APPENDIX 3-VIII SELECTION OF SCREENING THRESHOLDS AND TOXICITY REFERENCE VALUES

Transcription

APPENDIX 3-VIII
SELECTION OF SCREENING THRESHOLDS AND
TOXICITY REFERENCE VALUES
Cenovus Energy Inc.
Pelican Lake Grand Rapids Project
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Thresholds and Toxicity Reference Values
Appendix 3-VIII
December 2011
TABLE OF CONTENTS
SECTION
PAGE
1
INTRODUCTION ....................................................................................................... 1
2
SELECTION OF SCREENING VALUES ................................................................... 2
3
2.1
2.2
2.3
ACUTE INHALATION HUMAN HEALTH THRESHOLDS............................................... 2
CHRONIC INHALATION HUMAN HEALTH THRESHOLDS .......................................... 4
MULTI-MEDIA HUMAN AND WILDLIFE HEALTH SCREENING .................................17
HUMAN HEALTH TOXICITY ASSESSMENT .......................................................... 18
3.1
3.2
3.3
SUMMARY OF CHEMICALS OF POTENTIAL CONCERN ..........................................18
CHEMICAL CLASSIFICATION ..................................................................................... 19
TOXICITY REFERENCE VALUES ................................................................................ 20
4
WILDLIFE TOXICITY ASSESSMENT ..................................................................... 23
5
REFERENCES ........................................................................................................ 24
6
ABBREVIATIONS ................................................................................................... 26
7
GLOSSARY............................................................................................................. 28
LIST OF TABLES
Table 1
Table 2
Table 3
Table 4
Table 5
Acute Inhalation 1-Hour Health-Based Thresholds ................................................ 5
Chronic Air Screening Levels Used in the Chemical Screening Process............. 11
Carcinogenicity Classification of Chemicals of Potential Concern for the
Long-Term Inhalation Assessment ....................................................................... 19
Reference Concentrations for Chemicals of Potential Concern Evaluated
in the Long-Term Inhalation Assessment – Non-Carcinogens ............................. 21
Inhalation Unit Risks for Chemicals of Potential Concern Evaluated in the
Long-Term Inhalation Assessment – Carcinogens ............................................... 22
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Appendix 3-VIII
December 2011
INTRODUCTION
This appendix forms part of the human health risk assessment and wildlife health
risk assessment being completed as part of the Environmental Impact
Assessment for the Cenovus Energy Inc. (Cenovus) Pelican Lake Grand Rapids
Project (the Project). This appendix provides the following values:
•
Screening thresholds to identify Chemicals of Potential Concern
(COPCs) for further analysis following short-term (acute) and long-term
(chronic) inhalation exposures by human receptors; and
•
Toxicity Reference Values (TRVs) applied in the quantitative
assessments in the human and wildlife health risk assessment.
This appendix also provides the selection process for the screening thresholds
and TRVs, and the rationale for their selection. Screening thresholds were
identified for all chemicals with air modelling results for the Application Case.
This includes chemicals emitted by the Project as well as any other chemicals
emitted by existing and approved sources in the area.
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Appendix 3-VIII
December 2011
2
SELECTION OF SCREENING VALUES
2.1
ACUTE INHALATION HUMAN HEALTH THRESHOLDS
To identify COPCs following acute inhalation exposures, peak 1-hour
concentrations of Volatile Organic Compounds (VOCs), acid gases, metals and
Polycyclic Aromatic Hydrocarbons (PAHs) were compared to screening levels
that are protective of human health. The lowest health-based, defensible and
documented value from the following agencies was used for screening:
•
Alberta Environment (AENV 2011);
•
Agency of Toxic Substances and Disease Registry (ATSDR 2011);
•
Ontario Ministry of the Environment (OMOE 2008a,b);
•
California Environmental Protection Agency Office of Environmental
Health Hazard Assessment (CalEPA OEHHA 2011a);
•
Texas Commission on Environmental Quality (TCEQ 2011); and
•
World Health Organization (WHO 2000, 2005).
For some chemicals that are associated with nuisance odours (i.e., ketones,
phenol, styrene, toluene, xylenes, carbon disulphide), odour thresholds were
lower than health-based thresholds and these odour thresholds were selected for
screening. Using the odour-based threshold for these chemicals ensures that
potential sources of odour can be identified. Odour thresholds were also used
where health-based thresholds were not available.
Alberta’s Ambient Air Quality Objectives (AAAQO; AENV 2011) are equal to or
more stringent than National Ambient Air Quality Criteria and Canada-Wide
Standards. Alberta has developed or adopted objectives from other jurisdictions
where there are no national objectives or Canada-Wide Standards. In some
cases, the original source has updated their value(s); however, Alberta has not
yet reviewed and adopted the updated values. Documentation on the derivation
of AAAQOs was often limited.
The ATSDR derives Minimal Risk Levels (MRLs) for non-carcinogenic health
effects based on reliable and sufficient data that identify the target organ(s) of
effect or the most sensitive health effect(s) for a specific duration for a given
route of exposure to the chemical. The ATSDR generally uses the No Observed
Adverse Effect Level/Uncertainty Factor (NOAEL/UF) approach to derive MRLs.
Physiologically Based Pharmacokinetic (PBPK) modelling and Benchmark Dose
(BMD) modelling have also been used in deriving MRLs. The MRLs are set
below levels that may cause adverse health effects in the most sensitive human
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Appendix 3-VIII
December 2011
sub-populations. The MRLs are derived for acute (1 to 14 days), intermediate
(greater than 14 to 364 days), and chronic (greater than or equal to 365 days)
exposure durations.
The MRLs are generally based on the most sensitive chemical-induced end point
considered to be of relevance to humans. However, as MRLs are often based on
animal studies (because of lack of relevant human studies), there is some degree
of uncertainty associated with MRLs because of lack of precise toxicological
information on the people who might be most sensitive (e.g., infants, elderly and
nutritionally or immunologically compromised) to effects of chemicals. The
ATSDR assumes that humans are more sensitive than animals to the effects of
chemicals and that certain people may be particularly sensitive, and uses a
protective approach to address any uncertainties.
The Ontario air quality standards are used to assess emissions from all
non-mobile sources of air pollution in Ontario. The Ontario air quality standards
are generally derived from ambient air quality criteria, and are set at levels
protective of the natural environment and sensitive populations (e.g., children,
the elderly). The OMOE considers available toxicological information in addition
to other environmental information to determine the potential effects of exposure
to a chemical and proposes effects-based air standards based on the limiting or
critical effect(s) (health or environmental considerations) of that chemical. In
general, the OMOE air standards for carcinogens are set at an incremental risk
of one in one million. Air standards for non-carcinogens are generally derived
from 24-hour average reference concentrations (chosen based on available
peer-reviewed toxicological information and key studies with associated limiting
or critical effect[s]). The air standards for non-carcinogens are generally set at a
target hazard quotient of one.
