a)
notethatitislikelythatthenanoparticles’numberconcentrationisstronglydominatedbyNPs
generatedbytheprocessesappliedandequipmentused(PGNPs).
Workplace 2 regards the manufacturing of nanoͲTiO2 paint. Existing measures are
localexhaustventilation,generalventilationofthehall,andpersonalprotectiveequipmentair
respirator, gloves and protective clothing. The 8hrͲTWA regards the manufacturing of a full
batchofnanoͲenabledpaint,whichincludestheaddingofdifferentcomponentsthatcontaina
fraction of nanoparticles. The 15minͲTWA was calculated over the adding of the nanoͲTiO2
only. TheGuidanceestimatesahighrisklevel,advisingtotakeallpossiblemeasurestoreduce
theexposure;theCBNestimatesamediumlevel,advisingtoapplylocalexhaustventilation;
theSMNestimatesalowrisklevelgivingalowprioritytoadditionalmeasures.Themeasured
number concentration of nanoͲTiO2 is very low. The PCR8hrͲTWA <<1, the PCR15minͲTWA <1. Van
Broekhuizenetal(2012a)reportthatforthispaintmixingoperationshortͲtermhighemissions
from‘nonͲnano’paintͲcomponentsastalcandCaCO3occurinthenearfield. Workplace 3 regards the manufacturing of pigment granulates. 3a is the
manufacturingusingafumehood,butwithanopenmixingvessel.Existingmeasureswerein
both situations local exhaust ventilation and personal protective equipment: respirators and
protectiveclothing.TheGuidanceandtheCBNestimatea‘medium’risklevel,andtheSMNa
‘low’ risk level. Measurements show a PCR8hrͲTWA >1 and PCR15minͲTWA>>1 for the insufficient
controlled situation with an open mixing vessel (3a). Full coverage of the mixing vessel
(situation 3b) results in a significant emission reduction PCR8hrͲTWA <1 and PCR15minͲTWA<1. For
this fully contained situation the Guidance estimates a ‘low’ risk level, the CBN and SMN
remainatrespectivelya‘medium’and‘low’risklevel.
Workplace 4 regards the nanoͲglass breaking (4a). The activity gets a ‘medium’ risk
ranking from the Guidance and a ‘low’ risk ranking from the CBN. The glass cutting gets a
‘medium’rankingwithbothtools.TheactivitieshaveazeroͲemission:PCR8hrͲTWA<<1.TheSMN
was not applied at these activities because the authors state that the SMN should not be
appliedforabrasionandphysicalfracturingoperations.
Workplace 5 regards fluorescent tube manufacturing. The Guidance, CBN and SMN
estimatetheaddingofAl2O3inafullycoveredmixingvesselbyusinganaspirationlance(5a)at
a‘low’risklevel.Measurementsshowazeroemission(PCR15minͲTWA<<1).Furtherprocessingof
theglasstubes(5bͲj),withheatingandcombustionoperationsgeneratesahighnanoparticles’
emission(PCR>>1),presumablyofPGNPs.Theseoperationsareestimatedata‘medium’risk
level by the Guidance assuming an emission of a further undefined mix of nanoparticulate
soot.ItislikelythatPGNPsdominatethisemission,butthesecannotbeassessedwiththeCBN
and SMN. On the basis of the PCR improvement of control measures is indicated here,
althoughstrictlyspoken,thePGNPsarenotMNMsandsubjecttodifferentpolicies.
Workplace 6 regards car repair with abrasion of nanoͲenabled surfaces and spraying
operationsnanoͲenabledcoatings).Thepaintingcabinisequippedwithaventilatedwall.The
Guidance estimates all activities (6aͲd) at the ‘medium’ risk level; the SMN estimates the
141
___________________________________________________________________________________
spraying with “known” MNMs (6c) at the lowest risk level, and at the highest risk level for
spraying with “unknown” MNMs (6d). The CBN estimates a ‘medium’ risk level for abrasion
(6a)andspraying(6c)forknownMNMs,anda‘high’risklevelforabrasion(6b)andspraying
(6d)with‘unknown’MNMs.Alownanoparticles‘numberconcentrationwasmeasuredinthe
inhalationzone(PCR<1).
Workplace 7 regards exterior spraying application of selfͲcleaning coating, for which
theGuidanceestimatesa‘medium’risklevel,andtheCBNandSMNestimatea‘low’risklevel.
MeasurementsshowazeroconcentrationofMNMsintheinhalationzone.
Workplace 8 regards the outside mixing of nanoͲSiO2 in concrete for which the
Guidance estimates a ‘high’, the CBN a ‘medium’ and the SMN a ‘low’ exposure risk. The
particles’numberconcentrationintheinhalationzonewasverylow(PCR<<1).
Insum,theriskestimatesmadewiththedifferenttoolsmayvarystronglybetweendifferent
activities.Theestimatedemissionpotentialfromthe Guidanceand CBNfrequentlyleadtoa
higher estimated risk level than the estimated immission potential from the SMN. An
exception is the assessment of unknown MNMs to which the SMN applies a strict
precautionary approach by assigning these situations a ‘high’ risk level. Comparing the
estimated risk levels (figure 4) with the PCRs seems to show that risk levels (especially from
the Guidance and CBN) frequently overestimate the risks related to the emission of MNMs.
This is not necessarily the case. Existing control measures, installed at the workplaces to
control the emission of volatile substances, dust or mist may be adequate to control the
emissionofMNMsaswell.
AhighrisklevelasestablishedbyaparticularCBtooldoesnotnecessarilymeanthat
workplace control measures have to be improved, if compared with a low risk level as
established by another CB tool. The assignment of a ‘high’ or ‘medium’ risk level by the
GuidanceorCBNmayresultinsimilarmeasuresasa‘low’riskpriorityasassignedbytheSMN.
ApointofattentionremainstheemissionofPGNPs(occurringespeciallyatworkplaces
1and5,wheretheemissionofPGNPsiscontinuous)thatarenottakenintoaccountbyanyof
thethreeCBtools.
Sensitivityofresultstochoices
SelectingtherightdatatoqualifythehazardendpointsfortheCBNandSMNmaybe
confusing.Anexampleistheendpointcarcinogenicity.TiO2wasassignedbyIARC(2010)asa
2Bcarcinogen(possiblecarcinogenictohumans),whileitsREACHregistrationdossierindicates
that the substance has no classification (ECHA 2012a). Subsequently it is not clear whether
TiO2shouldbeassignedas“carcinogenic”intheCBNandtheSMNornot.AssigningthenanoͲ
TiO2with“unknown”isawayͲout,butanunsatisfactorychoice.AnotherexampleregardsZnO.
The REACH registration file suggests that lower grade ZnO should be classified in the EU as
reproduction toxic: Repr. Cat. 1A H360: May damage fertility of the unborn child (R61 May
causeharmtotheunbornchild)(ECHA2012b).Theestimationusedinthestudywasbasedon
thegeneralopinionthatZnOisnotreprotoxic.Howeverfromtheregistrationfileitisunclear
142
___________________________________________________________________________________
whetherstandardZnOandnanoͲZnO,whicharenotclassifiedassuch,shouldbeassignedas
reprotoxic.
Dustinessisanotherexampleofaparameterthatisnoteasytoassign.Theauthorsof
theSMNremarkthatatpresentthedustinessformost,ifnotall,nanopowders,isnotknown
quantitatively and decide that the highest dustiness class will be given as default for
nanopowderstocomplywiththeprecautionaryprinciple(VanDuurenͲSchuurmanetal,2012).
Nevertheless,whenusingtheSMNandtheCBN,achoicehastobemadebetweenunknown
anddifferentintensitiesofdustiness.
Toillustratethesensitivityoftheresultstothechoicesmadeastothetoolsstudied
here,workplaces1,2and3areconsideredinmoredetailastotheimpactofchoicesonthe
estimatedrisklevel.Incasesofdoubttheconsequencesofdifferentchoicesweretested.The
sensitivitywasstudiedforchoicesmadeforthehazardfactorsandexposurefactors,including
fortheSMNthepointwhethertheexistingcontrolmeasuresinfluencetheadvisedrisklevel.
Theresultsthereofaresummarizedintable4.
Table4
Sensitivity estimated risk levels generated by the tools Guidance CBN and SMN as
appliedtoworkplaces1,2and3tochoices.
Workplace
Tool
Assumptionsunderlyingthe
estimateofrisklevel
1.
Electroplating
industry
Guidance
MNM=granularandbiopersistent
Ͳ3
withadensity<6,000kgm .
Medium
ForscoringthechemicalidentityoftheMNMmakes
nodifference
CBN
MNM=unknown;hazardproperties
ofparentmaterialandNPform
“unknown”.Dustinesswasscoredas
“none”.
MNM=Cr2O3;hazardproperties
parentmaterial“yes”fordermal
hazardandasthmagen;forNPͲform
all“unknown”
MNM=unknown; unknownhazard
propertiesoftheNPform
Medium
Adviceistoupgradetheengineeringcontroltofume
hoodorlocalexhaustventilation.
Medium
IftwoendpointsofthehazardscorefortheNPͲform
wouldbescoredwith“yes”thecontrollevel
increasestothe‘high’risklevel(RL3Ͳcontainment).
High
Anyadditionalcontrolmeasuretakenresultsinalow
risklevel(risklevelIII)
MNM=Cr2O3;hazardproperties:
irritatingsubstance.
Low
Medium
High
Medium
Assigningahazardproperty“toxic”,doesnotchange
therisklevel;
SMN
2.
Manufacturing
nanoͲwallpaint
Guidance
Ͳ3
CBN
MNM=TiO2;hazardproperties
parentmaterial“no”toall(nonͲ
hazardous)andnanoͲform
“unknown”.
Dustiness:“high”
SMN
MNM=TiO2;hazardproperty
nanoform:“unknown”;
Hazardpropertynanoform:
“carcinogen”,Dustiness:“high”
143
Estimated
##
risklevel
Low
Low
Medium
Impactsofchoices
Assigningahazardproperty“carcinogen” would
increasetherisklevelto‘medium’(RLII).
nodifference
Adviceisthatupgradingoftheengineeringcontrolis
notnecessary.
Assigningahazardproperty“carcinogen”forthe
parentmaterialandthenanoformdoesnotchange
theseveritybandandrisklevel
Loweringthe“dustiness”to“medium”reducesthe
riskleveltolow(RL1)
Assigningothervaluestothedustiness(veryhigh,
mediumorunknown)doesnotchangetherisklevel.
Assigning“nocontrolmeasuresatthesource”and
“nopersonalprotectiveequipmentapplied”,does
notchangetherisklevel
Assigningothervaluestothedustiness(veryhigh,
mediumorunknown)doesnotchangetherisklevel
___________________________________________________________________________________
Workplace
Tool
Assumptionsunderlyingthe
estimateofrisklevel
3.
Manufacturing
Pigment
Concentrates
Guidance
Ͳ3
Medium
nodifference
CBN
MNM=ZnO;Hazardpropertyparent
material:“no”toall;nanoͲform:
“unknown”toall.
Medium
material:“no”toall;nanoͲform:
“unknown”toall.
Dustiness:“low”
material:“yes”toreproductive
hazard,“no”totherest
Dustiness“low”
MNM=ZnO;Hazardpropertynano
form:“unknown”
Dustiness:”high”
Low
Adviceisthatupgradingoftheengineeringcontrolis
notnecessary.
Assigning“medium”or“unknown”tothedustiness
doesnotchangetherisklevel.
Assigning“low”or“none”tothedustinessreduces
theriskleveltolow(RL1).
SMN
MNM=ZnO;Hazardpropertynano
form:“reproductiontoxic”
Dustiness:”high”
Estimated
##
risklevel
Impactsofchoices
High
Assigning“yes”toreproductivehazardfortheparent
materialofZnOdoeschangetheriskleveltohigh
(RL3)
Low
Assigningothervaluestothedustiness(toveryhigh
ormediumorlow),doesnotchangetherisklevel.
TherisklevelchangeswhenZnOwouldbeassigned
as“reprotoxic”.
Medium
#
Forthescoringofthehazardendpointsofthebulkmaterials(CMRS)thelabelingwasusedaccordingtothe
listofcarcinogenic,mutagenicandreprotoxicsubstancesoftheDutchMinistryofSocialAffairs(Staatscourant
2012),andaccordingtothelistofallergenicsubstancesaspublishedbytheDutchHealthCouncil(2008)
## Foranexplanationoftherisklevelsseelegendtable2
EstimatingrisklevelswiththeGuidancedoesnotpresentmuchofaproblem.Selectionofthe
hazardcategoryisgenerallyeasytobemade,sincetheselectionintheGuidanceislimitedto
nanoparticles’size,densityandshapeanddoesnotrequirespecifictoxicitydata.Selectingthe
exposure category seems often simple as well, although problems may arise for example in
choosing between exposure category 1 and 2, when a solid powder is mixed into a fluid by
mechanicallyaddingthepowderunderthefluidsurface,whilethemixingvesselitselfisopen.
Thenthechoiceshouldbemadewhetherthenanoparticlesarecontainedinafluidmatrixor
that exposure to nanoparticles is possible. For dispersive use of MNMs few options are
available todifferentiate.Thisquite easily leadstoarisk ranking ata ‘medium’ or ‘high’ risk
level. For these situations the Guidance advises to measure the nanoparticle’s number
concentration.
TheCBNresultsaresensitivetochangesmadeinassigningexposurefactorsandonlylimitedly
sensitivetochangesinhazardfactors.Thisisshownforexampleforworkplace2,wherenone
ofthechoicesmadeforthehazardfactorcarcinogenicity(‘yes’,‘no’or‘unknown’)influences
therisklevel,whileareductionofthedustiness(e.g.fromhightomedium)directlyleadstoa
downgrading of the estimated risk level. However, assigning in workplace 3 the parent
materialZnOas‘reproductiontoxic’leadsto‘upgrading’oftherisklevel.Thefactor‘operation
duration’ in the CBN (also important for “scoring” the exposure) may as well have a large
144
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impact on estimated risk level as can be shown with activity 4a (breaking glass) which was
estimated to be <30min/day, resulting in a low risk level (to be controlled by general
ventilation). Assigning this factor with 30Ͳ60min would shift the risk level to medium (to be
controlledbyfumehood/localexhaustventilation).
The SMN results are sensitive to changes made in assigning hazard factors and less
sensitivetochangesmadeinassigningexposurefactors.Anillustrationisworkplace2wherea
choice“unknown”forthehazardfactorresultsina‘low’risklevelandchoosing“carcinogenic”
for the hazard factor results in a ‘medium’ risk level, while none of the changes in the
dustiness (very high, medium or low) changes the risk level. For workplace 1 with unknown
MNMstheprecautionaryapproachisdominantresultingina‘high’risklevel,butaguessthat
the MNM is Cr2O3 would lead to a ‘low’ risk level for irritating MNMs or ‘medium’ for
carcinogenic, or mutagenic MNMs. Similar upgrading of the risk level is seen in workplace 3
whenZnOiswouldbeclassifiedas‘reproductiontoxic’.TheSMNresultsarenotsensitiveto
changes made in existing control measures for workplaces 2 and 3. Here local exhaust
ventilationisinplaceandhalfmaskrespiratorswithfiltersaspersonalprotectiveequipment
areused.Settingbothcontrolmeasuresat“none”doesnotincreasetherisklevel.
Insum,theapplicationoftheprecautionaryprinciple,asoperationalizedbythethreecontrol
banding tools leads easily to an advice to apply a high level of engineering control. In some
other cases the advised engineering control is higher than the existing level of control.
“Unknowns”appeartobeessentialelementsindeterminingtheadvisedlevelofengineering
control, but it depends on the sensitivity of the tool whether altering (some of) the
“unknowns” by “knowns” will change the advised engineering control. The Guidance is the
leastsensitiveto“unknowns”,butasaconsequenceitmaysuggestahigh(precautionary)risk
level,whichmaybecorrectedbycarryingoutthemeasurements,asadvisedinthistool.The
CBNresultsarerelativelysensitivetochangesmadeintheprobabilityfactors;theSMNresults
are relatively sensitive to changes made in the hazards factors. In many cases the advice
generated with the SMN corresponds with measurements of workplaces particles’ number
concentrations regarding the estimation of exposure to MNMs, although it appears highly
advisabletodevelopamethodtoquantifythefactor“dustiness”.