Texas has developed acute and chronic Effects Screening Levels (ESLs) that are
used in the air permitting process to evaluate air dispersion modelling’s predicted
effects. The ESLs are used to evaluate the potential for effects to occur as a
result of exposure to concentrations of chemicals in the air. The ESLs are based
on data concerning health effects, the potential for odours to be a nuisance,
effects on vegetation, and corrosive effects. The ESLs are not ambient air
quality standards. If predicted airborne levels of a chemical do not exceed the
screening level, adverse health or welfare effects are not expected. If predicted
ambient levels of chemicals in air exceed the screening levels, it does not
necessarily indicate a problem but rather triggers a review in more depth. Texas
has developed a guidance document titled, Guidelines to Develop Effects
Screening Levels, Reference Values and Unit Risk Factors (TCEQ 2006), that
outlines the approach and methods used to derived the acute and chronic ESLs.
Texas does not provide supporting documents for all chemicals for which they
have screening values. In some cases, although the Texas ESL may have been
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Appendix 3-VIII
December 2011
the lowest health-based value available, it was not selected to use in the
screening process unless supporting documentation was available.
The CalEPA OEHHA Reference Exposure Levels (RELs) are concentrations of a
chemical at or below which adverse non-carcinogenic health effects are not
anticipated to occur for a specified exposure duration. The RELs are used in risk
assessments to evaluate the potential for adverse non-carcinogenic public health
effects from facility emissions or similar localized sources in the Air Toxics Hot
Spots Program, and from widespread exposures in the Toxic Air Contaminants
Program. The REL is an exposure at or below which adverse non-carcinogenic
health effects are not expected to occur in a human population, including
sensitive subgroups (e.g., infants and children). Supporting documentation was
provided for most of the RELs.
The WHO has produced air quality guidelines to provide a basis for protecting
public health from adverse effects of air pollution. The guidelines are intended to
provide background information and guidance to governments in making risk
management decisions, particularly in setting standards, but their use is not
restricted to this. They also provide information for all who deal with air pollution.
The guidelines may be used in planning processes and various kinds of
management decisions at a community or regional level. Supporting
documentation was provided for all WHO guidelines. Some of the WHO
guidelines are half-hour guidelines based on odour.
The available acute inhalation 1-hour thresholds and the basis of the selected
thresholds are presented in Table 1.
2.2
CHRONIC INHALATION HUMAN HEALTH THRESHOLDS
To identify COPCs following chronic inhalation exposures, acid gases, metals
and PAHs were compared to screening levels that are protective of human
health. The lowest health-based, defensible and documented value from the
following agencies was used for screening:
•
Alberta Ambient Air Quality Objectives (AAAQO) (AENV 2011);
•
United States Environmental Protection Agency’s Regional Screening
Levels (U.S. EPA 2011a);
•
Texas Commission on Environmental Quality Effects Screening Levels
(TCEQ 2011);
•
California Environmental Protection Agency Office of Environmental
Health Hazard Assessment Reference Exposure Levels (CalEPA
OEHHA 2011a);
•
World Health Organization Air Quality Guidelines (WHO 2000, 2005);
and
•
Canadian Council of Ministers of the Environment (CCME 2008).
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Table 1
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Appendix 3-VIII
December 2011
Acute Inhalation 1-Hour Health-Based Thresholds
ATSDR(a)
[µg/m3]
OMOE(b)
[µg/m3]
CalEPA OEHHA(c)
[µg/m3]
TCEQ(d)
[µg/m3]
WHO(e)
[µg/m3]
AAAQO(f)
[µg/m3]
Aluminum
n/a
n/a
n/a
50
n/a
n/a
Antimony
n/a
n/a
n/a
5
n/a
n/a
Arsenic
n/a
n/a
0.2
0.1
n/a
0.1
Barium
Beryllium
n/a
n/a
n/a
n/a
n/a
n/a
5
0.02
n/a
n/a
n/a
n/a
Cadmium
0.03
n/a
n/a
0.1
n/a
n/a
Chromium (total and III)(g)
n/a
n/a
n/a
3.6
n/a
1
Cobalt
n/a
n/a
n/a
0.2
n/a
n/a
Chemical
Metals
Basis of Threshold
The TCEQ threshold for aluminum (metal and insoluble) is based on a health endpoint, but supporting
documentation is not available.
The TCEQ threshold is based on a health endpoint, but supporting documentation is not available.
The CalEPA OEHHA threshold is based on a Lowest Observed Adverse Effect Level (LOAEL) for
decreased fetal weight in mice following maternal inhalation exposure. An uncertainty factor of 1,000
was applied: 10 for extrapolation from animals to humans, 10 for sensitive individuals and 10 for use of
a LOAEL.
The TCEQ threshold for arsenic is based on decreased fetal body weights of maternally exposed rats
to arsenic trioxide. A point of departure human equivalent concentration (PODHEC) was derived and
uncertainty factors were applied (3 for extrapolation from animals to humans, 10 for database
uncertainty, 10 to account for potential sensitive human subpopulations) to derive a Reference Value
(ReV). The ReV was then adjusted for arsenic. This value is currently under review.
The AAAQO threshold was adopted from Texas.
The ATSDR threshold is based on respiratory effects with an uncertainty factor of 300.
The TCEQ threshold applies to all chromium compounds except hexavalent compounds. The
threshold is based on a health endpoint. The critical effect is increased precursor enzymes that are
early indicators of lung damage.
The AAAQO threshold is adopted from the previous TCEQ value.
Copper
n/a
n/a
100
10
n/a
n/a
Gallium
n/a
n/a
n/a
n/a
n/a
n/a
The CalEPA OEHHA threshold is based on the NOAEL for metal fume fever in human workers
exposed to copper dust. An uncertainty factor of 10 was applied to the NOAEL for sensitive
individuals.
The TCEQ threshold is for copper dusts and mists and is based on a health endpoint, but supporting
No 1-hr thresholds are available.
Indium
n/a
n/a
n/a
1
n/a
n/a
Iron
n/a
n/a
n/a
10
n/a
n/a
The TCEQ threshold is for iron (soluble salts) and is based on a health endpoint, but supporting
Lead
n/a
n/a
n/a
Magnesium
n/a
n/a
n/a
Manganese
n/a
n/a
Mercury
n/a
Molybdenum
0.15 (quarterly
average)
1.5 (three-month)
n/a
1.5
50
n/a
n/a
n/a
2
n/a
2
n/a
0.6
0.25
n/a
n/a
n/a
n/a
n/a
30
n/a
n/a
Nickel
n/a
n/a
6
0.33
n/a
6
Palladium
n/a
n/a
n/a
50
n/a
n/a
Phosphorus
n/a
n/a
n/a
1
n/a
n/a
Volume 3
Texas defers to the United States National Ambient Air Quality Standards for lead (1.5 µg/m3 as the
quarterly average primary standard, and 0.15 µg/m3 as the rolling three-month average primary
standard).
Alberta adopted the quarterly average primary standard from TCEQ.