Discussion
Theconceptforthecontrolbandingtoolswasdevelopedtosupporttheindustrycarryingout
anacceptableriskassessmentwithoutthenecessitycarryingoutexposuremeasurements.By
adapting the tools to the properties at the nanoscale the lack of hazard data for MNMs
becomes manifest. It may take some time to adapt toxicity models to the properties of
nanomaterials to find out which toxicity endpoints are used best for hazard assessment of
nanomaterials (Dusinska et al 2012). In the meantime a precautionary approach is indicated
anddefaultsforthe“unknowns”havetobeapplied.Theoptiontoqualifylackingdataforan
endpoint with ‘unknown’ seems an unsatisfactory solution for this dilemma, when all the
requestedendpointshavetobequalifiedassuch.ButgiventherapidintroductionofMNMsin
145
___________________________________________________________________________________
products(stronglystimulatedbygovernmentalandindustrialdevelopmentalprograms)sucha
precautionaryapproachmightbeprovisionallyacceptable.Theotheroption,aschosenbythe
Guidance,avoidstheuseofthemanysofar‘unknowns’andusetheparticles’sizeandshape
astheonlyfactorstoestimatethenanospecifichazards.TheNRV,andconsequentlythePCR,
use the same approach by providing a provisional alternative for OELs. For companies and
regulators that adopt the precautionary principle these tools may be useful, but (as a
consequence) the uncertainty regarding the advised risk level remains and the advised
engineeringcontrolmeasuresmayretrospectivelyhavebeentoostrict.
In cases where uncertainty remains and an optimal choice of engineering control is
difficulttomake,monitoringofthenanoparticles’numberconcentrationandmeanparticles’
diameter (irrespective of the composition) would seem indispensable (Ramachandran et al
2011). Provisional NRVs may provide a useful tool for exposure management. Sometimes
furtherchemicalanalysisofsamplesmaybenecessary.Moreingeneralitseemsadvisableto
carry out further exposure assessments at the wide variety of workplaces where MNMs are
applied and complement this with an overview of situations where PGNPs dominate the
airborneNPsconcentrations.
Regarding the question raised: “Do different tools when applied at the same
workplaces lead to similar risk estimates and recommendations for control measures?” the
comparison of recommendations as generated by the tools shows that the risk levels
estimated (or risk priorities estimated) may vary. This may partly be explained by the
difference in concept used: an emission potential for the Guidance and the CBN, and an
immission potential for the SMN that takes existing control measures into account. The
variationinestimatedrisklevelsmayalsobeexplainedbydifferentchoicesmadeinthetools
tomaketheprecautionaryprincipleoperational.Nevertheless,theresultingriskmanagement
measuresmaybecomparable,asbeingbasedonforexampleandadvicetoselectanefficient
control measure according to the tiered OHS (the Guidance), an advice for ‘upgrading’ the
engineering control (CBN), or a risk priority with options for control (SMN). Whether the
advisedriskmanagementmeasuresareoverͲprecautious,comparedtotheactuallymeasured
nanoparticles’ number concentrations, is hard to judge taking into account the fact that the
measurements regard backgroundͲcorrected number concentrations of MNMs + PGNPs. The
threetoolsonlyassessrisksregardingMNMs.ItislikelythattheemissionofMNMs(+PGNPs)
inmostofthecasesstudiedislow,withaPCR<1(cases2,3b,4aͲb,5a,6aͲd,7and8).Assuch,
it would not have a high priority to further improve the control measures. By giving the
situationsalowriskpriority,thisconclusionisinmostcasesconfirmedbytheSMN.Onlywhen
poorly defined MNMs are used (e.g. 6d) the precautionary approach of the SMN leads to a
‘high’ risk priority and indicates to take further actions, e.g. to put more upstream effort in
obtaininginformationabouttheMNMsusedinthenanoͲenabledproduct.
It should however be noted that the dispersive uses of MNMs in the cases studied
were generally only shortͲterm activities. ShortͲterm peak exposures may be masked in an
8hoursͲTWAapproach.Theuseofa15minutesͲTWAmaygiveabetterindicationfortheshortͲ
termactivitiesandindicatewhethercontrolmeasuresshouldbeinstalledtoreduceapossible
146
___________________________________________________________________________________
peakexposure.TheGuidancedoesnotdealwithshortͲtermpeaks;theCBNandSMNconsider
activitieswithadurationofthetask<30min,butnospecificattentionispaidtopeaks.Itisnot
clearwhethershortͲtermhighpeakexposuresplayaroleinthehazardofnanoparticlesorthat
theriskisratherdeterminedbyan8hrͲTWAͲexposurelevel(vanBroekhuizenetal2012c).For
riskmanagementhoweveritseemsindicatedtooperationalizetheprecautionaryapproachby
meansofpreventingshortͲtermhighpeaks.
Regarding the question “Is it legitimate to ignore PGNPs in risk assessment and risk
management when assessing MNMs?” it should be noted that none of tools studied take
PGNPs into account in the control banding exercise. PNGPs are, however, mentioned in the
Guidance as potential source of nanoparticle exposure, and are object of the measurement
schemeprovided.ItisclearthatPGNPsmaycontributetothetotalexposuretonanoparticles
and sometimes even be dominating (e.g. the studied cases 1 and 5bͲj). In many cases the
emissionofPGNPshasacontinuousorsemiͲcontinuouscharacter,asisforexamplethecase
in heating and combustion activities (Donaldson et al 2005), and with the use of electrical
equipment (Szymczak et al 2007). It is likely that PGNPs generated by these sources are
hazardousandmaybecomparableintoxicitytotheanticipatedandprovedhazardsforMNMs
(Bérubéetal2007;SCENIHR2009,Pauretal2011).Therefore,PGNPsshouldnotbeignored
when making a risk assessment (EU/US 2012). More attention for these potential hazardous
PGNPsinregularriskassessmentsatworkplacesisindicated.ThisholdsalsoforalsononͲnano
workplaces. The Control Banding Tools should find a way to deal with this potentially
hazardoussourceofnanoparticles.
The estimates of potential health risks of the control banding tools studied can be
characterized by a high degree of uncertainty. None of them gives an explicit answer to
questions concerningthebestengineering controloptions. Nevertheless they may guidethe
downstream user of MNMs and nanoproducts in alerting them about the potential risks of
MNMsandincreasetheawarenessofemployersandemployees.
Theuseofthecontrolbandingtoolspoint clearly attheexistinggapsin information
supplythatshouldbefilledbythemanufacturerandsupplier.Inthisrespecttheyhighlightas
well some gaps in existing legislation especially regarding the transparency and reporting of
the use of MNMs in products. Where confidentiality on product composition remains an
acceptedindustrialpolicy,whilefacinganapparentlackinknowledgetoguaranteeasafeuse,
theendusershouldbeprovidedwithsolidmeanstoenforcedemandformoreinformation.A
precautionary approach is an option to cope with insufficient information, but it is highly
preferabletodesignasafeworkplacewithrobustriskinformation.TheREACHphilosophyof
the upstream shift of responsibility along the production chain to generate hazard data on
substancesandtoprovidedownstreamriskinformationshouldbeurgentlyoperationalizedfor
nanomaterialsaswell.TheidentificationofthecontributionofhazardousPGNPstothetotal
airborneconcentrationofnanoparticlesattheworkplacepointsalsoatthelackofknowledge
regarding the type of equipment emitting nanoparticles, their composition and potential
hazard. It highlights the responsibility of the original equipment manufacturer (OEM) to
generateknowledgeontheseitemsandtocommunicatethisdownstreamwiththeequipment
147
___________________________________________________________________________________
users.ItalsoraisesquestionswhetherthepotentialemissionofPGNPsshouldbemadepartof
thedesignofequipment.
Conclusion
The Guidance, the CBN and the SMN, when applied at the same workplaces, may vary in
estimating risk levels depending on whether the emission or immission potential is assessed
andduetooperationalizationoftheprecautionaryapproach.Theselectedengineeringcontrol
based on the varying risk estimates may be similar. The Guidance is strict when dispersive
MNMsareusedandnotsensitiveto“unknowns”inhazarddata.TheCBNisrelativelysensitive
tochoicesmadeinassigningtheexposurecharacteristics,whilefortheSMNthisisthecasefor
choices regarding the hazard characteristics. None of the control banding tools takes the
emission of processͲgenerated nanoparticles into account. This may lead to an
underestimation of the exposure to nanoparticles, and as a consequence to an
underestimationofthepotentialrisksat‘nano’and‘nonͲnano’workplaceswherePGNPsare
formed.
The control banding tools may have a function in increasing the awareness of
employers and employees about the possible hazards and risks of nanomaterials. The tools
makeexplicitwhatdataareurgentlyneededtofillthegapstomakeareliableriskassessment.
Acknowledgment
ThestudywascarriedoutwithagrantoftheUvAHoldingBV.TheauthorsliketothankFleur
van Broekhuizen for valuable discussions about the topic. The comments of anonymous
reviewersonanearlierversionofthisstudyaregratefullyacknowledged.
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International Workshop on Nano Reference Values
___________________________________________________________________________________
Exposure Limits for Nanoparticles: Report of an
PIETER VAN BROEKHUIZEN1*, WIM VAN VEELEN2, WILLEM-HENK
STREEKSTRA3, PAUL SCHULTE4 and LUCAS REIJNDERS5
1
IVAM UvA BV, Plantage Muidergracht 14, 1018TV Amsterdam, Netherlands; 2FNV, Amsterdam,
Netherlands; 3VNO/NCW, The Hague, Netherlands; 4NIOSH, Cincinnati, OH 45226, USA; 5University
of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics, Amsterdam, Netherlands
Received 30 March 2012; in final form 16 April 2012
This article summarizes the outcome of the discussions at the international workshop on nano
reference values (NRVs), which was organized by the Dutch trade unions and employers’
organizations and hosted by the Social Economic Council in The Hague in September 2011. It
reflects the discussions of 80 international participants representing small- and medium-size
enterprises (SMEs), large companies, trade unions, governmental authorities, research institutions, and non-governmental organizations (NGOs) from many European countries, USA,
India, and Brazil. Issues that were discussed concerned the usefulness and acceptability of precaution-based NRVs as a substitute for health-based occupational exposure limits (OELs) and
derived no-effect levels (DNELs) for manufactured nanoparticles (NPs). Topics concerned the
metrics for measuring NPs, the combined exposure to manufactured nanomaterials (MNMs)
and process-generated NPs, the use of the precautionary principle, the lack of information
about the presence of nanomaterials, and the appropriateness of soft regulation for exposure
control. The workshop concluded that the NRV, as an 8-h time-weighted average, is a comprehensible and useful instrument for risk management of professional use of MNMs with a
dispersible character. The question remains whether NRVs, as advised for risk management by
the Dutch employers’ organization and trade unions, should be under soft regulation or that a
more binding regulation is preferable.
Keywords: derived no-effect levels; nano reference values; occupational exposure limits; precautionary principle;
risk management
INTRODUCTION
The increasing production and use of manufactured
nanomaterials (MNMs) has given rise to initiatives
of governmental authorities, industrial organizations, and civil society organizations to advocate the
application of the precautionary principle for risk
management (EC, 2000). The tools chosen to make
this principle operational for the workplace differ
in approach, but they have in common that they all
aim to minimize the occupational exposure as far
*Author to whom correspondence should be addressed.
Tel: +31-20-525-6324; fax: +31-20-525-5850
email: pvbroekhuizen@ivam.uva.nl
as reasonably achievable. Control banding is an
approach that is gaining growing acceptance among
risk assessors. Several control-banding tools have
been published, all making use of a two-dimensional
matrix, generally combining a qualitative assessment of hazardous properties of the used nanomaterials with an estimate of the likeliness of inhalatory
exposure (Paik et al., 2008; Schulte et al., 2008;
ANSES, 2010; Höck et al., 2011; Hansen et al., 2011;
van Duuren-Stuurman et al., 2012). There are also
guidances that combine control banding in a risk
assessment tool (Cornelissen et al., 2011). In the
conventional quantitative approach to risk management of substances, health-based recommended
occupational exposure limits (HBR-OELs) are accepted
155
___________________________________________________________________________________
to determine maximum levels of exposure (SCOEL,
2009). In analogy the European legislation REACH
requires that manufacturers derive a derived noeffect level (DNEL) for the substances they bring to
the market (ECHA, 2010). DNELs may be used to
establish acceptable exposure limits.
The ‘new’ properties of nanomaterials, incomplete
information about the hazards of nanomaterials,
their varying size distribution, and heterogeneous
composition complicate application of the conventional approach for the derivation of limit values for
nanomaterials (based on agreed toxicity test systems
and safety factors). It has been suggested that a more
generic approach might be more appropriate to generate acceptable exposure limits for groups of nanomaterials (Schulte et al., 2010).
In line with this suggestion, and as a means to
make the precautionary principle operational for the
use of nanomaterials at the workplace, the Dutch
employers’ organization and trade unions advised
developing the concept of nano reference values
(NRVs) (SER, 2009). For this purpose, they further
developed the benchmark level approach as suggested by the German Institut für Arbeitsschutz (IFA,
2009) and tested its comprehensibility and suitability
for use at the workplace in a pilot project with companies applying MNMs.
The findings of the Dutch employers’ organization
and trade unions were presented and discussed in an
international workshop at The Hague in September
2011 for an audience of experts and academia, workers’ and employers’ organizations, large industries
and small- and medium-size enterprises (SMEs),
non-governmental organizations (NGOs), and governmental authorities. A total of 80 participants from
the Netherlands, Germany, Austria, France, UK, Ireland, Belgium, Luxembourg, Finland, Norway, USA,
India, and Brazil took part in the discussions.
Chaired by Frank Barry from the Irish trade
unions, introductory presentations were given by
representatives from the Dutch trade union (FNV),
W.v.V., and employers’ organization (VNO/NCW),
W.-H.S., explaining their positions towards safe
working with nanomaterials. P.v.B. (IVAM UvA) and
Bärbel Dorbeck-Jung (University of Twente) illustrated the findings of the pilot project on NRVs. Input
from industries participating in the pilot project was
given by Jolien Stevels (Holland Colours) and Robert Beckers (NanoCoatings) who clarified how in
their company they make a precautionary approach
operational. Markus Berges (IFA, DE) explained
the basis for the derivation of the German guidance
values for nanomaterials. P.S. [National Institute for
Occupational Safety and Health (NIOSH), USA]
156
elaborated on the NIOSH approach to standard setting for nanomaterials and illuminated the state of
the art of OELs for nanomaterials. John Cherrie
(Institute of Occupational Medicine, UK) finally
explained how the UK manages potential risks
from nanomaterials. A panel discussion chaired by
L.R. (UvA, NL) with some of the speakers mentioned previously, Jorge Costa-David (European
Commission, DG Employment) and Dirk van Well
[Dutch Association of the Chemical Industries
(VNCI)], focused on the definition of nanomaterials, the preferred metrics, and the appropriateness
of applying limits to short-term peak exposures for
nanoparticles (NPs). They also discussed the use
of the precautionary principle for standard setting,
the information about the presence of nanomaterials, the choice for voluntary initiatives (soft regulation) versus hard regulation, and the advisability to
use NRVs. This article describes the results of this
workshop.