The TCEQ threshold for magnesium chloride is based on a health endpoint, but supporting
Alberta adopted the quarterly average primary standard from TCEQ.
The CalEPA OEHHA threshold is based on nervous system and developmental effects in offspring
following maternal exposure to mercury vapour during pregnancy.
The TCEQ threshold is based on particulate matter, but supporting documentation is not available.
The CalEPA OEHHA threshold is based on a LOAEL (67 µg/m3) for respiratory and immune system
effects noted in metal plating workers with occupational asthma exposed to nickel as nickel sulphate
(NiSO4) for 30 minutes. The LOAEL was converted to 1-hr exposure and a factor of 10 was applied for
LOAEL uncertainty.
The AAAQO threshold is adopted from California.
The TCEQ threshold for phosphorus trichloride is based on a health endpoint, but supporting
Cenovus Energy Inc.
Table 1
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Appendix 3-VIII
December 2011
Acute Inhalation 1-Hour Health-Based Thresholds (continued)
ATSDR(a)
[µg/m3]
OMOE(b)
[µg/m3]
CalEPA OEHHA(c)
[µg/m3]
TCEQ(d)
[µg/m3]
WHO(e)
[µg/m3]
AAAQO(f)
[µg/m3]
Selenium
n/a
n/a
n/a
2
n/a
n/a
Silicon
n/a
n/a
n/a
50
n/a
n/a
Silver
Tin
n/a
n/a
n/a
n/a
n/a
n/a
0.1
20
n/a
n/a
n/a
n/a
Titanium
n/a
n/a
n/a
50
n/a
n/a
Chemical
Basis of Threshold
Vanadium
n/a
n/a
30
0.5
n/a
n/a
Zinc
n/a
n/a
n/a
20
n/a
n/a
The CalEPA OEHHA threshold is based on eye irritation and coughing and increased mucus
production in humans exposed to vanadium pentoxide. An uncertainty factor of 10 was applied to
account for intraspecies variation.
The TCEQ threshold for vanadium pentoxide is based on a health endpoint, but supporting
documentation is unavailable.
Zirconium
n/a
n/a
n/a
50
n/a
n/a
Acenaphthene
n/a
n/a
n/a
1
n/a
n/a
Acenaphthylene
n/a
10.5
n/a
1
n/a
n/a
Anthracene
n/a
0.6
n/a
0.5
n/a
n/a
Benzo(a)anthracene
n/a
n/a
n/a
0.5
n/a
n/a
Benzo(a)pyrene
n/a
0.0033
n/a
0.03
n/a
n/a
Benzo(b)fluoranthene
n/a
n/a
n/a
0.5
n/a
n/a
Benzo(g,h,i)perylene
n/a
3.6
n/a
0.5
n/a
n/a
Benzo(k)fluoranthene
n/a
n/a
n/a
0.5
n/a
n/a
Biphenyl
n/a
60
n/a
2.3
n/a
n/a
Chrysene
Dibenzo(a.h)anthracene
n/a
n/a
n/a
n/a
n/a
n/a
0.5
0.5
n/a
n/a
n/a
n/a
Fluoranthene
n/a
420
n/a
0.5
n/a
n/a
Fluorene
n/a
n/a
n/a
10
n/a
n/a
Indeno(1,2,3-cd)pyrene
n/a
n/a
n/a
0.5
n/a
n/a
Naphthalene
n/a
n/a
n/a
440
n/a
n/a
The TCEQ threshold is based on odour.
Phenanthrene
n/a
n/a
n/a
0.5
n/a
n/a
Pyrene
n/a
0.6
n/a
0.5
n/a
n/a
The OMOE screening level is a median jurisdictional threshold (1/2 hour averaging time).
1,1,2-Trichloroethane
n/a
n/a
n/a
550
n/a
n/a
1,2-Dichloropropane
230
n/a
n/a
460
n/a
n/a
1,3-Butadiene
n/a
n/a
n/a
510
n/a
n/a
Polycyclic Aromatic Hydrocarbons
Volatile Organic Compounds
Volume 3
The OMOE point of impingement guideline is for a single facility and is based on a health endpoint with
a 1/2 hour averaging time. Supporting documentation is not available.
The TCEQ threshold is based on a health endpoint, but supporting documentation is not available, the
threshold is under review.
The OMOE screening level is a jurisdictional threshold (1/2 hour averaging time).
The OMOE screening level is based on odour.
The TCEQ threshold is based on odour and is under review.
The TCEQ threshold for fluorene is based on a health endpoint, but supporting documentation is not
available.
The TCEQ threshold is based on a health endpoint, but supporting documentation is not available, this
threshold is currently under review.
The ATSDR threshold is based on respiratory effects and an uncertainty factor of 1,000 was applied.
The TCEQ threshold is based on an odour endpoint, as a value based on a health endpoint was not
available.
Cenovus Energy Inc.
Table 1
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Appendix 3-VIII
December 2011
ATSDR(a)
[µg/m3]
OMOE(b)
[µg/m3]
CalEPA OEHHA(c)
[µg/m3]
TCEQ(d)
[µg/m3]
WHO(e)
[µg/m3]
AAAQO(f)
[µg/m3]
1,3-Dichloropropene
n/a
n/a
n/a
45
n/a
n/a
Aldehydes (surrogate: acetaldehyde)
n/a
n/a
470
90
n/a
90
Acetone
n/a
n/a
n/a
5,900
n/a
5,900
Acrolein
6.9
n/a
2.5
3.2
n/a
n/a
Benzene
n/a
n/a
1,300
170
n/a
30
C2-C6 Aliphatic (surrogate: 1-pentyne)
C6-C8 Aliphatic (surrogate: heptanes)
C8-C10 Aliphatic (surrogate: methyl octane)
C8-C10 Aromatic (surrogate: isobutyl benzene)
C10-C12 Aliphatic (surrogate: undecane)
C12-C16 Aliphatic (surrogate: tetradecane)
C10-C12 Aromatic (surrogate: hexyl benzene)
C12-C16 Aromatic (surrogate: octyl benzene)
C16-C21 Aliphatic (surrogate: nonadecane)
C21-C34 Aliphatic
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
1,000
3,500
3,500
1,250
3,500
3,500
1,250
1,250
100
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
Carbon tetrachloride
n/a
n/a
1,900
130
n/a
n/a
Chlorobenzene
n/a
n/a
n/a
460
n/a
n/a
39,580
n/a
n/a
500
n/a
n/a
Chloroform
490
n/a
150
100
n/a
n/a
Cumene
n/a
n/a
n/a
500
n/a
500
12,020
n/a
n/a
720
n/a
n/a
n/a
n/a
n/a
19,000
n/a
n/a
4,000
n/a
n/a
n/a
n/a
n/a
21,710
n/a
n/a
740
n/a
2,000
n/a
n/a
n/a
1,400
n/a
n/a
Chemical
Chloroethane
1,4-Dichlorobenzene
Dichloroethanes
Ethanol
Ethylbenzene
Ethylene
Volume 3
Basis of Threshold
Acetaldehyde was used as a surrogate for aldehydes. The CalEPA OEHHA threshold is based on a
LOAEL from a human study. The critical effects of the study include sensory irritation in bronchi, eyes,
nose and throat.
For the AAAQO, acetaldehyde was used as a surrogate for aldehydes and is adopted from Texas.
The AAAQO is based on the TCEQ value.
The ATSDR threshold is based on the LOAEL for a decrease in respiratory rate and nose and throat
irritation in a study of human volunteers. The LOAEL was corrected for intermittent exposure and an
uncertainty factor was applied.
The CalEPA OEHHA threshold is based on a geometric mean of two reference exposure levels
(2.3 µg/m3 and 2.7 µg/m3) from two studies for subjective ocular irritation in human volunteers.
The CalEPA OEHHA threshold is based on health effects (reproductive and developmental toxicity).
The TCEQ threshold is based on hematotoxic effects (depressed peripheral lymphocytes and
depressed mitogen-induced blastogenesis of femoral B-lymphocytes in male mice). A cumulative
uncertainty factor of 90 was applied (3 for interspecies variation, 10 for intraspecies variation, 3 for
extrapolation from a LOAEL to a NOAEL, and 1 for database uncertainty). The effects screening level
was determined based on a target hazard quotient of 0.3.
The AAAQO threshold is adopted from the previous TCEQ value. The AAAQO of 30 μg/m3 for
benzene is based on the former TCEQ health–based short-term ESL. The value was derived by
applying a factor of ten to the TCEQ long-term (annual) ESL of 3 μg/m3.
Acute thresholds were not available.
The CalEPA OEHHA threshold is based on fetal growth retardation in a rat study with a cumulative
uncertainty factor of 1,000.
This threshold is currently under review.
The ATSDR threshold is based on developmental effects with an uncertainty factor of 100.
The ATSDR threshold is based on hepatic effects with an uncertainty factor of 30.
The CalEPA OEHHA threshold is based on fetotoxicity in rats with an uncertainty factor of 1,000.
This threshold is currently under review.
The AAAQO is adopted from Texas.
The ATSDR threshold is based on ocular effects with an uncertainty factor of 10.
The OMOE threshold is based on odour.
The ATSDR threshold is based on neurological effects with an uncertainty factor of 30.
The TCEQ threshold is based on an odour endpoint; a health endpoint was not available. This
threshold is currently under review.
The AAAQO threshold is adopted from the TCEQ threshold.
Cenovus Energy Inc.
Table 1
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Appendix 3-VIII
December 2011
ATSDR(a)
[µg/m3]
OMOE(b)
[µg/m3]
CalEPA OEHHA(c)
[µg/m3]
TCEQ(d)
[µg/m3]
WHO(e)
[µg/m3]
AAAQO(f)
[µg/m3]
Ethylene dibromide
n/a
n/a
n/a
4
n/a
n/a
Formaldehyde
49.1
n/a
55
15
Hexane
n/a
n/a
n/a
5,300
n/a
21,000
Ketones (surrogate: methyl ethyl ketone)
n/a
n/a
13,000
1,300
n/a
n/a
Methanol
n/a
n/a
28,000
2,620
n/a
2,600
2,080
n/a
14,000
3,600
n/a
n/a
Phenol
n/a
n/a
5,800
150
n/a
100
Propylene oxide
n/a
n/a
3,100
70
n/a
480
21,300
n/a
21,000
n/a
70 (30 min)
215
Tetrachloroethanes
n/a
n/a
n/a
70
n/a
n/a
Thiophenes
n/a
n/a
n/a
25
n/a
n/a
Toluene
n/a
n/a
37,000
Trimethylbenzene
n/a
n/a
n/a
1,250
n/a
n/a
Vinyl chloride
n/a
n/a
180,000
20,000
n/a
130
Chemical
Methylene chloride
Styrene
640 (odour)
4,500 (health)
100 (30 min)
1,000 (30 min)
Volume 3
65
1,880
Basis of Threshold
The ATSDR threshold is based on respiratory effects with an uncertainty factor of 9.
The CalEPA OEHHA threshold is based on the benchmark concentration using the dose-response for
eye irritation in humans; an intraspecies uncertainty factor of 10 was applied to account for potential
asthma exacerbation.
The WHO guideline is based on the lowest concentration that has been associated with nose and
throat irritation in humans. This concentration would also be associated with negligible risk of upper
respiratory tract cancer in humans.
The AAAQO threshold is based on respiratory effects in humans.
The AAAQO threshold was derived by ratio from the 24-hour California objective based on nervous
system effects.
The CalEPA OEHHA threshold is based on the LOAEL for eye, nose and throat irritation in humans.
An uncertainty factor of 60 was applied; 6 for use of a LOAEL and 10 for sensitive individuals.
The CalEPA OEHHA threshold is based human studies and nervous system effects with an
uncertainty factor of 10.
This threshold is under review.
The AAAQO is adopted from Texas.
The CalEPA OEHHA threshold is based human studies and nervous system effects with an
uncertainty factor of 60.
The CalEPA OEHHA threshold is based on irritation of the ears, nose and throat in a human study with
an uncertainty factor of 10.
The AAAQO is adopted from Ontario (previous value)
The CalEPA OEHHA threshold is based on dyspnea in mice with an uncertainty factor of 10.
The AAAQO is adopted from Oklahoma.
The CalEPA OEHHA threshold is based on eye and upper respiratory irritation.
The WHO guideline is based on the odour detection threshold for a 30 minute average.
The AAAQO threshold is adopted from Texas (previous value).
The TCEQ thresholds are based on health endpoints, but supporting documentation is not available.
The TCEQ threshold is based on a health endpoint for dibenzothiophene, but supporting
The CalEPA OEHHA threshold is based on a LOAEL (100 ppm) for headaches, dizziness and slight
eye and nose irritation in human males exposed for 6 hrs. The LOAEL was extrapolated to represent 1
hr exposure (98 ppm) and an uncertainty factor of 10 was applied for intraspecies differences.
The TCEQ threshold for toluene is based on an odour endpoint. There is also a health-based threshold
based on eye and nose irritation, headaches, dizziness and intoxication in humans. An uncertainty
factor of 10 was applied for intraspecies variability to account for sensitive subpopulations.
The WHO threshold is based on an odour detection threshold.
The CalEPA OEHHA threshold is based on mild headache and dryness of eyes and nose in healthy
humans.
Cenovus Energy Inc.
Table 1
-9-
Appendix 3-VIII
December 2011
Chemical
Xylenes
ATSDR(a)
[µg/m3]
n/a
OMOE(b)
[µg/m3]
3,000 (10 min)
CalEPA OEHHA(c)
[µg/m3]
22,000
TCEQ(d)
[µg/m3]
WHO(e)
[µg/m3]
350
n/a
AAAQO(f)
[µg/m3]
2,300
Acid Gases
Nitrogen dioxide
n/a
400
470
188
200
300
Sulphur dioxide
n/a
690
660
197
n/a
450
Carbon monoxide
n/a
36,200
23,000
40,000
30,000
15,000
Carbonyl sulphide
n/a
n/a
n/a
135
n/a
n/a
Carbon disulphide
n/a
n/a
6,200
30
20 (30 min)
30
Hydrogen sulphide
97.6 (30 min)
n/a
42
n/a
7 (30 min)
14
13 (10 min)
n/a
0.1
Mercaptans
n/a
n/a
(a)
Agency for Toxic Substances & Disease Registry (ATSDR 2011).