WORKSHOP ACHIEVEMENTS
Introductions
Health-based approach. There are agreed protocols
to identify a threshold above which an adverse health
effect may occur (SCOEL, 2009; ECHA, 2010). For
substances with such a threshold, health-based occupational Exposure Limits (OELs) or DNELs may
be derived. For substances without an identifiable
threshold level, as is the case for genotoxic carcinogenic substances and some allergenic substances, a
risk-based approach defining a level that allows for a
certain risk may be used. The Netherlands accepted,
for example, a target level for one worker to develop
a cancer in a population of 106 (million) workers per
year (incident 10−6) or one worker to get sensitized
in a population of 100 workers per year, related to
the exposure to the specific substance. For a few
frequently used MNMs, exercises have been carried
out to derive a health-based OEL or DNEL. Stone
et al. (2010) derived provisional DNELs for some
frequently used nanomaterials by using the methodology as described by REACH. P.S. illustrated
the preference of NIOSH for health-based limit
values by explaining the efforts to derive a recommended exposure limit (REL) for carbon nanotubes
(CNTs) (NIOSH, 2010) and titanium dioxide (TiO2)
(NIOSH, 2011) (see Table 1). He stated that the
NIOSH approach to TiO2 is supported by the finding that the toxicity seems not to be significantly
modified by the crystal structure (anatase or rutile)
or the coating on the particle, which indicates that
___________________________________________________________________________________
Table 1. Proposals for OELs and DNELs for specific NPs
OEL or REL (mg m−3)
Substance
MWCNT (Baytubes)
MWCNT (10–20 nm/5–15 μm)
Scenario NOAEC pulmonary effects
MWCNT (10–20 nm/5–15 μm)
Scenario LOAEC immune effects
MWCNT (Nanocyl)
CNT (SWCNT and MWCNT)
Fullerenes
Fullerene
Ag (18–19 nm)
TiO2 (21 nm)
TiO2 (10–100 nm; REL)
TiO2 P25 (primary size 21 nm)
8-h TWA
Short-term inhalation
0.05
201
Chronic inhalation
Chronic inhalation
8-h TWA
8-h TWA
Chronic inhalation
DNEL (mg m−3) References
33.5
4
0.67
0.0025
0.007
44.4
0.27
~0.8
DNEL-lung scenario 1
DNEL-lung scenario 2
DNEL-liver
Chronic inhalation
10 h day−1, 40 h week−1
TWA 8 h day−1, 5 day
week−1
0.33
0.098
0.67
17
0.3
1.2
Pauluhn (2010)
Stone et al. (2010)
Stone et al. (2010)
Stone et al. (2010)
Stone et al. (2010)
Nanocyl (2009)
NIOSH (2010)
Stone et al. (2010)
Stone et al. (2010)
NEDO-2 (2009)
Stone et al. (2010)
Stone et al. (2010)
Stone et al. (2010)
Stone et al. (2010)
NIOSH (2011)
NEDO-1 (2009)
SWCNT, single-wall CNT; MWCNT, multi-wall CNT; NOAEC, no-observed adverse effect concentration; LOAEC, lowest
observed adverse effect concentration.
the particle surface area of nano-TiO2 seems to be
the dominating factor in toxicity. This facilitates the
use of the NIOSH REL for nano-TiO2 since further
characterization of the ‘form’ of the nano-TiO2 for
risk assessment could be limited. For CNTs, NIOSH
found that a working lifetime exposure of 0.2–2 μg
m−3 [8-h time-weighted average (TWA)] would suffice to avoid health effects, but that the measurability, the relatively high upper limit of quantization,
determined their proposal for the REL of 7 μg m−3.
Table 1 summarizes these attempts to derive a massbased OEL or DNEL for MNMs. The table shows
quite large differences for CNTs with ‘similar’ identity (but possibly differing in specific properties).
The large amount of toxicity testing and data needed
for deriving an OEL for single MNMs is recognized
by P.S., and he suggests a more broadly useable
approach to derive health standards for groups of
nanomaterials that have a similar molecular identity
(e.g. CNTs, metal oxides, and metals) or to group
together nanomaterials that share a common mode of
action (for example, the formation of reactive oxygen species) (Schulte et al., 2010). A generic massbased approach was published by Pauluhn (2011),
suggesting to derive a DNEL for MNMs based on
the ‘overload hypothesis’, stating that the particle
displacement volume is the critical effect for lung
toxicity.
Pragmatic approach. MNMs are often characterized by large deficiencies in hazard data, and thus
safe exposure levels cannot be determined (Schulte
et al., 2010). There is growing evidence that the surface of the NPs seems an important trigger for the
toxic effect (Abbott and Maynard 2010; Aschberger
and Christensen, 2011, Ramachandran et al., 2011),
which indicates that the particles’ number concentration seems to be a better metric for potential risks
than the conventionally used mass-based approach.
When there are large deficiencies in hazard data,
NIOSH cites the use of qualitative control-banding
methodologies for which several suggestions have
been made (see Introduction) as an alternative for the
OEL/REL approach for MNMs. This is also in line
with the preferred approach in the UK as explained
by Cherrie. He reflected on the approach of the British Standard Institute (BSI), who as a forerunner
of the NRVs developed the idea of guidance values
for nanomaterials, derived from existing OELs for
coarse materials (BSI, 2007). This BSI approach
was opposed by the HSE working group on action
to control chemicals (WATCH) because in its opinion the meaning of benchmark exposure levels and
their regulatory significance could be easily misinterpreted. WATCH prefers the gathering of exposure
measurements for MNMs and focusing on principles
of good control practices.
157
___________________________________________________________________________________
Table 2. NP number concentration for a mass concentration of 0.1 mg m−3
Name
CNT, commercial product
Polystyrene
CNT
Fullerene (C60)
Typical respirable dust
Titanium dioxide
Zinc oxide
Cerium oxide
Iron
Silver
Gold
Density (kg m−³)
110
1050
1350
1650
2500
4240
5610
7300
7874
10 490
19 320
NP (cm−3)
d = 20 nm
d = 50 nm
d = 100 nm
d = 200 nm
217 029 468
22 736 420
17 683 883
14 468 631
9 549 297
5 630 481
4 255 480
3 270 307
3 031 908
2 275 809
1 235 400
13 889 886
1 455 131
1 131 768
925 992
611 155
360 351
272 351
209 300
194 042
145 652
79 083
1 736 236
181 891
141 471
115 749
76 394
45 044
34 044
26 162
24 255
18 206
9885
217 029
22 736
17 684
14 469
9549
5630
4255
3270
3032
2276
1236
Berges explained the pragmatic approach that
was developed by IFA, the German Institut für
Arbeitsschutz der Deutschen Gesetzlichen Unfallversicherung (IFA, 2009), to derive particle number–based benchmark levels for four groups of
nanomaterials. IFA used size, form, biopersistence,
and density as parameters to distinguish the groups.
For the granular nanomaterials its aim was to establish a number-based benchmark with a mass concentration of maximum 0.1 mg m−3. On the basis of the
assumption that the granular particles have a spherelike shape, for particles of different diameters, IFA
calculated the number of particles per cubic centimetre that correspond to this mass concentration (see
Table 2).
IFA divided the granular nanomaterials into two
groups, one with a density >6000 kg m−3 and the
other with a density <6000 kg m−3, and established
benchmark levels for these groups as 20 000 and
40 000 particles cm−3, respectively. From a massbased point of view this means that for smaller nanomaterials the benchmark level for granular materials
is stricter. For CNTs, IFA took the precautionary
stand that for those CNTs that possibly exhibit
asbestos-like effects, the use of the asbestos OEL as
a benchmark level might be appropriate. At present,
however, monitoring of the above value in plants is
hampered by a lack of collection methods of verified suitability, corresponding analysis methods, and
criteria for counting the fibres and determining the
fibre count concentration. For soluble and non-biopersistent NPs a benchmark was assigned according
to the applicable OEL for the coarse (or molecular)
form because regarding hazard, these particles are
supposed to behave like ‘conventional’ substances.
Application of the precautionary principle in the
Netherlands. As explained by W.-H.S. and W.v.V.,
158
the Dutch employers’ organization and trade unions
have developed NRVs, building on the work of IFA.
They acknowledge that when reliable data are missing and uncertainty prevails other tools are necessary
to allow industry to use nanomaterials and to make
acceptable risk assessment. W.-H.S. and W.v.V. advocate that alternative tools must be practical but transparent and trustworthy as well. This calls for close
cooperation of workers’ and employers’ organizations on these matters, as was realized in the joint
advice for safe working with nanomaterials at the
workplace (SER, 2009). This cooperation has led to
the derivation of NRVs, which provides the employer
with a provisional limit value when airborne NPs
may be generated at the workplace.
The IFA-benchmark levels were evaluated in the
Netherlands by a group of experts (Dekkers and
de Heer, 2010) and further developed by a coalition of trade unions and employers’ organizations in
the pilot NRV (van Broekhuizen et al., 2011, 2012;
P. van Broekhuizen and B. Dorbeck-Jung, in preparation). The NRVs were made part of the precautionary approach as developed in the advice of the Social
Economic Council (SER, 2009). The following
scheme for recommended NRVs (as 8-h TWA) was
adopted (SER, 2012) (see Table 3).
NRVs are established as provisional limit values
that are to be replaced by HBR-OELs or DNELs
as soon as these become available for the specific
NPs or for groups of NPs. NRVs are intended to be
a warning level: when they are exceeded, exposure
control measures should be taken. They are defined
for MNMs as a background corrected 8-h TWA
exposure level. With reference to the Dutch Labour
Conditions Act, the Dutch Government states that
they regard the provisional NRVs as the best available science and state-of-the art approach for risk
___________________________________________________________________________________
Table 3. NRVs for four classes of MNMs
Class
1
2
3
4
Description
Rigid, biopersistent nanofibres for
which effects similar to those of
asbestos are not excluded
Biopersistent granular
nanomaterials in the range of
1–100 nm
Biopersistent granular and fibre
form nanomaterials in the range
of 1–100 nm
Non-biopersistent granular
nanomaterials in the range of
1–100 nm
Density
NRV (8-h TWA)
−3
—
0.01 fibres cm
>6000 kg m−3
20 000 particles cm−3
<6000 kg m−3
40 000 particles cm−3
—
Applicable OEL
Examples
SWCNT or MWCNT or metal oxide
fibres for which asbestos-like effects
are not excluded
Ag, Au, CeO2, CoO, Fe, FexOy, La, Pb,
Sb2O5, SnO2
Al2O3, SiO2, TiN, TiO2, ZnO,
nanoclayCarbon black, C60,
dendrimers, polystyreneNanofibres
with excluded asbestos-like effects
e.g. Fats, NaCl
SWCNT, single-wall CNT; MWCNT, multi-wall CNT.
assessment of nanomaterials (Atsma, 2009; Donner,
2010).
FORUM DISCUSSION
The introductory presentations were followed by
a general discussion between the forum (with participation of van Well, P.v.B., P.S., Costa-David,
and Cherrie chaired by L.R.) and the audience. The
forum accepted the metric based on particles per
cubic centimetre for the NRVs. With regard to the
setting of a limit value for nanotubes in general, the
forum welcomed the suggestion not to limit the first
group of NRV scheme to CNTs only but to extend
this group to all rigid biopersistent fibres in general.
This choice reflects better the analogy of nanotubes
with asbestos-like behaviour. P.S. indicated that this
is a precautionary approach, but it may be difficult
to count fibrous MNMs in ‘bird-nest’ agglomerates.
With regard to the definition of the size of nanomaterials in the NRV concept, there was agreement in
the workshop that workplace risk assessment of NPs
should take into account particles and agglomerates
with a diameter >100 nm as well. Setting boundaries
to the diameter of nanomaterials was argued to be
preferentially practical, leading to a suggestion to
take an upper limit of ~300 nm into account. This
limit cannot be substantiated by scientific arguments
favouring a cut-off point for ‘nanohazard’ [as was
also discussed by Lidén (2011)], but practical arguments, e.g. existing upper detection limits of available measurement equipment were used. The physical
transport behaviour in air was brought forward as
an argument not to establish a limit >200 nm. The
recommendation of the European Commission (EC,
2011), aiming to set a clear definition for nanomaterials for legislative purposes, sets the upper diameter
limit for nanomaterials at 100 nm (for 50% of the
particles in the material). The EC emphasizes that
there is no scientific evidence to support the appropriateness of this value in view of hazard and that
the use of a single upper limit value might be too
limiting for the classification of nanomaterials and
a differentiated approach might be more appropriate. The choice to bring the concept of NRV scheme
(see Table 3) in line with the European definition
for nanomaterials must be seen against this background. In practical situations, ‘larger’ structures
(agglomerates and aggregates) of primary particles
of <100 nm may have to be taken into account for
risk assessment.
With regard to the idea to set, in addition to the 8-h
TWA, a standard for short-term peak exposures to
nanomaterials, the forum almost unanimously took
a critical stand. P.S. pointed at spikes that may occur
while opening a reactor vessel and stated that these incidents should not be ignored in risk assessment. But he
emphasized that this does not legitimize the development of a separate standard for these short-term peaks.
Berges also criticized the idea, based on the fact that
effects of short-term peaks for particulate exposure
cannot be substantiated by toxicological knowledge. A
toxicologist from the audience reflected at the slow processes in the lung so as to argue not to take peaks into
account in the assessment of risks by NPs. L.R., in contrast, reflected on the evidence that short-term peaks of
ultrafine particles in ambient air could be associated
with cardiovascular effects. The panel agreed to dismiss
the approach as proposed for momentary peaks (lasting
only a few seconds): NRVpeak=10 × NRV8-h TWA. On the
other hand, the proposal to use the ‘rule of thumb’ as
used in chemical risk assessment for exposure to NPs
over a 15-min TWA period, NRV15-min TWA = 2 × NRV8-h
TWA, found considerable support in the forum. For risk
management a NRV over a 15-min period seems a useful tool as argued by Berges and van Well.
159
___________________________________________________________________________________
Measurement in the workplace
Correct for background
& calculate 8 -hr TWA
COMPLIES WITH NRV
< NRV
No further characterizaon required
> NRV
Yes
Disncon with measurement
strategy possible
Concentraon manufactured
NPs < NRV ?
Disnguish manufactured
NPs from PGNP with
measurement strategy
Disncon with measurement
strategy not possible
No
UNCERTAIN COMPLIANCE WITH NRV
Further chemical/physical characterizaon of
NP advisable
DOES NOT COMPLY WITH NRV
Risk management measures required
Fig. 1. Traffic light scheme for characterizing NPs and use of NRVs (in colour in the online edition).
Process-generated NPs
A complication for measurement of NPs at workplaces is that electrical machines and heating and
combustion processes may generate process-generated NPs (PGNPs) that may contribute substantially
to the nanoparticulate pollution in the workplace
air. Additionally, certain conventional compounds
used at some workplaces may contain as well a
nanoparticulate fraction that may contribute to the
total concentration of NPs in the workplace air (van
Broekhuizen et al., 2012). PGNP adds to the total
exposure to NPs (Donaldson et al., 2005; BéruBé
et al., 2007; Evans et al., 2008; van Broekhuizen et
al., 2012). It is likely that PGNPs will agglomerate
with airborne MNMs, making the ‘simple’ use of
NP-specific OELs (when available) questionable.
A strategic scheme for comparing measured workplace NP concentrations with the NRVs is presented
in Fig. 1.
160
The need to prevent the formation and emission of
PGNPs was recognized as an issue of high importance by the forum. Although the formation of
PGNPs is well known from welding and from diesel
exhaust particulates, formation by other common
sources (such as electromotors) has so far often
escaped the attention of risk assessors. Costa-David
from the EC and Berges from IFA stated that PGNP
preferably needs a separate policy approach and
emphasized that they should not be mixed up in
handling MNMs. They emphasized that the choice
to consider both sources in a combined approach is
a political one. Cherrie and P.v.B. argued that the
choice to take both sources, PGNPs and MNMs,
into consideration is a correct one in dealing with
potential hazards. This approach would also simplify a practical assessment.
It was emphasized that harmonization of measurement strategies for exposure to MNMs is a topic
___________________________________________________________________________________
of high priority. Initiatives were discussed earlier in
the workshop on harmonization strategies to measure and analyse exposure to (manufactured) nanoobjects in the workplace air (Brouwer et al., 2012).
Precautionary principle
The importance of using the precautionary principle within the frame of MNMs, with limited hazard
and exposure data and uncertain risks, was emphasized by all speakers. Speakers for the employers’
organizations explained their leading policy principle: a minimization of all exposures to airborne
MNMs and as such for the industry to adopt a proactive attitude and also to take care of a transparent
communication on the use of MNMs. Both the Dutch
trade unions and employers’ organizations emphasized the need for pragmatism in risk management
and recognized the fact that precaution means that
policy measures must be comprehensible and easy
to use for the users of MNMs and nano-functionalized products. It is their opinion that where possible
the exposure control measures must be scientifically underpinned, preferably health based. But they
acknowledge that waiting for OELs or DNELs until
enough evidence is available is not the appropriate
way and that they themselves have the responsibility to bring the precautionary approach into practice.
However, the ideas on how to make the precautionary principle operational for the workplace vary
widely. Trade union groups from France and the UK,
for example, take the stand that uncertainty concerning hazard of nanomaterials unambiguously leads
to a policy focused on zero exposure. According to
these trade unions exposure higher than zero is unacceptable, and so is the NRV approach because a low
exposure is accepted. Substitution should be leading,
which in case of the use of nanomaterials could be,
for example, the selection of materials with a coating
of low toxicity, functionalized to avoid the dustiness,
or applied in a non-dispersive matrix. P.S. made a
critical note by stating that although we know little
about the actual toxicity of nanomaterials, we know
quite well how to control exposure. And knowing
this we must question ourselves what risks we are
willing to take, given the benefits the materials may
bring. What we clearly do not want according to P.S.
is to lay the burden on the shoulders of the workers.
And as Costa-David added, precaution is not identical to prevention. Precautionary action is indicated
where risks are unknown but likely, whereas prevention is indicated where risks can be qualified and
quantified and as a consequence focused measures
can be designed.
Attitudes towards NRVs
As pointed out by P.v.B. and Dorbeck-Jung, one
of the findings of the pilot NRV (van Broekhuizen et
al., 2012; P. van Broekhuizen and B. Dorbeck-Jung,
in preparation) is that Dutch professional users of
MNMs involved in the pilot NRV take a proactive
stance and accept to use NRVs based on the perception of usefulness, motivated by the idea that these
provide certainty, create trust among workers, and
may forestall overregulation. Some doubts and disengagement were ventilated by one of the companies
as well about the necessity to use NRVs, especially
when exposures to MNMs are shown to be very low.
With regard to the ability to use NRVs in practice,
it was shown in the pilot NRV that the NRV concept
is comprehensible, but it is questionable whether
companies always have the right understanding of
how to relate NRVs to the MNMs, the background
concentrations, and the PGNPs at the workplace.
The need to carry out (or to commission) workplace
measurements is experienced as a burden, especially
regarding the costs to be made. The results of workplace measurements of concentrations of airborne
NPs, as carried out in the pilot NRV and presented
in the workshop, did show that the concentration of
MNMs is generally low, and that conventional fine
dust control measures taken at the workplace are
generally efficient to control MNMs compared with
the advised NRVs (van Broekhuizen et al., 2012).
The pilot NRV showed as well that use of NRVs in
risk assessment was not restrictive for most of the
assessed workplaces. But, as stated by the social
partners as well as by the company representatives,
recognition of the NRVs by governmental institutions, especially by the labour inspectorate, will
stimulate their use in practice.
Lack of information
The lack of information on the presence of MNMs
in products and their possible release during use at
the workplace was brought up by the audience as an
important issue relating to risk management. The
first step in risk assessment is to get information
about the type of nanomaterials to which exposure
is possible. In spite of some good intentions from the
manufacturing industry to supply required information, much of the information is lost along the production chain, resulting in largely uninformed end
users. According to P.S., this limits the usability of
NRVs (because some users may be simply unaware
whether they actually use or are exposed to MNMs).
P.S. argued in favour of a broad activity to develop
‘good practices’ in which exposure measurements
161
___________________________________________________________________________________
show acceptable working situations. Comprehensible guidance documents, to guide the safe working
with nanomaterials, are thought to be useful tools
as well to support SMEs and workers in risk management. Quite a number of guidance documents
on safe working with nanomaterials have been published (Paik et al., 2008; Schulte et al., 2008; Höck
et al., 2011; ANSES, 2010; Cornelissen et al., 2011;
van Duuren-Stuurman et al. 2012). Reference was
also made to the SDS (safety data sheet) of products
along which line more information on nanomaterials
in products might come available. It is foreseen that
a new adaptation of the SDS format, with respect to
the reporting of some NP-specific data, will provide
more information about nanomaterials used in the
product (ECHA, 2011).
Soft or hard regulation?
A critical remark from the audience pointed at the
experience of trade unions that guidance documents
may be readily available in practice, but that these are
generally poorly used. For ‘nano’ their expectance is
not much better. This view has been confirmed by
Engeman et al. (2012) in a study of company practices in 14 countries worldwide. Engeman et al.
(2012) identified a lack of information as an impediment to implement nano-specific health and safety
practices and found that companies were not taking
advantage of widely available government guidance
documents. The neglect of guidance documents was
argued to call for more awareness of users of nanomaterials and an enhanced activity of enforcement
authorities (like the labour inspectorate) to enforce
the use of legal instruments. Dorbeck-Jung stated
that there is a legal obligation for manufacturers and
suppliers to provide proper health and safety tools
but that the development of precautionary guidance
tools, like the NRV, so far is considered to fall within
the domain of soft law. It is, therefore, questionable
whether their use can be enforced within existing
legislation that does not recognize the notion of precaution as a basis of risk management. This shifts
the initiative to the social partners, trade unions, and
employers’ organizations to take the responsibility to
put this issue on the political agenda. Here, however,
the trade unions’ preference for binding legislation
meets the preference of employers’ organizations for
a soft law approach. Costa-David suggested that the
NRV could be referred to in the ongoing initiative
of DG Employment that studies the extent to which
OHS legislation gives, and should give explicit,
attention to nanomaterials, and also in the European
guidance for safe working with nanomaterials.
162
CONCLUSIONS
The precautionary NRV is thought to be a comprehensible and useful risk management tool as
long as health-based OELs for MNMs are not available. Other sources at the workplace may generate
(non-manufactured) NPs as well, and these may
complicate exposure control measurement. An
appropriate measurement protocol should be used
to distinguish the MNMs from the PGNPs. It is
advisable to develop a policy approach for these
PGNPs as well.
A strong political support to actively use the NRV
is essential. The deliberative setting of the Dutch
SER where employers’ organizations discuss occupational health issues with trade unions proofed to be
a successful structure to provisionally repair the gap
in the standard setting for MNMs. A broader awareness-raising campaign to explain the benefits of this
tool for risk management may help further acceptance. Governmental acknowledgement should especially be reflected in the recognition of the labour
inspectorate of NRVs as a provisional risk management tool.
EPILOGUE
Motivated by the positive outcome of this international workshop, the Dutch SER formulated its
advice to the Dutch Minister of Social Affairs in
March 2012 to accept the NRV as a provisional
risk management tool for MNMs at the workplace.
It advised to set up an active awareness campaign
to draw attention to this tool and to actively stimulate the use of NRVs by companies. The SER also
advised the minister to examine whether it is possible to develop a generic health-based OEL for
PGNPs (SER, 2012).
FUNDING
The workshop was held within the frame of the pilot project
‘“NRVNano Reference Values’”, commissioned by the Dutch
social partners FNV, CNV, and VNO/NCW with a grant from
the Ministry of Social Affairs. Further elaboration of the
results was made possible by a grant of the UvA Holding BV.
Acknowledgements—The authors like to thank the speakers,
the members of the forum, and the participants in the audience
for their valuable contributions to the discussions and results of
the workshop. The authors like to thank Fleur van Broekhuizen
for the transcripts made during the workshop.
Disclaimer—The opinions in this article are those of the
authors and speakers and do not necessarily represent the
views of the NIOSH.
___________________________________________________________________________________
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Chapter8
Conclusions
165
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166
Conclusions
Chapter 8 Conclusions T his thesis deals with two issues regarding the responsible development of nanotechnologies. The first issue concerns the precautionary principle: how should this principle be applied to the manufacture, processing and use of nanomaterials. The focus is on the positioning of stakeholders involved in this deliberative process about application of the precautionary principle, especially on the demands of environmental NGOs and trade unions (Civil Society Organizations – CSOs). These demands regard the way that industry and government should deal with nanomaterials given the lack of sufficient hazard and risk data. This thesis also deals with the attitude of the industries, which use nanomaterials, especially of small and medium sized enterprises (SME), regarding their understanding of the precautionary principle and their willingness to make the principle operational for a safe workplace. The second issue regards the operationalization of the precautionary principle and how to embed this in a risk management strategy for the workplace. The focus is on nano reference values (NRVs), which were proposed to be used as a provisional alternative for the so far lacking health‐based occupational exposure limits (HB‐OEL). So far HB‐OELs are not available for nanomaterials. The concept of NRVs was further developed to a level that might make them acceptable as a tool for risk management when uncertainty regarding hazard and risk data prevails. NRVs were applied at workplaces where manufactured nanomaterials (MNMs) and nano‐enabled products were used. The NRV‐concept was also compared with other concepts to support occupational risk management such as the control‐banding approach. Chapter 2 of this thesis deals with the role of the CSOs in the debate on the responsible development of nanotechnologies and what they propose to make the precautionary principle operational. The positions developed by trade unions and environmental NGOs show large similarities. The trade unions positioned themselves collectively under the umbrella of the European Trade Union Confederation (ETUC) with a resolution on nanotechnologies and nanomaterials in 2008 and 2010 (ETUC 2008, ETUC 2010). The Environmental NGOs formulated their position in the EEB position paper (EEB 2009). A key point in the position statements of CSOs is the demand for openness and transparency by industry about manufactured nanomaterials (MNMs) applied in products. The CSOs ask for a full life cycle analysis regarding release of MNMs in all stages of the nano‐enabled products’ life cycle and an assessment of the associated environmental and occupational health risks. The CSOs emphasize that the precautionary principle should be applied when using MNMs and nano‐enabled products for which knowledge on the health hazards is insufficient or ambiguous and risks cannot be properly assessed. As viewed by the CSOs, the application of the precautionary principle does not only relate to industry and its environmental and health & safety policy but regards also the task of governmental authorities to provide a (legal) frame that guarantees the safe use of MNMs. The CSOs’ demands are summarized in “building blocks for a precautionary approach” (see table 1). 167 NanoMatters - Building Blocks for a Precautionary Approach
__________________________________________________________________________________
Table1 Buildingblocksforaprecautionaryapproach
1.
2.
3.
4.
5.
6.
7.
NodataÆnoexposureandnodataÆ noemission.
Reportingofthecontentandtypeofnanomaterialsinproducts(traceability)
Registrationofworkerspossiblyexposedtonanomaterials
Transparentcommunicationaboutknownandunknownrisks
Derivationofworkplaceexposurelimits
Developmentofanearlywarningsystem
PreͲmarketing approval for all applications and nanotechnologies and nanomaterials as a
centralelementofthepolicyandregulatoryframework
The building blocks mentioned in Table 1 play a role in (ongoing) European initiatives to
create openness and transparency and to assure the safe use of nanoͲenabled products.
AmongthesearethepublicationsofCodesofConduct(CoC)bytheEuropeanCommission
and some large companies manufacturing nanomaterials, adaptations in the REACH
regulation to fit nanomaterials in the regulatory system, the recommendation of a
definition of nanomaterials by the European Commission, the French initiative to make
reportingoftheusenanomaterialsinproductsmandatory,initiativesinMemberStatesto
setupadatabaseofnanoͲenabledproductsatthemarketandmanyothers.Thefirstsix
buildingblocksalsoarethebasisfortheadviceoftheDutchSocialandEconomicCouncil
(SER 2009) on the safe use of nanomaterials and provide a frame for the Dutch
governmentalenvironmentalandoccupationalhealthandsafety(OHS)policy.
IndustrialopennessandtransparencyaboutMNMsusedinmarketedproductsappearsto
be problematic. The studies presented in this thesis about the construction industry, the
furniture industry and paint value chain (chapter 3) show that market penetration of
MNMs in products was limited and that awareness of the majority of the endͲusers,
employersandemployeesofthebuildingandfurnitureindustryparticipatinginthestudies
abouttheavailabilityofnanoͲenabledproductsandabouttheiractualuseappearstobe
verylow.Formostoftheparticipantsitappearedtobeverydifficulttofindoutwhether
manufacturednanomaterialsareappliedintheproductstheyuse,thereismuchignorance
ontheavailabilityofnanoͲenabledproductsatthe marketandabout theidentityof the
nanomaterialsusedintheseproducts.Thisappearstobeevenworseforsectorsthatare
activeincleaningandmaintenance.Anexampleisthesectorofcarrepair.Carrepairshops
are generally not informed about nanomaterials used in car components as coatings,
bumpers, rubber particles etc. The transparency of the nanomaterials use is further
obscured by the tendency of downstream product manufacturers to keep R&D activities
confidential that they carry out with nanomaterials to improve the performance of their
products.AndwhendownstreamproductmanufacturersareusingnanoͲenabledproducts
intheirprocessesandproductsmanyofthemarereluctanttomakethispublicastoavoid
acriticalreactionfromthepublicduetotheworldwidesocialdebateonhealthandsafety
issuesandrelateduncertainties.
Also information about hazards and risks of MNMs is poorly developed. A collective
industrial effort to generate as yet lacking toxicity data for nanomaterials and the
exchange of data bears similarities to those for chemical substances under REACH, for
168
Conclusions
__________________________________________________________________________________
which a mandatory participation was foreseen in substance information exchange fora
(SIEF) to assure and stimulate the exchange of industrially “owned” toxicity data (REACH
2006). For nanomaterials such initiatives were not identified. Only for a few
nanoparticulate substances, such as CNTs, TiO2 and Ag more detailed information,
includingproposalsforhealthͲbasedlimitvalueshavebeenprovided.Withtheexception
ofCNTs(wheresomeindustrialcompaniesprovidedproposalsforanOEL)thisinformation
was largely provided by research institutes. The limited information supply about hazard
and risks is not only a problem for CSOs and consumers, but also for downstream
professional users of nanoͲenabled products. They are held ignorant to a large extent
abouthazardsandrisksofMNMsusedintheproductssupplied,neitheraretheyinformed
bytheirsupplieraboutgapsinknowledgeabouthazardsandrisksorwhattheyshoulddo
toavoidrisksorhowtoapplyaprecautionaryapproach.
Thenodata,noexposureprinciple(buildingblock1intable1)callsupontheindustryto
applyeffectivecontrolmeasures.ItallowstheuseofMNMsinproducts,butdemandsfor
aprecautionaryapproachinoccupationalsettingstofullycontrolallexposurestoMNMs
withinsufficienthazarddata,includingcontrolduringaccidentalreleaseandmaintenance
and cleaning operations. The need to apply effective control measures also applies to
environmentalemissionsofMNMs,alongthefulllifecycle.Thesafeoptiontoachievethis
wouldbeamoratorium,i.e.toavoidtheuseofMNMs(andnanoͲenabledproducts).This
option is not advocated by the CSOs that participated in the study. Nevertheless, it is
generally acknowledged that when a choice is made to apply MNMs, releases cannot be
prevented (at all foreseeable and unforeseeable moments) and consequently a zeroͲ
exposure or a zeroͲemission is an illusion. Considering the derivation of acceptable
exposure levels for airborne MNMs generates the dilemma that the existing gaps in
toxicological knowledge make a derivation of healthͲbased exposure levels impossible.
RegulatorsandindustrialstakeholdersintheNetherlandshaveagreedthatpostponingthe
derivationoflimitvaluesforoccupationalexposureuntilmorehazarddatacomeavailable
is not an acceptable option, as that would imply acceptance of the situation as it is,
allowingexposuretoemergingconcentrationsattheworkplace.
Inviewthereof,theconceptofnanoreferencevalues(NRVs)(buildingblocknr5intable
1) has been developed (IFA 2009, Dekkers et al 2010, this thesis) and framed for
provisionaluseattheworkplace.Thestartingpointwastoderiveparticlenumber–based
NRVs for four groups of nanomaterials. This was preferred over a massͲbased approach.
Size,form,biopersistence,anddensitywereusedasparameterstodistinguishthegroups.
Forgranularnanomaterials,assumingasphereͲlikeshapeandstandardizedatadiameter
of100nm,numberͲbasedbenchmarkswerederivedequivalenttoamassconcentrationof
0.1mg/m3.(ThisimpliesthattheequivalentmassͲconcentrationforsmallernanoparticlesis
lower, e.g. for particles with a diameter of 50nm this is 12.5ʅg/m3). For nanofibers
(including carbon nanotubes) the asbestos OEL was used as reference. For soluble and
nonͲbiopersistent nanoparticles a NRV was assigned according to the applicable OEL for
thecoarse(ormolecular)formbecauseregardinghazard,theseparticlesaresupposedto
behavelike‘conventional’substances.
TheNRVsaredefinedas8ͲhourtimeͲweightedaveraged(8hrͲTWA)concentrations,
intendedtobeawarninglevel:whentheyareexceededexposurecontrolmeasuresshould
169
__________________________________________________________________________________
be taken to assure an exposure below this level (see table 2). For shortͲterm peak
exposuresofmaximum15minutesitwasproposedtouseamaximumleveloftwicethe
value of the NRV: NRV15minͲTWA=2xNRV8hrͲTWA. This is in line with the discussions of an
internationalworkshoppresentedinchapter7.