Ontario Ministry of the Environment (OMOE 2008a,b).
(c)
California Environmental Protection Agency Office of Environmental Health Hazard Assessment (CalEPA OEHHA 2011a).
(d)
Texas Commission on Environmental Quality (TCEQ 2011).
(e)
World Health Organization (WHO 2000, 2005).
(f)
Alberta Ambient Air Quality Objectives (AAAQO) (AENV 2011).
(g)
The chromium threshold is based upon divalent and trivalent chromium species.
n/a = Not available.
(b)
Note:
Shaded acute thresholds were used in the human health risk assessment.
Volume 3
n/a
Basis of Threshold
The OMOE is based on odour.
The CalEPA OEHHA threshold is based on a LOAEL (198 ppm) for eye, nose and throat irritation in
humans exposed for 30 minutes. The LOAEL was extrapolated to 1 hour (50 ppm) and an uncertainty
factor of 10 was applied for intraspecies differences.
The AAAQO threshold is adopted from Ontario (previous value) which was based on an odour
threshold.
The OMOE threshold is based on health effects, but supporting documentation is not available.
The CalEPA OEHHA threshold is based on increased airway reactivity in asthmatics.
The TCEQ threshold is based on the NAAQO derived from a maximum acceptable threshold (100 ppb)
at which odour will be perceived.
The WHO threshold is based on an increase in bronchial responsiveness in asthmatics.
The AAAQO is based on respiratory effects.
The OMOE threshold is based on health effects, but supporting documentation is not available.
The CalEPA OEHHA threshold is based on impairment of airway function (bronchoconstriction)
especially in asthmatics.
The TCEQ threshold defaults to the United States National Ambient Air Quality Standard (NAAQS).
The AAAQO is based on the Canadian National Ambient Air Quality Objective (NAAQO) derived from
a maximum acceptable threshold that will minimize the effects of pulmonary function.
The OMOE threshold is based on a health endpoint, but supporting documentation is not available.
The CalEPA OEHHA threshold is based on effects of angina in people with known cardiovascular
diseases that are exercising heavily.
The TCEQ threshold is based on the United States National Ambient Air Quality Standard. No
supporting documentation is available.
The WHO threshold is based on the Coburn-Foster-Kane exponential equation, which takes into
account all the known physiological variables affecting carbon monoxide uptake. The threshold was
determined so the carboxyhaemoglobin level of 2.5% is not exceeded, even when a subject engages
in light or moderate exercise.
The AAAQO threshold is based on the oxygen carrying capacity of blood.
The TCEQ threshold is based on an odour endpoint.
The CalEPA OEHHA threshold is based on reductions in fetal body weight in a rat study.
The WHO threshold is based on an odour threshold.
The AAAQO is based on an odour threshold.
The ATSDR threshold is based on a Lowest Observed Adverse Effect Level (LOAEL) for changes in
airway resistance and airway conductance in asthmatic humans. An uncertainty factor was applied to
the LOAEL.
The CalEPA OEHHA threshold is based on the geometric mean of the range of LOAELs for
physiological responses to odour (headache, nausea) in humans. No uncertainty factor was applied to
the LOAEL.
The WHO threshold is based on an odour threshold.
The AAAQO threshold is based on odour perception.
The OMOE threshold is based on odour.
The TCEQ threshold is based on odour for amyl mercaptan, but supporting documentation is not
available.
Cenovus Energy Inc.
- 10 -
Appendix 3-VIII
December 2011
Health-based values from agencies such as Health Canada and the U.S. EPA
(Integrated Risk Information System) were not used in the chemical screening
process because these values or TRVs are more appropriately used for
comparison to estimated exposures to characterize risks; this is discussed further
in Section 3.3.
To add conservatism to the chemical screening process, the selected screening
level for non-carcinogens was divided by five, which is the default interaction
magnitude as per the U.S. EPA Supplementary Guidance for Conducting Health
Risk Assessment of Chemical Mixtures (U.S. EPA 2000). This adjustment was
done to account for potential cumulative effects that could occur from exposure
to multiple chemicals. No further adjustment was done for carcinogens, given
-6
that screening values were already calculated or adjusted to a 1x10 (one-in-one
-5
million) risk level, which is 10-fold more conservative than the 1x10 risk level
used in the human health risk assessment.
The screening levels available from the agencies listed above are shown in
Table 2.
Risk levels for which the screening levels were derived were
standardized. For non-carcinogens this involved adjusting to a hazard quotient
-6
of 1.0 and for carcinogens this involved adjusting to a risk level of 1x10
(i.e., one-in-one million). The risk levels for which the screening levels were
developed are noted in the column headers for each regulatory agency. Further
information on the approach used to develop the screening levels for each of the
agencies is provided below.
Alberta Environment has developed 24-hour and annual AAAQO for several
chemicals. The objectives are based on scientific, social, technical and
ecological considerations. Only health-based values are used herein for chronic
screening.
The U.S. EPA has developed Regional Screening Levels (RSLs) for air quality
based on the protection of human health. Screening levels are risk-based
concentrations derived from standardized equations combining exposure
information assumptions with U.S. EPA toxicity data. The RSLs are considered
by the U.S. EPA to be protective for humans (including sensitive groups) over a
lifetime. Chemical concentrations above the RSL would not automatically
designate a health risk; however, exceeding a RSL suggests that further
evaluation of the potential risks is appropriate. The RSLs shown in Table 2 are
the values derived for the protection of residential land use.
Volume 3
Cenovus Energy Inc.