Table2 NanoReferenceValues(NRVs)for4classesofmanufacturednanomaterials
Class Description
Density
1
ǡ Ǧ

2
NRV(8ǦhrTWA)
Examples
ͲǤͲͳȀ͵

Ǧ

ǡ ǡ ʹǡ ǡ ǡ ǡ ǡ ǡ ʹͷǡ
ε͸ǡͲͲͲȀͿ ʹͲǡͲͲͲȀͿ
ͳͳͲͲ
ʹǡ
3
ʹ͵ǡʹǡǡʹǡǡ

ǡ͸Ͳǡǡ
ͳ ͳͲͲδ͸ǡͲͲͲȀͿ ͶͲǡͲͲͲȀͿ
Ǧ

4
Ǧ
Ǧ
ͳͳͲͲ

ǤǤǡ
Thestudypresentedinchapter5ofthisthesisindicatesthatmostcompaniesworkingwith
nanomaterialsacceptNRVsasatooltopreventhazardandrisk.CompaniestendtobeproͲ
activetowardusingtheNRVsforriskassessmentandmanagement.Animportantdriverto
use NRVs seems to be a temporary certainty employers experience regarding their legal
obligationtotakepreventiveaction.Acontributiontothepositiveattitudeofcompanies
towards the NRV may also be the reassuring finding that conventional exposure control
measures are generally adequate as well to control airborne MNMs. Many of the
companiesandregulatorswelcomethevoluntarycharacterofNRVs,buttradeunionsand
afewcompaniesadvocategivingtheNRVsamorebindingstatus.Importantpreconditions
for compliance to use NRVs relate to appropriate and easy available measurement
strategiesatlowcostandanappropriateinformationsupplyaboutnanomaterialsusedin
productsandtheirpossiblereleaseduringintendeduse.Regulatorscanbenefitfromthe
positive motivation posture of companies. To enhance the use of NRVs regulators are
recommended to emphasize the trust building function of NRVs. The Dutch Government
accepted the approach and regards the provisional NRVs as reflecting the best available
scienceandasstateoftheartapproachforriskassessmentofnanomaterials(Atsma2009;
Donner2010).
Asshowninchapters3and4ofthisthesis,theexposuretomanufacturednanomaterials
wasmeasuredatavarietyofworkplaces:intheconstructionindustry(mixinganddrilling
nanoͲenabled concrete), the furniture industry (applying nanopaint and abrasion of
(nano)Ͳpainted surfaces), electroplating, nanopaint manufacturing, manufacturing of
pigment concentrates, production of nonͲreflective glass, manufacturing of fluorescent
tubes,carrepairandrefinishingandasacontrolthemanufacturingofconventionalnonͲ
nano wall paint and the longͲterm testing of wear lubrication. An exposure assessment
strategywasdevelopedtodistinguishexposuretomanufacturednanomaterialsfromthe
ambientbackgroundconcentrationandfromtheconcentrationofnanoparticlesgenerated
at the workplace by processes and equipment used. This assessment strategy allows for
applyingnanoreferencevalueswithoutnecessarilyexaminingthechemicalcompositionof
170
Conclusions
__________________________________________________________________________________
workplace samples. It was found that the use of solid, dispersable manufactured
nanomaterials gives sometimes rise to high airborne NP concentrations near the source
with a rapid dilution further away from the source. Use of manufactured nanomaterials
contained in a fluid, or machining (e.g. abrasion) of surface coated articles with
nanomaterialsͲcontaining paint or coating shows only a very limited or no emission of
airborneNPs.FormostoperationstheexposurecanbecharacterizedbyshortͲtermhigh
peak emissions, but the 8hrͲTWA exposure to manufactured nanomaterials remained in
most cases below the NRV8hrͲTWA. The NRV15minͲTWA is incidentally exceeded at some
workplaces.
Themeasurementspresentedin chapters3and4 ofthisthesisshow that manufactured
nanoparticles are not the only source of workplace exposure to nanoparticles. Also
important can be processͲgenerated nanoparticles (PGNPs). The handling of some
conventional paint components may generate airborne NPs, due to a nanoparticulate
fractioninthesecompounds,andmaygiverisetoalargerNPͲemissionthantheemission
generatedbythemanufacturednanomaterialsused.Combustionprocesses(e.g.theuse
ofdieselengines),theuseofelectromotorsandcontinuouslyrunningmachinesmayalso
generate PGNPs. That the contributions of processͲgenerated nanoparticles to the total
nanoparticles’ exposure cannot be ignored in risk assessment, was acknowledged by the
DutchSocialandEconomicCouncil(SER)thatmadethisfindingpartoftheiradviceonthe
use of nano reference values (SER 2012). It was also taken up by the 7th Joint EU/US
conference on occupational safety and health (EU/US 2012) of trade unions, employers’
organizations and governmental authorities. This conference adopted this issue in their
overarchingprinciplesasfollows:Developharmonizedexposureassessmentmeasurements
andcontrolstrategiesfornanomaterialsandprocessesͲProcessgeneratednanomaterials
cannotbeignoredwhenassessingnanomaterialsattheworkplace.
ThefindingthatitisrelevanttotakeprocessͲgeneratednanoparticlesintoaccount
mayreachfarbeyondtheriskassessmentofworkplaceswithmanufacturednanomaterials
or nanoͲenabled products. For activities with emissions for which a HBͲOEL has been
established, like for example welding operations, it is advisable to reconsider the health
basis of this OEL and to apply the knowledge that is available nowadays on the risks of
exposure to nanoparticles. This thesis advises to apply the NRVs also to the processͲ
generatednanoparticlesbecausethetoxicityisnotnecessarilydifferentfromtheassumed
toxicity of manufactured nanomaterials. The Dutch Social Economic Council decided
differently,anddecidedtodistinguishbetweenmanufacturednanoparticlesandprocessͲ
generatednanoparticles,andtoadvisetheMinisterofSocialAffairstodevelopageneric
healthͲbasedOELforprocessͲgeneratednanoparticles(SER2012).
TheNRVapproachwasintegratedinalaymenͲorientedguidanceforworkingsafelywith
nanomaterialsandnanoproducts(theGuidance).Inchapter6thisapproachwascompared
withtwoqualitativetoolsthatsupportsafeworkingwithmanufacturednanomaterials:the
ControlBandingNanotool(CBN)andtheStoffenmanagerNano(SMN).TheGuidanceand
CBN estimate the emission potential, the SMN estimates the immission potential. The
toolsprovideamodeltoestimatetheriskwhenworkingwithnanomaterials,mayprovide
defaults for lacking hazard data and recommend a level for engineering control. It was
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__________________________________________________________________________________
foundthatthethreetools,whenappliedatthesameworkplaces,estimatedifferencesin
risk levels, but they do not necessarily lead to differences in recommended engineering
control.TheCBNandtheSMNestimateahighriskespeciallywhenhazarddataarelacking.
TheGuidanceestimatesahighrisklevelwhendispersiveMNMsareused.Itwasobserved
that the sensitivity for hazard data is high in the SMN, and low in the CBN and the
Guidance,whilethesensitivityforexposuredataishighfortheCBNandlowfortheSMN
andtheGuidance. TheneglectofprocessͲgeneratednanoparticlesinthethreetoolsmay
leadtoanunderestimationoftheexposuretoworkplaceͲrelatednanoparticleemissions,
andasaconsequencetoanunderestimationofthepotentialrisks.Itwasconcludedthat
the tools studied may have a function in increasing the awareness of workers and SMEs
about the possible risks of nanomaterials. The tools make explicit what hazard and
exposuredataareurgentlyneededtofillthegapstomakeareliableriskassessment.
The NRVͲconcept was also compared with the approach of the British Standards
Institute (BSI), which is a scalingͲdown methodology that derives benchmark levels for
nanomaterialsbasedontheOELasestablishedforthecoarseparticles.TheNRVͲapproach
wasfurthermorecomparedwiththegenericapproachproposedbyPauluhn,whoassumes
lungͲoverloadtobethecriticaleffectformostnanoparticles,derivesanalgorithmwiththe
particles’ density as key element to calculate a derived noͲeffect level for the specific
nanoparticle.ItwasshownthattheNRVapproachasproposedheregivesrisetostricter
exposurelimitsthanthemassͲbasedproposalsofPauluhnandoftentostricterexposure
limitsthanthemassͲbasedBSIproposal.
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divisive messages. February 2009. Available at http://www.eeb.org/?LinkServID=5403FF15Ͳ
9988Ͳ45A3Ͳ0E327CBA2AFD88BA&showMeta=0
ETUC (2008) Resolution on nanotechnologies and nanomaterials Resolution adopted by the ETUC
ExecutiveCommitteeintheirmeetingheldinBrusselson24Ͳ25June2008
ETUC (2010) 2nd resolution on nanotechnologies and nanomaterials, Adopted at the Executive
Committee
on
1Ͳ2
December
2010.
http://www.etuc.org/IMG/pdf/13Ͳ
GB_final_nanotechnologies_and_nanomaterial.pdf
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EU/US(2012).Overarchingprincipleformulatedatthe:7thJointEU/USConferenceonOccupational
IFA(2009):TechnicalInformationÆnanoparticlesattheworkplace:
http://www.dguv.de/ifa/en/fac/nanopartikel/beurteilungsmassstaebe/index.jsp
REACH (2006), REGULATION (EC) No 1907/2006 OF THE EUROPEAN PARLIAMENT AND OF THE
COUNCIL of 18 December 2006 concerning the Registration, Evaluation, Authorisation and
Restriction of Chemicals (REACH), establishing a European Chemicals Agency, amending
Directive 1999/45/EC and repealing Council Regulation (EEC) No 793/93 and Commission
Regulation(EC)No1488/94aswellasCouncilDirective76/769/EECandCommissionDirectives
91/155/EEC, 93/67/EEC, 93/105/EC and 2000/21/EC. See articles 29 and 30. http://eurͲ
lex.europa.eu/LexUriServ/LexUriServ.do?uri=oj:l:2006:396:0001:0849:en:pdf
SER (2009) Social and Economic Council Netherlands. Nanoparticles in the Workplace: Health and
SafetyPrecautions.Advisoryreport0901,2009.TheHague.
Available at http://www.ser.nl/ /media/Files/Internet/Talen/Engels/2009/2009 01/2009
01.ashx
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Summary
T
histhesisstartswithashortoverviewofsomekeyissuesthatareimportantformatters
raisedinthestudy:thedefinitionofnanomaterials,thehazardsofnanomaterials,the
precautionary principle, background nanoparticles and nanoparticles formed during
processesandtheuseofoccupationalexposurelimits.
This thesis uses the nanomaterials’ definition as recommended by the European
Commission: primary particles with a sizeͲrange of 1Ͳ100nm. When nanomaterials are
measuredinthisthesisthedetectionlimitsofthemeasuringequipment(10Ͳ300nm)areused.
Thus, airborne assemblies with a diameter 100–300nm are also taken into account. The
European Commission underlines that its definition of nanomaterials not only includes
manufacturednanomaterialsbutalsoregardsthebackgroundand‘incidental’nanomaterials.
‘Incidental nanomaterials’ may be generated by the equipment used or released from (nonͲ
nano)bulkmaterialscontainingananoparticulatefraction.
The hazards of nanomaterials are studied, but knowledge of the specific hazards
relatedtothenanoͲcharacteristicsisstilllimited. Experimentalanimal andcelltissuestudies
with manufactured nanomaterials (MNMs) and epidemiological studies on the effects of
(environmental) airborne particulate pollutants make it likely that exposure to MNMs may
leadtoadversehealtheffects.Oxidativestressleadingtoinflammationislikelytobeoneof
thekeymechanismsunderlyinghazard.Oxidativestressisexhibitedbymanynanoparticlesof
different size, chemical composition and form. As a result of prolonged high exposure to
reactivenanoparticlesoxidativestressmaygiverisetoanongoinginflammation,whichislikely
toworsenbronchitisorasthmainthosewhoalreadyhavealungdiseaseandmayevencause
lungfibrosis.Ongoinginflammationorgenotoxiceffectsofreactivenanoparticlescouldleadto
lung cancer if exposures are high enough and for a prolonged period. AsbestosͲlike effects,
includingmesothelioma mightbe expectedfrom exposuretorigidpersistentfreenanofibers
with a high aspect ratio. Also there might be effects of nanoparticles on other organs. It is
emphasizedthatavailableobservationsonthetoxicityofmanufacturednanoparticlesandthe
earlystageofriskassessmentwithalackofdatajustifiesapplyingaprecautionaryapproachin
assessingtherisksofmanufacturednanomaterials.
Manystakeholdersadvisetousetheprecautionaryprinciplefortheuncertaintiesand
ambivalences as they are encountered with nanomaterials. The principle has a deliberative
natureanditisbasedonnormativequalifiers.Theseregardissuessuchaswhentoinvokethe
precautionaryprinciple(toactratherthannottoact),thelevelofprotectionaimedat,acostͲ
benefit analysis balanced with health considerations, the burden of proof of adverse effects
and the timing, the proportionality of precautionary actions, uncertainties and lack of
knowledge, the seriousness of possible adverse effects, and what level to use as provisional
standard. The precautionary principle is also a fundamental principle in the EU legislative
framework and as such it may stimulate industrial users of nanotechnologies to carefully
considerthewayinwhichtheyintendtoapplythenovelnanomaterialsthatlacktheessential
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hazard data needed for a reliable risk assessment in their products and processes. It may
stimulateindustrytodevelopaprecautionaryapproachtooperationalizehowtheyintendto
dealwithuncertain, ambivalenthumanand environmentalrisks.The precautionaryprinciple
allows CSOs to give an interpretation of normative qualifiers used for defining safe and
sustainablenanomaterialsandnanoproductsandtocontributetotheformulationofasocially
acceptableprecautionaryapproach.
The focus of the nanodebate is predominantly on the risks of manufactured
nanomaterials, but nanomaterials are also formed by electrical equipment, heating and
combustionprocessesormaybereleasedfromthenanoparticulatefractioninbulkmaterials.
In this thesis nanomaterials generated by these sources are called processͲgenerated
nanoparticles (PGNPs). The ambient background concentration of nanoparticles is variable
andinurbanenvironmentstronglyimpactedbytrafficandindustrialexhausts.Inurbanareas
with a low level of pollution an average background of 10,000 to 20,000 particles/cm3 is
common.Theparticles’numberconcentrationofprocessͲgeneratednanoparticlesatindustrial
workplaces may be considerable. It is likely that in many cases processͲgenerated
nanoparticleswilldominatetheairbornenanoparticles’numberconcentration.Itisalsolikely
thatairbornePGNPsmaypolluteworkplaceswherenonanomaterialsarehandled.Thus,itis
importanttotakePGNPsintoaccountinriskassessmentofnonͲnanoworkplaceswithheating
orcombustionprocessesorwhenelectricalequipmentisusedorwhendispersivepowdersare
usedwithananoparticulatefraction.Inthesectiononoccupationalexposurelimitsitisnoted
that there are as yet no registered Derived No Effect Levels (DNELs) or legal healthͲbased
occupationalexposurelimits(HBͲOELs)fornanomaterials.Inviewthereofandgivenlargedata
gapsregardingtherisksofnanomaterialstheuseofnanoreferencevalues(NRV)isproposed.
Nanoreferencevaluesarelimitsregardingnanoparticles’numberconcentrationsbasedona
precautionaryapproach.Inthisthesisthefollowingnanoreferencevalueswillbeused.
NanoReferenceValues(NRVs)for4classesofmanufacturednanomaterials
Class
Description
Rigid,biopersistentnanofibers
1 forwhicheffectssimilartothose
ofasbestosarenotexcluded
Density
Ͳ
NRV(8ͲhrTWA)
3
0.01fibers/cm Examples
SWCNT or MWCNT or metal oxide fibers
for which asbestosͲlike effects are not
excluded
Biopersistentgranular
1and100nm
>6,000kg/m³
Ag,Au,CeO2,CoO,Fe,FexOy,La,Pb,Sb2O5,
SnO2,
Biopersistentgranularandfiber
3 formnanomaterialsintherange
of1and100nm
<6,000kg/m³
Al2O3,SiO2,TiN,TiO2,ZnO,nanoclay
CarbonBlack,C60,dendrimers,polystyrene
Nanofibers with excluded asbestosͲlike
effects
ApplicableOEL
e.g.fats,NaCl
NonͲbiopersistentgranular
1and100nm
Ͳ
ForshortͲtermpeakexposuresof15minutesaNRV15minͲTWAof2xNRV8hrͲTWAisused.
Chapter2describesthecapacitybuildingofcivilsocietyorganizations(CSOs),tradeunionsand
nonͲgovernmental environmental organizations, and their positioning as to environmental,
occupationalhealth andethical aspects ofnanotechnologies. Key is theirviewthatthe large
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gapsinknowledgeaboutoccupationalandenvironmentalhazardsandrisksmustbereflected
inriskmanagementanduseofnanomaterialsandnanoͲenabledproducts.TheCSOsadvocate
to apply the precautionary principle when using nanoͲenabled products and call for the
industryandgovernmentstodevelopanoperationalprecautionaryapproach.Sevenbuilding
blocksareformulatedframingaprecautionaryapproach:
1. NodataÆnoexposureandnodataÆnoemission.
2. Reportingofthecontentandtypeofnanomaterialsinproducts(traceability)
3. Registrationofworkerspossiblyexposedtonanomaterials
4. Transparentcommunicationaboutknownandunknownrisks
5. Derivationofworkplaceexposurelimits
6. Developmentofanearlywarningsystem
7. PreͲmarketing approval for all applications of nanotechnologies and nanomaterials as a
centralelementofthepolicyandregulatoryframework
Theissues1,2and5weresubjecttofurtherstudyinthisthesis.
An overview of the use of manufactured nanoparticles in the European construction and
furniture industry is given in chapter 3. The construction industry uses nanomaterials
predominantlyincoatings,cementandconcrete.AEuropeansurveyamongrepresentativesof
workers and employers identifies a high level of ignorance about the availability and use of
nanomaterialsandthesafetyaspectsthereof.BarriersidentifiedforalargeͲscaleacceptance
of nanoͲenabled products are high costs, uncertainties about longͲterm technical material
performance, as well as uncertainties about health risks of the products. Exposure
measurementssuggestexposuresbelowthenanoreferencevalueofconstructionworkersto
nanoparticlesassociatedwiththeuseofnanoͲenabledproducts.Themeasuredparticleswere
within a size range of 20 – 300 nm, with the median diameter below 53nm. Positive
assignmentofthisexposuretothemanufacturednanomaterialsusedortoadditionalsources
ofnanoparticles,liketheelectricalequipmentusedwasnotpossiblewithinthescopeofthis
study.Thefurnitureindustryshowsasimilarpicturebutactivitiesgenerallytakeplaceindoors.
In this sector application of nanomaterials is predominantly found in coatings (scratch
resistant, ǦǦǡ ǡ Ǧǡ Ǧ Ǧ
Ȍ.
The identified information gaps of downstream users regarding availability, benefits
andpotentialrisksareconfirmedbythestudyoninformationsupplyinthepaintvaluechain.
Although this lack of information is generally regarded as a drawback, it is not always
experiencedasproblematicbythedownstreamusersasisshownforpaintcontractors.
Concentration measurements were also carried out during paint manufacturing,
electroplating,lightequipmentmanufacturing,nonͲreflectiveglassproduction,productionof
pigmentconcentratesandcarrefinishing(chapter4).Activitiesmonitoredwerethehandling
ofsolidmanufacturednanoparticles,abrasion,sprayingandheatingofnanoͲenabledproducts
and machining nanosurfaces. The levels of nanoparticles in the workplace air are strongly
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influenced by the physical form of the nanoͲenabled products used, e.g. nanomaterials
embedded in a liquid or solid matrix, and by the control measures taken. Control measures
(e.g. exhaust ventilation) as installed to protect against “conventional” substances, may also
beeffectivetoreduceexposuretonanoparticles.Levelsofnanoparticlesintheworkplaceair,
correctedforthebackground,weremeasuredashighasseveralmillionsofnanoparticles/cm3,
especially during the use of dry, powdery nanomaterials. The 8 hourͲTWA (timeͲweightedͲ
average)numberͲbasedworkplaceconcentrationsgenerallydonotexceedthenanoreference
value. ShortͲterm peak emissions are likely to exceed the 15Ͳminutes TWA nano reference
value (15min peaks) when insufficient control measures are taken. At many workplaces the
airborne nanoparticles may originate from manufactured nanoparticles and from processes
and equipment used (PGNPs). The PGNP are likely to be a significant exposure source and
cannot be ignored in risk assessment. There are strong indications that nonͲnano paint
components like CaCO3, CaSiO3, and talc may contain a substantial fraction of nanosized
particulates giving rise to airborne nanoparticle concentrations as well. It is argued that risk
assessmentsshouldtakeintoaccountthesepotentialsourcesaswell.
The legal obligation foremployers in the EU to take care for a safe workplace is a challenge
withinsufficientinformationsupplyorknowledgegapsonhazardsandrisksofmanufactured
nanomaterials. Chapter 5 investigates the attitude of key stakeholders in industry, trade
unions,branchandemployers’organizationsandgovernmentalpolicyadvisorstowardsnano
reference values (NRVs) that may be used to solve some of these problems. NRVs were
introduced as a voluntary risk management instrument, and differ from healthͲbased
occupational exposure limits (OELs) as being precautionͲbased. A measurement strategy to
allowemployerstopracticallyusetheNRVsandtodealwithsimultaneouslyemittingprocessͲ
generatednanoparticles(PGNP)wasdeveloped.Themotivationalpostureofmostcompanies
appearstobeproͲactiveregardingworkerprotectionandacquiescenttoNRVs.Animportant
driver to use NRVs seems to be a temporary certainty employers experience with regard to
their legal obligation to take preventive action. Many interviewees welcome the voluntary
characterofNRVs,thoughtradeunionsandafewcompaniesadvocateamorebindingstatus.
Chapter6appliesthreequalitativeriskmanagementtoolsformanufacturednanomaterialsto
theworkingenvironmentsasstudiedinchapter4andcomparesthesewiththeNRVͲconcept.
The tools studied are the Guidance working safely with nanomaterials and nanoproducts
(‘Guidance’)andtheControlBandingNanoTool(CBN)bothestimatingtheemissionpotential
of MNMs, and the StoffenmanagerNano (SMN) that estimates the immision potential of
MNMs. Itwas foundthatthe CBN and the SMN estimate a high risk especially when hazard
dataarelacking.TheGuidanceestimatesahighrisklevelwhendispersiveMNMsareused.It
wasobservedthatthesensitivityforchangesmadeinthehazarddataishighintheSMN,and
lowintheCBNandtheGuidance,whilethesensitivityforchangesmadeintheexposuredata
is high for the CBN and low for the SMN and the Guidance. Compared to the measured
nanoparticles’ number based concentrations referred to the quantitative NRV concept, the
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control banding tools are stricter in situations where MNMs with many unknown
characteristicsareatstake.TheCBNandtheSMNignoreprocessͲgeneratednanoparticlesas
potential source and as such may underestimate the potential risks of actual workplace
exposure to nanoparticles. The Guidance draws the attention of the user to this potential
source. All three tools may contribute to raising the awareness of employers and workers
aboutthepotentialrisksofnanomaterials.
Chapter 7 reflects on the opinion of an international forum about the usefulness and
acceptability of the NRV as substitute for HBͲOELs and derived noͲeffect levels (DNELs) for
manufacturednanoparticles.Participantsweresmall&mediumsizeenterprises(SMEs),large
companies, trade unions, governmental authorities, research institutions and NGOs. Topics
discussed were the metrics for measuring nanoparticles, the simultaneous exposure to
manufactured nanomaterials and processͲgenerated nanoparticles, the use of the
precautionary principle, the information gap on applied nanomaterials in nanoͲenabled
products and the appropriateness of soft regulation for precautionary exposure control. The
workshopconcludedthattheNRV,asan8hrsͲtimeweightedaverage,isacomprehensibleand
useful instrument for risk management of professional use of manufactured nanomaterials
with a dispersible character. The question remains whether NRVs, as advised for risk
managementbytheDutchemployers’organizationandtradeunions,shouldbeapartofsoft
regulationorthatamorebindingregulationispreferable.
Chapter 8 draws overall conclusions. There was found to be much unͲawareness amongst
downstreamprofessionalusers,consumersandCSOsaboutthemanufacturednanomaterials
that are marketed in nanoͲenabled products. This unͲawareness regards the type of
nanomaterialsaswellastheirbehavior.Therearelargegapsinknowledgeaboutthepotential
releaseofmanufacturednanoparticlesduringintendeduseoftheproducts,andoverthefull
lifecycle.Theknowledgeaboutthe hazardsofnanomaterialsis rapidly growing,but to date
therearestillmanygapsinknowledgegivingrisetouncertaintiesaboutpotentialhealthrisks.
To date nanotoxicology, i.e. the study of the adverse effects of nanoparticles is still an
emergingscience.Despitetheseknowledgegapsmanufacturednanomaterialsareincreasingly
usedinproducts,andreleaseandexposuredoesoccur.Whereuncertaintiesandambiguities
prevail, the advisability to invoke the precautionary principle is generally acknowledged by
regulators, industry and other stakeholders. However, their visions on how to make the
precautionaryprincipleoperationalforthenanotechnologies’practicemaydiffer.Civilsociety
organizations formulated explicit demands to industry and regulators to transform the
precautionary principle into a precautionary approach that can be applied in practice. The
demandsweresummarizedinsevenbuildingblocksforaprecautionaryapproachandgiverise
tomanyinitiativestakenbyregulatorsandindustry.AsHBͲOELsorDNELsarenotyetavailable
fornanomaterialsprovisionalnanoreferencevalues(NRVs)weredeveloped.
The study shows that the exposure to manufactured nanomaterials in the Dutch
workplaces studied, corrected for the ambient background concentration, is generally below
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theleveloftheNRV8hrͲTWA.Existingcontrolmeasuresfor“conventional”substancesappearto
be also efficient for nanoparticles’ control. The emission of manufactured nanomaterials
depends on the processing conditions, but, for the workplaces studied, can generally be
characterized by shortͲterm peak concentrations. ShortͲterm peak concentrations may
incidentallyexceedtheNRV15minͲTWA.
It is also concluded that nanoparticles’ number concentration at workplaces may be
dominatedbyprocessͲgeneratednanoparticles,whichcannotbeignoredinriskassessment.In
many processes it is possible to distinguish between the background, processͲgenerated
nanoparticlesandthemanufacturednanoparticlesbyapplyingatieredmeasurementstrategy.
InthosecasesitnotnecessarytofullycharacterizesampleswithphysicalͲchemicalanalysis.As
suchariskmanagementstrategyusingtheNRVisaffordableforSMEsusingnanomaterials.
Theconceptofnanoreferencevaluesprovestobeacomprehensibleandacceptable
tool for the companies studied. The companies studied tend to be proͲactive in risk
managementandacquiescenttousetheNRVasameanstofulfilltheemployers’dutyofcare
for a safe workplace. The voluntary character of the NRVͲtool is welcomed by many
companies,butcriticizedbytradeunionsandaminorityofthecompanies.Theypreferamore
bindingstatus.ThestatusoftheNRVas“stateͲofͲtheͲart”,andtherecognitionbyregulating
authorities,maygeneratethetrustinthisinstrumentandfurtherstimulatetheiruse.
182
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183
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184
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Samenvatting
I
ndeinleidingvanditproefschrift“NanoMatters”wordeneenaantalonderwerpenkort
besprokendiecentraalstaaninhetonderzoeknaarderisico’svannanomaterialenen
debeheersingdaarvan.Onderwerpendiehieraandeordekomenzijndedefinitievan
nanomaterialen,detoxiciteitvannanomaterialen,hetvoorzorgsbeginsel,nanodeeltjesdie
aanwezig zijn als achtergrondconcentratie, en nanodeeltjes die worden gevormd tijdens
processen,alsmedeenhetgebruikvangrenswaardenvoorberoepsmatigeblootstelling.
In het proefschrift wordt de definitie voor nanomaterialen gebruikt, zoals die wordt
aanbevolendoordeEuropeseCommissie:primairedeeltjesmeteenafmetingtussen1–
100nm.Voordemetingendiebeschrevenwordeninditproefschrift,wordenoverigensde
detectiegrenzen van de meetapparatuur gehanteerd: 10Ͳ300nm, hetgeen impliceert dat
ook assemblages van deeltjes (agglomeraten en aggregaten) met een diameter van 100Ͳ
300nm worden meegenomen. De Europese Commissie benadrukt dat de door hen
aanbevolen definitie niet enkel betrekking heeft op synthetische nanodeeltjes, maar
tevens nanomaterialen betreft die als achtergrond in het milieu aanwezig zijn, alsmede
“incidentele” nanomaterialen. Deze “incidentele nanomaterialen” kunnen worden
gevormd door de apparatuur waarmee gewerkt wordt en ze kunnen vrijkomen bij het
gebruikvangrove(nietͲnano)materialenwaarineenfractienanodeeltjesaanwezigis.
De toxische eigenschappen van nanomaterialen zijn onderwerp van omvangrijk
onderzoek,maardekennisomtrentdetoxischeeigenschappendiebepaaldwordendoor
despecifiekenanoͲkarakteristiekenisnogbeperkt.Experimenteelproefdieronderzoeken
weefselkweekstudies met synthetische nanomaterialen wijzen er op dat inademing van
nanodeeltjes in verontreinigende lucht tot gezondheidsschade kan leiden. Oxidatieve
stress als gevolg van blootstelling aan nanodeeltjes is een markant voorbeeld van een
toxischmechanismedatkanleidentotontstekingsreacties.Oxidatievestressontstaatals
een reactie op uiteenlopende nanodeeltjes met verschillende afmetingen, chemische
samenstelling en vorm. Een voortdurende hoge blootstelling aan reactieve nanodeeltjes
kan oxidatieve stress veroorzaken met een aanhoudende ontsteking als gevolg, die bij
hiervoor gevoelige personen bronchitis of astma kunnen verergeren. Aanhoudende
ontstekingenofgenotoxischeeffectenvanreactievenanodeeltjeskunnenooktotkanker
leiden als de blootstelling hoog genoeg is en plaatsvindt over een lange periode.
Nanodeeltjes kunnen ook een effect hebben op andere organen. Op basis van de
aanwijzingendieermomenteelzijnaangaandedetoxiciteitvansynthetischenanodeeltjes,
en de nog beperkte kennis aangaande de risico’s, wordt benadrukt dat voor de
beoordeling en beheersing van risico’s (de risicoͲinventarisatie en evaluatie, RI&E) een
voorzorgsbenaderinggerechtvaardigdis.
Veelbelanghebbendenradenaanomhetvoorzorgsprincipetoetepassenvoorde
onzekerheden en ambiguïteiten die zich voordoen bij nanomaterialen. Het
voorzorgsprincipeheefteennormatiefkarakterenkenmerktzichdoorhetoverlegdathet
vereist tussen de betrokken partijen om tot overeenstemming te komen. Dit betreft
onderwerpen zoals de vraag wanneer het voorzorgsprincipe zou moeten worden
toegepast (handelen is beter dan passief niets doen), het nagestreefde
beschermingsniveau, een kostenͲbatenanalyse waarin de gezondheidsaspecten zijn
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meegewogen,debewijslastinzakedenadeligeeffectenendetiming,deproportionaliteit
van de voorzorgsmaatregelen, de onzekerheden en het gebrek aan kennis, de ernst van
mogelijke nadelige effecten en het niveau waarop een voorlopige grenswaarde zou
moeten worden vastgesteld. In de Europese regelgeving is het voorzorgsprincipe een
fundamenteel principe, hetgeen industriële gebruikers van nanotechnologieën ertoe aan
moetzettenzorgvuldigteoverwegenopwelkewijzezijdenieuwenanomaterialenbeogen
toetepasseninhunprocessenenproducten,indiendeessentiëledatadiebenodigdzijn
vooreenbetrouwbarerisicobeoordelingontbreken.Hetvoorzorgsprincipeiseenstimulans
voordeindustrietothetformulerenvaneenvoorzorgsbenadering,waarmeezijdewijze
operationaliseren waarop zij van plan zijn om te gaan met onzekere en ambivalente
humaneͲ en milieurisico’s. Het voorzorgsprincipe stelt maatschappelijke groepen in de
gelegenheidhuneigeninterpretatietegevenvandenormatievekwalificatievanveiligeen
milieusparendenanomaterialenennanoproductenenombijtedragenaandeformulering
vaneenmaatschappelijkaanvaardbarevoorzorgsbenadering.