Table 2
- 11 -
Appendix 3-VIII
December 2011
Chronic Air Screening Levels Used in the Chemical Screening Process
Chemical
(a)
(b)
Air Screening Levels
[µg/m3]
CalEPA
WHO(d)
OEHHA(c)
(HQ =1,
(HQ=1,
RL=10-6)
RL=10-6)
US EPA
(HQ=1, RL=10-6)
TCEQ
(HQ=0.3,RL=10-5)
Aluminum (Non-carcinogenic)
5.2
5 (16.7)
n/a
Antimony (Non-carcinogenic)
n/a
0.5 (1.7)
n/a
AAAQO(e)
CCME(f)
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
0.015
n/a
n/a
n/a
0.00057
0.01 (0.001)
0.00030
0.00066
0.01
n/a
0.52
0.5 (1.7)
n/a
n/a
n/a
n/a
n/a
n/a
0.007
n/a
n/a
n/a
0.001
0.002 (0.0002)
0.00042
n/a
n/a
n/a
n/a
n/a
0.02
n/a
n/a
n/a
0.0014
0.01 (0.001)
0.00024
n/a
n/a
n/a
n/a
n/a
0.04 (0.14)
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
0.00027
0.02 (0.002)
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
1 (3.3)
n/a
0.1 (0.3)
1 (3.3)
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
Non-carcinogenic
n/a
n/a
n/a
0.5 (annual)
n/a
n/a
Carcinogenic
Metals
Arsenic
Non-carcinogenic
Carcinogenic
Barium (Non-carcinogenic)
Beryllium
Cadmium
Non-carcinogenic
Carcinogenic
Non-carcinogenic
Carcinogenic
Chromium (total and III) (Non-carcinogenic)
Non-carcinogenic
Cobalt
Carcinogenic
Copper (Non-carcinogenic)
Gallium (Non-carcinogenic)
Indium (Non-carcinogenic)
Iron (Non-carcinogenic)
Lead
n/a
n/a
0.083
n/a
n/a
n/a
Magnesium (Non-carcinogenic)
n/a
5 (16.65)
n/a
n/a
n/a
Manganese (Non-carcinogenic)
0.052
0.2 (0.7)
0.09
0.15 (annual)
n/a
0.2
(annual)
Mercury (Non-carcinogenic)
0.31
0.025 (0.08)
0.03
1 (annual)
n/a
n/a
Molybdenum (Non-carcinogenic)
n/a
3 (10.0)
n/a
n/a
n/a
n/a
n/a
0.05
n/a
n/a
0.05
(annual)
0.0051
0.059 (0.0059)
0.0038
0.0025
n/a
n/a
Palladium (Non-carcinogenic)
Phosphorus (Non-carcinogenic)
n/a
n/a
5 (16.7)
0.1 (0.3)
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
Selenium (Non-carcinogenic)
21
0.2 (0.7)
20
n/a
n/a
n/a
Silicon (Non-carcinogenic)
Silver (Non-carcinogenic)
Tin (Non-carcinogenic)
Titanium (Non-carcinogenic)
n/a
n/a
n/a
n/a
5 (16.7)
0.01 (0.03)
2 (6.7)
5 (16.7)
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
Vanadium (Non-carcinogenic)
n/a
0.05 (0.2)
n/a
1 (24 hr)
n/a
n/a
Zinc (Non-carcinogenic)
Zirconium (Non-carcinogenic)
n/a
n/a
2 (6.7)
5 (16.7)
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
Nickel
Non-carcinogenic
Carcinogenic
Volume 3
n/a
n/a
Decision Criteria
The U.S. EPA Regional Screening Level (RSL) was the lowest and
supporting documentation was available.
The TCEQ value was selected in the absence of other values.
The Cal EPA OEHHA REL was the only available value and supporting
documentation was available.
The Cal EPA OEHHA adjusted unit risk was the lowest threshold and
The U.S. EPA RSL was the lowest threshold and supporting
The Cal EPA OEHHA adjusted unit risk was the lowest threshold with
supporting documentation.
n/a
n/a
The WHO guideline was the only available value and supporting
The Cal EPA OEHHA adjusted unit risk was the only available value and
n/a
The Cal EPA OEHHA REL was the lowest threshold and supporting
The AAAQO was the lowest threshold (equal to Cal EPA) and supporting
The WHO guideline was the lowest threshold and supporting
The Cal EPA OEHHA REL was the lowest threshold with supporting
documentation.
The WHO guideline was the lowest threshold with supporting
documentation.
Adjusted Value for NonCarcinogens(g)
[µg/m3]
1.04
0.33
0.003
0.10
0.0014
0.004
0.03
0.67
0.067
0.67
0.1
0.01
0.006
2.0
0.01
3.3
0.07
4.0
3.3
0.007
1.3
3.3
0.2
1.3
3.3
Cenovus Energy Inc.
Table 2
- 12 -
Appendix 3-VIII
December 2011
Chronic Air Screening Levels Used in the Chemical Screening Process (continued)
Chemical
(a)
(b)
[µg/m3]
CalEPA
WHO(d)
OEHHA(c)
(HQ =1,
(HQ=1,
RL=10-6)
RL=10-6)
US EPA
(HQ=1, RL=10-6)
TCEQ
(HQ=0.3,RL=10-5)
n/a
n/a
n/a
0.1 (0.3)
0.1 (0.3)
0.05 (0.2)
n/a
n/a
n/a
Benzo(a)anthracene (Carcinogenic)
0.0087
0.05 (0.005)
Benzo(a)pyrene (Carcinogenic)
0.00087
Benzo(b)fluoranthene (Carcinogenic)
Benzo(g,h,i)perylene (Carcinogenic)
Benzo(k)fluoranthene (Carcinogenic)
AAAQO(e)
CCME(f)
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
0.009
n/a
n/a
n/a
0.003 (0.0003)
0.001
0.000012
0.0003
n/a
0.0087
0.05 (0.005)
0.009
n/a
n/a
n/a
n/a
0.05 (0.005)
n/a
n/a
n/a
n/a
0.0087
0.05 (0.005)
0.009
n/a
n/a
n/a
Biphenyl (Non-carcinogenic)
0.42
1 (3.3)
n/a
n/a
n/a
n/a
Chrysene (Carcinogenic)
0.087
0.05 (0.005)
0.091
n/a
n/a
n/a
Dibenzo(a,h)anthracene (Carcinogenic)
0.0008
0.05 (0.005)
0.001
n/a
n/a
n/a
n/a
n/a
0.05 (0.005)
1 (0.1)
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
0.0087
0.05 (0.005)
0.009
n/a
n/a
n/a
n/a
50(167)
9
n/a
n/a
n/a
0.072
n/a
0.03
n/a
n/a
n/a
n/a
n/a
0.05 (0.2)
0.05 (0.2)
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
Non-carcinogenic
n/a
n/a
n/a
n/a
n/a
n/a
Carcinogenic
0.15
55 (5.5)
0.063
n/a
n/a
n/a
Non-carcinogenic
n/a
46 (153)
n/a
n/a
n/a
n/a
Carcinogenic
0.24
n/a
0.1
n/a
n/a
n/a
Non-carcinogenic
n/a
n/a
20
n/a
n/a
n/a
0.081
9.9 (0.99)
0.006
n/a
n/a
n/a
Non-carcinogenic
n/a
4.5 (15)
n/a
n/a
n/a
n/a
Carcinogenic
0.61
n/a
0.063
n/a
n/a
n/a
Non-carcinogenic
n/a
n/a
140
n/a
n/a
n/a
Carcinogenic
1.1
45 (4.5)
0.37
n/a
n/a
n/a
Acetone (Non-carcinogenic)
32,000
590 (1,966)
n/a
n/a
n/a
n/a
Acrolein (Non-carcinogenic)
0.021
0.15 (0.50)
0.35
n/a
n/a
n/a
Acenaphthene (Non-carcinogenic)
Acenaphthylene (Non-carcinogenic)
Anthracene (Non-carcinogenic)
Fluoranthene (Carcinogenic)
Fluorene (Carcinogenic)
Indeno(1,2,3-cd)pyrene (Carcinogenic)
Naphthalene
Phenanthrene (Non-carcinogenic)
Pyrene (Non-carcinogenic)
1,1,2-Trichloroethane
1,2-Dichloropropane
1,3-Butadiene
1,3-Dichloropropene
Aldehydes (surrogate:
acetaldehyde)
Non-carcinogenic
Carcinogenic
Carcinogenic
Volume 3
Decision Criteria
The U.S. EPA RSL was the lowest threshold with supporting
documentation.
documentation.
documentation.
documentation.
documentation.
documentation.
n/a
The U.S. EPA RSL was the only threshold with supporting
documentation.