De nadruk in discussie over nanotechnologie ligt vooral op de risico’s van
synthetische nanomaterialen, maar nanomaterialen worden ook gevormd door de
elektrische apparatuur, door verhittingsͲ en verbrandingsprocessen of kunnen vrijkomen
uitdefractienanodeeltjesingrovedeeltjesvormigematerialen.Inditproefschriftworden
de nanodeeltjes die uit deze bronnen vrijkomen procesͲgegenereerde nanodeeltjes
genoemd(inhetEngels:processͲgeneratednanoparticles–PGNPs).
Deachtergrondconcentratievannanodeeltjesinhetmilieuisvariabelenwordtin
het stedelijk milieu in grote mate bepaald door het verkeer en industriële emissies. In
stedelijke gebieden met een lage luchtverontreiniging treft men gewoonlijk een
achtergrondconcentratie aan van gemiddeld 10.000 tot 20.000 nanodeeltjes/cm3. Op de
werkplek kan de concentratie van PGNPs in de werklucht (in aantallen deeltjes per cm3)
aanzienlijk zijn. Waarschijnlijk zal de concentratie PGNPs in veel gevallen die van
synthetische nanomaterialen overtreffen. Dus ook op werkplekken waar geen
nanomaterialen worden gebruikt kunnen PGNPs de werklucht verontreinigen. Het is
derhalvevanbelangomPGNPsookmeetenemeninderisicobeoordeling(RI&E)vannietͲ
nano werkplekken als er verhittingsͲ of verbrandingsprocessen plaatsvinden, als er
elektrische apparatuur wordt gebruikt of als er dispersieve poeders worden gebruikt
waarineenfractienanodeeltjesaanwezigis(ofkanzijn).
Indeparagraafovergrenswaardenvoorstoffenopdewerkplekwordtvastgesteld
dat er vooralsnog geen wettelijke gezondheidskundige grenswaarden of geregistreerde
“derived noͲeffect levels” (DNEL = afgeleide geenͲeffect niveaus) voor synthetische
nanomaterialen beschikbaar zijn. Daarom, en ook vanwege de vele lacunes in kennis
omtrent de risico’s van nanomaterialen, wordt het gebruik van nanoreferentiewaarden
(NRV) voorgesteld. Nanoreferentiewaarden zijn op voorzorg gebaseerde grenswaarden
betreffendedenanodeeltjesconcentratie(inaantallendeeltjes/cm3)opdewerkplek.Indit
proefschriftwordendevolgendenanoreferentiewaardengebruikt(zietabel1).
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Samenvatting
Tabel 1, Nanoreferentiewaarden (NRVs) voor 4 klassen van synthetische nanomaterialen Klasse Beschrijving Dichtheid NRV (8‐uur tgg) Voorbeelden SWCNT, MWCNT of vezelvormige 1 2 Rigide, biopersistente nanovezels waarvoor asbest‐achtige effecten niet zijn uitgesloten Biopersistente, granulaire nanomaterialen in de range van 1 en 100 nm 3
‐ 0,01 vezels/cm metaaloxiden waarvoor asbest‐achtige niet zijn uitgesloten door de fabrikant. Ag, Au, CeO2, CoO, Fe, FexOy, La, Pb, Sb2O5, > 6.000 kg/m³ 20.000 deeltjes/cm³ SnO2, Al2O3, SiO2, TiN, TiO2, ZnO, nanoklei 3 Biopersistente, granulaire en vezelvormige nanomaterialen in de range van 1 en 100 nm Carbon Black, C60, dendrimeren, polystyreen < 6.000 kg/m³ 40.000 deeltjes/cm³ Nanovezels waarvoor asbest‐achtige effecten expliciet zijn uitgesloten 4 Niet‐biopersistente granulaire nanomaterialen in de range van 1 en 100 nm Gangbare ‐ Vb.: vetten, keukenzout (=NaCl) grenswaarde Voor kortdurende piekblootstellingen van 15 minuten wordt een NRV15min‐tgg gebruikt van 2 x NRV8uur‐tgg. Hoofdstuk 2 beschrijft de capaciteitsopbouw van maatschappelijke organisaties, vakbonden en milieuorganisaties, met betrekking tot hun positionering inzake milieu, arbeidsomstandigheden en ethische aspecten van nanotechnologieën. Het kernpunt in hun opvattingen is dat de grote leemtes in kennis inzake beroepsmatige en milieurisico’s zijn weerslag moet vinden in het risicomanagement en het gebruik van nanomaterialen en producten die hiermee gefunctionaliseerd worden (in het Engels: ‘nano‐enabled products’, en in deze Nederlandse samenvatting kortweg ‘nanoproducten’). De maatschappelijke groepen pleiten er voor om bij het gebruik van nanoproducten het voorzorgsprincipe toe te passen en roepen de industrie en de overheden op een voorzorgsbenadering te operationaliseren. Zij formuleren zeven bouwstenen die het kader vormen voor een voorzorgsbenadering. 1. Geen data Æ geen blootstelling, en geen data Æ geen emissie 2. Rapportage van het gehalte en type nanomaterialen toegepast in het product 3. Registratie van werknemers die mogelijkerwijs blootgesteld worden aan nano‐
materialen 4. Transparante communicatie over bekende en onbekende risico’s 5. Afleiding van grenswaarden voor blootstelling op de werkplek 6. Ontwikkeling van een systeem voor vroegtijdige signalering van nadelige effecten 7. Goedkeuring voorafgaand aan alle toepassingen van nanotechnologieën en nanomaterialen als een centraal element van het beleid en wettelijk kader. Dit promotieonderzoek betreft met name de bouwstenen 1, 2 en 5 . Hoofdstuk 3 geeft een overzicht van het gebruik van synthetische nanomaterialen in de Europese bouwnijverheid en meubelindustrie. De bouwnijverheid past nanomaterialen voornamelijk toe in verven, cement en beton. Onderzoek in Europa onder vertegenwoordigers van werknemers en werkgevers toont een hoge mate van onwetendheid onder deze beroepsgroep betreffende de beschikbaarheid en gebruik van nanomaterialen in de sector en de veiligheid en gezondheidsaspecten hiervan. Een drietal 187 NanoMatters - Building Blocks for a Precautionary Approach
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barrières staat een grootschalige acceptatie van nanoproducten in de weg. Dit zijn in de
eersteplaatsdehogeproductkosten,deonzekerhedenoverdetechnischeprestatiesvan
het nanoproduct op de lange termijn, en ook de onzekerheden aangaande de
gezondheidsrisico’s van de producten. Blootstellingsmetingen uitgevoerd bij de
verwerking (en bewerking) van nanoproducten door werknemers in de bouwnijverheid
wijzen op een hiermee geassocieerde blootstelling die lager is dan de nanoreferentieͲ
waarde.Erwerdendeeltjesindewerkluchtgemetenmeteendiametervariërendtussen
de20en300nmmeteenmediaanbeneden53nm.Hetwasbinnenditonderzoekechter
nietmogelijkomdezeblootstellingexpliciettoeteschrijvenaandegebruiktesynthetische
nanodeeltjes,degebruiktenanoproductenofaandegebruikteelektrischeapparatuur.De
meubelindustrie vertoont een vergelijkbaar beeld, maar verschilt van de bouwnijverheid
vooral in het feit dat de werkzaamheden grotendeels binnenshuis plaatsvinden. In deze
sector blijken nanomaterialen voornamelijk te worden toegepast in coatings (krasvaste,
gemakkelijkͲteͲreinigen, bactericide, waterafstotende, olieafstotende en antiͲgraffiti
coatings).
De geïdentificeerde leemtes in informatie bij de gebruikers van nanoproducten,
betreffende de beschikbaarheid, de baten en de potentiële risico’s van nanomaterialen
wordenbevestigddoorhetonderzoeknaardeinformatievoorzieningoverditonderwerp
in de verfketen. Hoewel het gebrek aan informatie doorgaans als bezwaarlijk wordt
gekenschetst, wordt dit door gebruikers van nanoproducten, zoals in dit onderzoek
schildersbedrijven,nietaltijdalsproblematischervaren,.
Hoofdstuk 4 beschrijft concentratiemetingen in de werklucht die werden uitgevoerd bij
verfbereiding, bij galvaniseren, bij de productie van tlͲbuizen, bij de productie van nietͲ
spiegelendglas,bijhetfabricerenvanpigmentconcentratenenbijautoschadeherstel.De
activiteiten die werden bestudeerd waren het verwerken van vaste poedervormige
synthetische nanomaterialen, schuuractiviteiten, het verspuiten en verhitten van
nanoproducten en het machinaal bewerken van oppervlakken behandeld met een
nanocoating. De concentratie van nanodeeltjes in de lucht op de werkplek blijkt sterk
beïnvloedtewordendoordefysischevormvandegebruiktenanoproducten,bijvoorbeeld
ofhetnanomateriaalisopgenomenineenvloeistofofineenvastematrix.Bepalendzijn
ookdegenomenblootstellingsbeperkendemaatregelen.HetblijktdatbestaandebeheersͲ
maatregelen, die geïnstalleerd zijn om de blootstelling aan ‘conventionele’ stoffen te
beheersen, zoals bijv. een afzuiginstallatie, veelal ook effectief de blootstelling aan
nanodeeltjesreduceren.Hetconcentratieniveaudatopwerkplekkenwerdvastgesteld,en
was gecorrigeerd voor de achtergrondconcentratie aan nanodeeltjes, kon soms wel
oplopen tot enige miljoenen nanodeeltjes/cm3, vooral bij het gebruik van droge,
poedervormige nanomaterialen. De tijdgewogengemiddelde (tgg) deeltjesconcentratie
over een 8Ͳurige werkdag was doorgaans niet hoger dan de nanoreferentiewaarde. Wel
bleek het dat er sprake kon zijn van kortdurende piekblootstellingen waarbij de 15Ͳ
minuten tgg nanoreferentiewaarde soms overschreden werd, met name als er
onvoldoende brongerichte beheersmaatregelen waren genomen. Op veel werkplekken
kunnen de nanodeeltjes zowel afkomstig zijn van synthetische nanodeeltjes als van de
processen en de gebruikte apparatuur (PGNPs). PGNPs leveren waarschijnlijk een
significantebijdrageaandeblootstellingenkunneninderisicobeoordelingnietgenegeerd
188
Samenvatting
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worden. Er zijn ook sterke indicaties dat componenten die worden gebruikt in ‘gewone’
(nietͲnano) verven, zoals bijvoorbeeld CaCO3, CaSiO3 en talk, een substantiële fractie
nanodeeltjesbevatten.Bijgebruikkunnenhieruitooknanodeeltjesindeluchtvrijkomen.
Bijeenrisicobeoordelingmoetookmetdezepotentiëlebronnenterdegerekeningworden
gehouden.
De wettelijke plicht voor werkgevers in de Europese Unie om zorg te dragen voor een
veilige werkplek is een uitdaging, zeker als er onvoldoende informatie voorhanden is en
leemtes in kennis bestaan inzake de toxiciteit en de risico’s van synthetische
nanomaterialen.Inhoofdstuk5wordtonderzochtwatdehoudingisvansleutelfigurenin
de industrie, de vakbonden, brancheͲ en werkgeversorganisaties en beleidsmedewerkers
bijdeoverheid,aangaandedenanoreferentiewaarden(NRVs)diekunnenwordengebruikt
om sommige van deze knelpunten op te lossen. NRVs werden geïntroduceerd als een
vrijwillig risicomanagement instrument. Zij zijn gebaseerd op voorzorg en als zodanig
verschillenzeprincipieelvangezondheidskundigegrenswaarden.Eenmeetstrategiewerd
ontwikkeld die werkgevers in staat moet stellen om de NRVs optimaal in de praktijk te
gebruiken, terwijl zij ook rekening houden met gelijktijdig gevormde PGNP. De meeste
bedrijven tonen zich gemotiveerd en proactief met betrekking tot de bescherming van
werknemersenschikkenzichinhetgebruikvanNRVs.EenbelangrijkedrijfveeromNRVs
tegebruikenlijktdevoorlopigezekerheidtezijndiehetgebruikgeeftmetbetrekkingtot
hun wettelijke verplichting om preventieve maatregelen te nemen. Veel van de
geïnterviewdenstellenhetvrijwilligekaraktervandeNRVsopprijs,hoewelvakbondenen
enkelebedrijvendevoorkeurgevenaaneenbindendeverplichting.
Hoofdstuk 6 maakt een onderlinge vergelijking van de risicobeoordeling die wordt
verkregen met drie kwalitatieve risicomanagement instrumenten, die werden toegepast
op de werkomstandigheden binnen de bedrijven die beschreven werden in hoofdstuk 4.
DeuitkomstenwerdenvervolgensvergelekenmetdetoepassingvanhetNRVͲconcept.De
bestudeerde control banding instrumenten zijn de Handleiding voor veilig werken met
nanomaterialen en –producten (Guidance), de Control Banding Nanotool (CBN) en de
Stoffenmanager Nano (SMN). De Guidance en de CBN maken een schatting van de
potentiële emissie van synthetische nanodeeltjes, de SMN van de potentiële immissie.
VastgesteldwerddatdeCBNendeSMNvooraleenhoogrisicoschatteningevalersprake
isvanontbrekendedata.DeGuidancedaarentegenschatvooraleenhoogrisiconiveauals
er dispersieve synthetische nanomaterialen worden gebruikt. Het blijkt dat de SMN een
hogegevoeligheidheeftvoorveranderingendiewordenaangebrachtintoxiciteitsdata,en
dat deze gevoeligheid laag is bij de CBN en de Guidance, terwijl de gevoeligheid voor
veranderingendiewordenaangebrachtinblootstellingsdatahoogisvoordeCBNenlaagis
voor de SMN en de Guidance. Vergelijkt men de resultaten verkregen met de control
bandinginstrumenten,metmetingenvandedeeltjesaantallenconcentratiesinrelatietot
hetNRVͲconcept,danblijkendecontrolbandinginstrumentenvooraleenhogerrisicointe
schattenbijdebeoordelingvannanomaterialenmetmeerdereonbekendeeigenschappen.
DeCBNendeSMNnegerenPGNPsalspotentiëleblootstellingsbronenkunnenalszodanig
hetpotentiëlerisicovanblootstellingaannanodeeltjesonderschatten.DeGuidanceneemt
de PGNPs evenmin mee in de risicoschatting, maar attendeert de gebruiker wel op deze
189
mogelijke bron en adviseert bij een hoge risicoschatting om additionele metingen uit te voeren. Alle drie de instrumenten leveren een bijdrage aan de kennis van de werkgevers en werknemers over de potentiële risico’s van nanomaterialen. Hoofdstuk 7 reflecteert op de mening van een internationaal forum over de bruikbaarheid en aanvaarbaarheid van de NRV als substituut voor de nog niet vastgestelde gezondheidskundige grenswaarden en DNEL waarden voor synthetische nanomaterialen. Deelnemers in het forum waren vertegenwoordigers van middelgrote en kleine bedrijven (MKB), grote bedrijven, vakbonden, overheden, onderzoeksinstituten en maatschappelijke groepen. Onderwerpen die werden bediscussieerd waren de meeteenheden waarin nanomaterialen zouden moeten worden gemeten, de simultane blootstelling aan synthetische nanodeeltjes en PGNPs, de toepassing van het voorzorgsprincipe, het gebrek aan informatie betreffende welke synthetische nanomaterialen worden toegepast in producten, en of niet‐dwingende regelgeving kan voldoen ingeval blootstellingsbeheersing een voorzorgsbenadering vereist. De workshop concludeerde dat de NRV, als 8‐uur tijdgewogengemiddelde waarde, een begrijpelijk en bruikbaar instrument is voor risicomanagement van het professionele gebruik van dispersieve synthetische nano‐
materialen. De vraag blijft echter bestaan of de NRVs, zoals ze geadviseerd worden door de Nederlandse werkgeversorganisaties en vakbonden voor risicomanagement, een vrijwillig toe te passen instrument zou moeten blijven, of dat het beter is om ze een meer bindend karakter te geven. Hoofdstuk 8 trekt algemene conclusies. Er werd vastgesteld dat het professionele eindgebruikers, consumenten en maatschappelijke organisaties in hoge mate aan kennis ontbreekt over welke synthetische nanomaterialen worden toegepast in producten die op de markt worden gebracht. Deze onbekendheid betreft zowel het soort nanomaterialen als hun gedrag. Er bestaan grote leemtes in kennis over het potentieel vrijkomen van synthetische nanomaterialen gedurende het beoogde gebruik van de producten, maar ook gedurende de gehele levenscyclus. De kennis over de toxiciteit van nanomaterialen groeit wel snel, maar ook op dit punt bestaan er momenteel nog grote hiaten in de kennis, waardoor de onzekerheid over potentiele gezondheidsrisico’s gevoed wordt. Momenteel is nanotoxicologie, de studie van de nadelige effecten van nanodeeltjes, nog een wetenschap in opkomst. Ondanks de vele kennishiaten worden synthetische nanomaterialen in toenemende mate toegepast in producten en vindt er emissie en blootstelling plaats. Tegelijkertijd onderschrijven regelgevers, industrie en andere belanghebbenden allen het belang van het toepassen van het voorzorgsprincipe zolang de onzekerheden en ambiguïteiten bestaan. Hun opvattingen over de wijze waarop het voorzorgsprincipe zou moeten worden geoperationaliseerd voor toepassing in de nanotechnologiepraktijk, lopen echter uiteen. De maatschappelijke groepen formuleerden de expliciete eis om het voorzorgsprincipe te operationaliseren in een praktisch toepasbare voorzorgsbenadering. Zij vatten hun eisen samen in zeven bouwstenen waarmee ze vormgeven aan de door hen beoogde voorzorgsbenadering, hetgeen bij de industrie en regelgevers tot diverse initiatieven heeft geleid. Een van de initiatieven is de ontwikkeling van voorlopige nanoreferentiewaarden als substituut voor de nog niet ontwikkelde gezondheidskundige grenswaarden en DNELs. 190 Samenvatting
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Hetonderzoektoontaandatdeblootstellingaansynthetischenanomaterialenop
deonderzochteNederlandsewerkplekken,gecorrigeerdvoordeachtergrondconcentratie
engemiddeldovereen8Ͳurigewerkdag,inhetalgemeenbenedendeNRVblijft.Hetblijkt
datbestaandebeheersmaatregelen,dieinbedrijvenzijngenomenomdeblootstellingaan
‘conventionele’stoffentebeheersen,doorgaansookefficiëntzijnomdeblootstellingaan
nanodeeltjestebeheersen.Deemissievansynthetischenanomaterialenhangtsterkafvan
de procesomstandigheden, maar voor de werkplekken die werden bestudeerd, kon de
blootstelling veelal worden gekarakteriseerd aan de hand van kortdurende
piekblootstellingen.DezekortdurendepiekconcentratieskunnenincidenteeldeNRVvoor
een15Ͳminutentijdgewogengemiddeldeperiodeoverschrijden.
Ook wordt er geconcludeerd dat de nanodeeltjesconcentratie (in aantal deeltjes
per volume) op werkplekken kan worden gedomineerd door nanodeeltjes die worden
gevormd in het proces of door de apparatuur (PGNPs). Deze kunnen niet worden
genegeerdinderisicobeoordeling.Bijveelprocessenishetmogelijkomaandehandvan
een stapsgewijze meetstrategie een onderscheid te maken tussen de achtergrondͲ
concentratie,dePGNPsendesynthetischenanodeeltjes.Indienhetonderscheidopdeze
wijze gemaakt kan worden is het veelal niet noodzakelijk om luchtmonsters met behulp
van fysischͲchemische analysemethoden volledig te karakteriseren. In die gevallen is het
goedmogelijkomdeNRValsrisicomanagementstrategietegebruiken.
HetblijktdathetNRVͲconcepteenbruikbareenacceptabelemethodiekisvoorde
bedrijven die bestudeerd werden. Deze bedrijven zijn proactief in het risicomanagement
vannanodeeltjesenzijaccepterenhetgebruikvandeNRValseenmiddelomtevoldoen
aan hun zorgplicht voor een veilige werkplek. Veel bedrijven prefereren de NRV als een
vrijwilliginstrument,maardevakbondeneneenminderheidvandebedrijvendenkendaar
andersover.Zijpreferereneeninstrumentmetmeerbindendkarakter.Destatusvande
NRV als standͲvanͲdeͲwetenschap en de erkenning hiervan door regelgevers, schept
vertrouwenvoorhetinstrumentenkanhetverderegebruikstimuleren.
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a meer dan dertig jaren op het grensvlak van wetenschap en samenleving en risico’s van chemische stoffen voor mens en milieu toch nog een proefschrift. Een moment om kort terug te blikken op wat er aan vooraf ging. Het aantal werkgevers was niet bepaald indrukwekkend, van Wetenschapswinkel naar Chemiewinkel en vandaar naar IVAM. Het voordeel is dat je binnen de beperkte huisvestingsradius van enige honderden meters, van de Sarphatistraat, naar de Nieuwe Achtergracht, naar de Roetersstraat en uiteindelijk op meerdere plekken aan de Plantage Muidergracht, de weg tenminste niet kwijtraakt. De inhoud van het werk was dynamischer en de Chemiewinkel, waar mijn feitelijke carrière begon, wist zich op het gebied van de bedenkelijke rol die chemische stoffen voor mens en milieu kunnen spelen, een prominente plaats te veroveren. Het milieuprobleem werd eind van de jaren zeventig pas echt goed ontdekt, tot ver onder het maaiveld. Bodemverontreiniging werd een nationaal probleem, de Volgermeerpolder, de Diemerzeedijk en vele andere verontreinigde locaties brachten hele dorpen op de been. Het Burgercomité Broek in Waterland bracht de dioxineproblematiek direct de universiteit binnen en benadrukte daarmee het belang van maatschappelijk gericht onderwijs en onderzoek en legitimeerde universitaire medewerkers en studenten om in hun werk en in hun studie het probleem te helpen oplossen. Met schep, emmer en lege jampotjes gingen we op pad. Illustere groepen die ten strijde trokken tegen de industrie klopten aan voor advies: Aktiegroep Tegengif op de Nieuwendammerdijk, op pad tegen de uitstoot van Ketjen, het latere AKZO, Aktiegroep Cindroom ten strijde tegen teer en PAKs van de Cindu in Uithoorn. Vele anderen volgden. Met Stichting Reinwater, al jaren gezamenlijk in strijd met tuinders in het Westland tegen de zoutlozingen van de Franse kalimijnen in de Rijn, werden lozingen van fabrieken langs de Rijn geïdentificeerd en bestreden. Honderden liters afvalwater werden uit de lozingspijpen onder water opgezogen, en de dioxines werden aan boord van het aktieschip geconcentreerd. Dichter bij huis werd het stankverspreidende bedrijf Rutte Recycling bij Halfweg bestreden met snuffelploegen, olfactometers en onderzoek naar biofiltratie. Dat was het begin en vele jaren volgden waarin het milieuprobleem steeds professioneler werd aangepakt, en waarin deskundigheid een steeds grotere rol ging spelen. Ook op de werkplek werden de chemische stoffen ontdekt en ook hier waren acties aan de orde van de dag, veelal met vakbonden in de voorste linie, toen nog het NVV en het NKV met hun vele afzonderlijke bonden die later gezamenlijk de FNV vormden. Nog onwetend van wat zich allemaal in het harde bedrijfsleven afspeelde trok ook ik met een horde chemiewinkeliers ten strijde voor de onderliggende in de samenleving. Ook hier illustere groepen zoals de bedrijfsledengroep Hoogovens die in praktisch iedere deelfabriek, van de Oxystaal, de Kooksovens tot de Centrale Werkplaats chemische misstanden aankaartten, en de strijd aanging met de bedrijfsleiding en de bedrijfsartsen. Eens per maand waren er bijeenkomsten van de Districts Advies Commissie Veiligheid, Gezondheid en Welzijn; een groep van 15 – 20 gemotiveerde werknemers uit bedrijven rondom Amsterdam, ik als 195 NanoMatters - Building Blocks for a Precautionary Approach
adviseur chemische stoffen. En dan bespraken we waarmee gewerkt werd en wat er misging. Over wat chemische stoffen allemaal voor verschrikkelijke dingen konden aanrichten bij werknemers was destijds nog maar weinig bekend, zowel bij de werkgever als bij de werknemer. In die begin tachtiger jaren doemden de organische oplosmiddelen op als bedreiging voor menige beroepsgroep, een oplosmiddel voor menige stof, maar een bindmiddel voor de actie. Aanvankelijk werd het vermoeden nog verwoord met voorzichtige vragen zoals: “kan het zijn dat mijn dagelijkse hoofdpijn door de verf veroorzaakt wordt?”, of, “mijn man gedraagt zich de laatste jaren steeds vreemder, kan dit met zijn werk te maken hebben?” Gaandeweg werd duidelijk dat schilders, drukkers, tapijtleggers, reinigers en tal van anderen werden blootgesteld aan onoorbare concentraties die in het ernstigste geval tot vroegtijdige dementie konden leiden. Herkenning van de problematiek, erkenning van de relatie van de klachten met het werk, de lastige diagnose van patiënten in het Solvent Team, de substitutie van oplosmiddelhoudende producten, moesten allemaal stuk voor stuk bevochten worden. De strijd werd heftig gevoerd met de vakbonden, tot op het Binnenhof met oplosmiddelslachtoffers, soms tot in de rechtszaal, en resulteerde tot slot, aan het einde van de negentiger jaren, in vervangingsverplichtigen voor oplosmiddelhoudende producten voor professioneel gebruik. Dit was een van de laatste mijlpalen waarin het Nederlandse arbobeleid, nog onafhankelijk van Europa, voor een eigen weg koos. Ook die tijden zijn veranderd. In Europa was ik al enige jaren bezig met het European Work Hazards Network, een groep van arbo‐activisten, die aanvankelijk in nauwe samenwerking met de regenboogfractie in het Europees Parlement, sinds eind van de jaren tachtig een kritische noot liet horen aangaande belastende arbeidsomstandigheden. Het globale karakter van veel beroepsgebonden aandoeningen werd duidelijk, we konden veel leren van hetgeen er in de landen om heen plaatsvond. Het betekende tevens het begin van Europese samenwerking in vele roemruchte Europese substitutieprojecten, zoals Subsprint aangaande reinigingsmiddelen in de grafische industrie, Sumovera met de betonontkistingsmiddelen in de bouw, LLINCWA aangaande het smeermiddelengebruik in activiteiten in en rondom de binnen‐ en kustwateren. Het betekende ook samenwerking met grote bedrijven. Belastende producten werd de wacht aangezegd en van alternatieven werd aangetoond dat zij prima als substituut konden dienen. Ook de Europese Commissie werd directe opdrachtgever toen we werkten aan de onderbouwing van de Europese verfrichtlijn, die het oplosmiddelgehalte in decoratieve verven moest terugdringen. De hele Europese verfketen kwam over de vloer, spannende tijden. Van andere orde was de samenwerking met restauratoren. Met hen werd onderzoek gedaan naar de oorzaak van specifieke verbruining van prenten in passe‐
partouts in archieven. Ook was er de zoektocht naar mogelijke kristalvorming in papier bij toepassing van massaontzuringsprocessen bij verzuurde boeken in bibliotheken. Detectiveachtig onderzoeken met verrassende uitkomsten. Met kunstenaars werden vooral risicovolle kunstenaarsmaterialen onder de loep genomen en afgezet tegen de ongebruikelijke arbeidsomstandigheden. Begin van het nieuwe millennium doemden donkere wolken aan de horizon. De faculteit besloot zijn activiteiten te rationaliseren, terug naar wat ook de universitaire managers hun “core‐business” noemden, en alle activiteiten die niet tot het fundamentele 196
Epiloog
onderzoek konden werden gerekend, of tot de centrale onderwijstaken behoorden, konden maar beter verdwijnen. De Chemiewinkel werd gedwongen om te privatiseren, en te fuseren met IVAM UvA BV, de private onderzoeksgroep die jaren daarvoor al was afgesplitst van de toenmalige interfacultaire vakgroep Milieukunde. In 2005 werd daarvoor de laatste steen gelegd. Als afdeling Chemische Risico’s gingen we door en toen in die periode de discussie over de toepassing van nanotechnologie opdoemde en de risico’s van nanodeeltjes veel onzekerheid genereerde, sprongen we daar vol in en organiseerden het project NanoCap dat werkte aan de capaciteitsopbouw van de Europese vakbeweging en milieubeweging op dit nieuwe terrein. Aan de discussie over de risico’s van nanodeeltjes, hun potentiële nadelige milieueffecten en de ethische aspecten van de toepassing van nanotechnologie werd volop deelgenomen. NanoCap werd toonaangevend in Europa. Het stelde de vakbeweging en milieubeweging in staat om voorop te lopen in de discussie en de agenda in belangrijke mate te bepalen. De bouwstenen voor de voorzorgsbenadering, the building blocks for a precautionary approach, uitgekristalliseerd in vele discussies binnen NanoCap, werden onderwerp van mijn proefschrift en werden op een aantal punten verder uitgediept. Dit gold met name de ontwikkeling van nanoreferentiewaarden, die bij het ontbreken van gezondheidskundige grenswaarden als substituut hiervoor konden worden ingezet. De Commissie Grenswaarden van de Sociaal Economische Raad, waar ik reeds enige jaren namens de FNV in deelnam, bleek een uitgelezen platform om dit instrument in maatschappelijke zin verder te operationaliseren. Gezamenlijk hebben we hier een belangrijke mijlpaal in het nanoland neergezet. Dat het tot een promotie is gekomen is op zich een verassende wending geweest. Herstructureringen, reorganisaties en directeurswisselingen binnen IVAM verleidden de UvA Holding, waar IVAM organisatorisch onderdeel van uitmaakt, ertoe om mij het genereuze aanbod te doen om in halve werktijd over vier jaar een promotieonderzoek uit te voeren. Het onderwerp kon ik zelf bepalen, op voorwaarde dat de promotie binnen de UvA plaats zou vinden. Nanotechnologie lag voor de hand vanwege de verwachte grote maatschappelijk impact. In dit verband was vooral interessant de omgang met onzekerheden, de grote leemtes in kennis, de potentiële risico’s van nanomaterialen toegepast in producten waarvan nog geen verantwoorde risicobeoordeling gemaakt kan worden, en in dit verband de operationalisering van het voorzorgsprincipe en de rol van maatschappelijke groepen hierin. Het zijn onderwerpen waar ik in ander verband in feite indirect al jaren meer of minder gericht mee bezig was en ze kwamen samen in de nanotechnologie, op het grensvlak van wetenschap en samenleving. Toch had ik aanvankelijk meer ambities. Ik had aanvankelijk gedacht ook nog het onderzoek te kunnen combineren met onderzoek naar de relatie tussen de toepassing van nanotechnologie en tijdsgebonden biologische processen en kringlopen. Als trigger voor de milieuproblematiek en belastende arbeidsomstandigheden boeit het idee van het manipuleren van de tijd mij al jaren; het reduceren van tijdsgebonden processen in steeds kleinere tijdseenheden, dat dit niet zonder consequenties kan blijven en hoe wij daar als samenleving op worden afgerekend. Maar ik moet toegeven, dat was een brug te ver in het onderhavige onderzoek. Ook mijn idee om als zijweggetje in het onderzoek toepassingen van nano in de kunst en restauratietechniek te onderzoeken is er niet van gekomen. Wellicht wat laat in mijn ontwikkeling leerde ik in het promotieonderzoek dat beperking een voorwaarde is om in de wetenschappelijke wereld een stap vooruit te zetten en dat je je moet voegen in het 197 NanoMatters - Building Blocks for a Precautionary Approach
keurslijf van het wetenschappelijke bedrijf. Het was vooral Lucas Reijnders die zich als promotor, en onvermoeibaar strijder voor een gezond milieu, mij heeft ondersteund in het vinden van de juiste vraagstellingen en in het beperken tot hetgeen er echt gecommuniceerd moet worden. En dan is het verrassend te realiseren dat die beperking transparantie en meerwaarde oplevert. In de beperking toont zich de meester. Er blijft dus nog een hoop over om na afloop mee door te gaan. Veel proefschriften eindigen met een lijst van mensen die bedankt worden. Dat doe ik niet, maar al de mensen met wie ik de afgelopen vijfendertig jaar heb samengewerkt, weten dat hun eigenzinnigheid mij veel heeft geleerd, dat ik niet zonder ze had gekund en dat ik ze in mijn hart heb gesloten. 198