[µg/m3]
0.07
0.07
0.03
0.08
1.8
0.03
0.03
31
4.0
3.0
28
6400
0.004
Cenovus Energy Inc.
Table 2
- 13 -
Appendix 3-VIII
December 2011
Chemical
(a)
(b)
[µg/m3]
CalEPA
WHO(d)
OEHHA(c)
(HQ =1,
(HQ=1,
RL=10-6)
RL=10-6)
US EPA
(HQ=1, RL=10-6)
TCEQ
(HQ=0.3,RL=10-5)
Non-carcinogenic
n/a
n/a
60
Carcinogenic
0.31
4.5 (0.45)
Non-carcinogenic
1,000
AAAQO(e)
CCME(f)
n/a
n/a
n/a
0.034
0.17
n/a
n/a
n/a
n/a
n/a
n/a
n/a
9.4
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
18,400
1,000
200
1,000
1,000
200
200
n/a
n/a
n/a
n/a
n/a
n/a
Non-carcinogenic
n/a
n/a
40
n/a
n/a
n/a
Carcinogenic
0.41
13 (1.3)
0.024
n/a
n/a
n/a
Chlorobenzene (Non-carcinogenic)
52
46 (153)
1,000
n/a
n/a
n/a
Chloroethane (Non-carcinogenic)
n/a
50 (167)
n/a
n/a
n/a
n/a
Non-carcinogenic
n/a
n/a
300
n/a
n/a
n/a
Carcinogenic
0.11
10 (1)
0.19
n/a
n/a
n/a
420
250 (833)
n/a
n/a
n/a
n/a
Non-carcinogenic
n/a
n/a
800
n/a
n/a
n/a
Carcinogenic
0.22
32 (3.2)
0.09
n/a
n/a
n/a
1.5
400 (1,333)
0.63
n/a
n/a
n/a
n/a
n/a
n/a
700 (24 hr)
n/a
n/a
0.094
4 (0.4)
0.048
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
Non-carcinogenic
n/a
570 (1,900)
2,000
n/a
n/a
n/a
Carcinogenic
0.97
n/a
0.4
n/a
n/a
n/a
n/a
34 (113)
n/a
n/a
n/a
n/a
Benzene
C2-C6 Aliphatic (surrogates
pentane, methyl tertiary butyl
ether [MTBE])
Carcinogenic
C6-C8 Aliphatic
C8-C10 Aliphatic
C8-C10 Aromatic
C10-C12 Aliphatic
C12-C16 Aliphatic
C10-C12 Aromatic
C12-C16 Aromatic
C16-C21 Aliphatic
C21-C34 Aliphatic
C16-C21 Aromatic
C21-C34 Aromatic
C>34 Aliphatic
C>34 Aromatic
Carbon tetrachloride
Chloroform
Cumene (Non-carcinogenic)
1,4-Dichlorobenzene
1,1-Dichloroethane (Carcinogenic)
1,2-Dichloroethane
Non-carcinogenic
Carcinogenic
Ethanol (Non-carcinogenic)
Ethylbenzene
Ethylene (Non-carcinogenic)
Volume 3
Decision Criteria
Chronic thresholds for potential surrogates were reviewed and the value
from U.S. EPA selected for pentane.
Chronic thresholds for potential surrogates were reviewed and the value
from U.S. EPA selected for methyl-tert-butyl-ether.
CCME completed comprehensive toxicological reviews to derive chronic
Reference Concentrations (RfCs) for petroleum hydrocarbon groups.
n/a
n/a
n/a
n/a
n/a
n/a
The Cal EPA OEHHA REL was the only threshold available and
The WHO guideline was the only threshold available and supporting
n/a
documentation.
[µg/m3]
12
200
3680
200
40
200
200
40
40
8.0
10
33
60
84
160
140
400
23
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Table 2
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Appendix 3-VIII
December 2011
Chemical
(a)
(b)
[µg/m3]
CalEPA
WHO(d)
OEHHA(c)
(HQ =1,
(HQ=1,
RL=10-6)
RL=10-6)
US EPA
(HQ=1, RL=10-6)
TCEQ
(HQ=0.3,RL=10-5)
n/a
0.4 (1.3)
0.8
Non-carcinogenic
n/a
n/a
Carcinogenic
0.19
AAAQO(e)
CCME(f)
n/a
n/a
n/a
9
n/a
n/a
n/a
3.3 (0.33)
0.17
n/a
n/a
n/a
730
200 (667)
7,000
n/a
7,000 (24
hr)
n/a
Ketones (surrogate: methyl ethyl ketone) (Non-carcinogenic)
5,200
2,600 (8,666)
n/a
n/a
n/a
n/a
Methanol (Non-carcinogenic)
4,200
262 (873)
4,000
n/a
n/a
n/a
Non-carcinogenic
n/a
n/a
400
3000
n/a
n/a
Carcinogenic
5.2
350 (35)
1.0
n/a
n/a
n/a
210
19 (63.3)
200
n/a
n/a
n/a
Non-carcinogenic
n/a
n/a
30
n/a
30 (annual)
n/a
Carcinogenic
0.66
7 (0.7)
0.27
n/a
n/a
n/a
Styrene (Non-carcinogenic)
1,000
140 (467)
900
260 (1 week)
n/a
n/a
1,1,1,2-Tetrachloroethane (Carcinogenic)
0.33
105 (10.5)
n/a
n/a
n/a
n/a
1,1,2,2-Tetrachloroethane (Carcinogenic)
0.042
7 (0.7)
0.017
n/a
n/a
n/a
Toluene (Non-carcinogenic)
5,200
1,200 (4,000)
300
260 (1 week)
400 (24 hr)
n/a
1,2,4-Trimethylbenzene (Non-carcinogenic)
7.3
125 (417)
n/a
n/a
n/a
n/a
1,3,5-Trimethylbenzene (Non-carcinogenic)
Non-carcinogenic
Vinyl chloride
Carcinogenic
n/a
n/a
125 (417)
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
0.16
1.2 (0.12)
0.013
1
n/a
n/a
Xylenes (Non-carcinogenic)
100
180 (600)
700
n/a
700 (24 hr)
n/a
Nitrogen dioxide (Non-carcinogenic)
n/a
n/a
n/a
40 (annual)
n/a
n/a
Sulphur dioxide (Non-carcinogenic)
n/a
n/a
n/a
20 (24 hr)
125 (24 hr)
n/a
Carbon monoxide (Non-carcinogenic)
Carbonyl sulphide (Non-carcinogenic)
n/a
n/a
n/a
2.6 (8.7)
n/a
n/a
10,000 (8 hr)
n/a
6,000 (8 hr)
n/a
n/a
n/a
Carbon disulphide (Non-carcinogenic)
730
3 (10.0)
800
100 (24 hr)
n/a
n/a
Hydrogen sulphide (Non-carcinogenic)
2.1
n/a
10
150 (24 hr)
4 (24 hr)
n/a
Ethylene dibromide (Non-carcinogenic)
Formaldehyde
Hexane (Non-carcinogenic)
Methylene chloride
Phenol (Non-carcinogenic)
Propylene oxide
Acid Gases
Volume 3
Decision Criteria
The Cal EPA OEHHA REL was the only available threshold and
documentation.
documentation.
documentation.
The AAAQO was the lowest threshold (equal to Cal EPA) and supporting
n/a
The WHO guideline is the only available health-based guideline (the
AAQO is based on vegetation and not shown).
The WHO guideline is the lowest health-based threshold and supporting
documentation is available.
The AAAQO was adopted from the European Union and is based on
human health.
The AAAQO is the lowest available threshold.
The WHO guideline is the lowest threshold and supporting documentation
is available.
The U.S. EPA RSL is the lowest threshold and supporting documentation
is available.
[µg/m3]
0.16
1.8
146
1040
800
80
40
6.0
52
52
1.5
83
20
8.0
4.0
1,200
1.7
20
0.42
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Table 2
Mercaptans (Non-carcinogenic)
(b)
(c)
(d)
(e)
(f)
(g)
Appendix 3-VIII
December 2011
Chemical
(a)
- 15 -
(a)
(b)
US EPA
(HQ=1, RL=10-6)
TCEQ
(HQ=0.3,RL=10-5)
n/a
1.4 (4.7)
[µg/m3]
CalEPA
WHO(d)
OEHHA(c)
(HQ =1,
(HQ=1,
RL=10-6)
RL=10-6)
n/a
AAAQO(e)
CCME(f)
n/a
n/a
n/a
Decision Criteria
The TCEQ threshold is based on health for amyl mercaptan, butyl
mercaptan and ethyl mercaptan, supporting documentation is not
available.
[µg/m3]
0.93
United States Environmental Protection Agency; Regional Screening Level Table; Residential Air Screening Level (U.S. EPA 2011a).
Texas Commission on Environmental Quality (TCEQ 2011). For non-carcinogens, the screening level derived by TCEQ was based on a HQ=0.3 and for carcinogens was based on a risk level of 1x10-5. The values in brackets represent the screening level adjusted to an HQ=1 for
non-carcinogens and a risk level of 1x10-6 for carcinogens.
California Environmental Protection Agency Office of Environmental Health Hazard Assessment (CalEPA OEHHA 2011a). For non-carcinogens, chronic Reference Exposure Levels (RELs) are shown. For carcinogens, inhalation unit risks (based on a risk level of 1 x 10-6) were adjusted to a
risk based concentration and used as a screening value using the following formula: threshold (µg/m3) = 1E-06/unit risk (µg/m3)-1.
World Health Organization (WHO 2000, 2005). Averaging times are shown in brackets. For carcinogens, inhalation unit risks (based on a risk level of 1 x 10-6) were adjusted to a risk based concentration and used as a screening value using the following formula: threshold (µg/m3) =
1E-06/unit risk (µg/m3)-1.
Alberta Ambient Air Quality Objectives (AENV 2011). Alberta does not specify what their hazard quotients and risk level concentrations are set to (e.g., HQ= 1, RL=10-6), therefore no correction factors were applied.
Canadian Council of Ministers of the Environment; Reference Concentrations (RfC) (CCME 2008).
The selected screening level was divided by 5 for non-carcinogenic compounds.
- = Evaluated as a carcinogen.
Notes:
RL= Risk level used by regulatory agency for developing screening levels for carcinogens, HQ = Hazard quotient.
Shaded chronic screening levels were used in the human health risk assessment.
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Appendix 3-VIII
December 2011
The TCEQ has developed acute and chronic ESLs that are used in the air
permitting process to evaluate the predicted effects from air dispersion
modelling. The ESLs are used to evaluate the potential for effects to occur as a
result of exposure to concentrations of chemicals in the air. The ESLs are based
on data concerning health effects, the potential for odours to be a nuisance,
effects on vegetation and corrosive effects. They are not ambient air quality
standards. If predicted airborne levels of a chemical do not exceed the screening
level, adverse health or welfare effects are not expected. If predicted ambient
levels of chemicals in air exceed the screening levels, it does not necessarily
indicate a problem but rather triggers a review in more depth. The TCEQ have
developed a guidance document titled, Guidelines to Develop Effects Screening
Levels, Reference Values and Unit Risk Factors (TCEQ 2006), that outlines the
approach and methods used to derive the acute and chronic ESLs. Currently,
several of the AAAQO are based on values from TCEQ.
The chronic ESLs were used in the screening process and are shown in Table 2.
The TCEQ’s chronic ESLs for non-carcinogens are based on a hazard quotient
-5
of 0.3, and for carcinogens the ESLs are based on a risk level of 1x10 .
Therefore, the non-carcinogenic ESLs were multiplied by a factor of 1.0/0.3
(i.e., 3.333) to adjust to a hazard quotient of 1.0, and the ESLs for carcinogens
-6
were divided by 10 to adjust to a risk level of 1 x 10 ; adjusted values are shown
in brackets in Table 2.
The TCEQ have developed ESLs for over 3,000 chemicals, but only have
supporting documents for approximately 30 chemicals. As discussed above, the
screening hierarchy used gave preference to values with supporting
documentation. Therefore, although the TCEQ ESL may have been the lowest
value available, it was not selected unless supporting documentation was
available. The only exception was when the TCEQ ESL was the only value
available.
The CalEPA OEHHA RELs are concentrations of a chemical at or below which
adverse non-carcinogenic health effects are not anticipated to occur for a
specified exposure duration. The RELs are used in risk assessments to evaluate
the potential for adverse non-carcinogenic public health effects from facility
emissions or similar localized sources in the Air Toxics Hot Spots Program, and
from widespread exposures in the Toxic Air Chemicals Program. The REL is an
exposure at or below which adverse non-carcinogenic health effects are not
expected to occur in a human population, including sensitive subgroups
(e.g., infants and children), exposed to that concentration for a specified duration.
Supporting documentation was available for most of the RELs. The chronic
RELs were used in the screening process and are shown in Table 2. The
chronic RELs for non-carcinogens are based on a hazard quotient of 1.0.
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Appendix 3-VIII
December 2011
The CalEPA OEHHA does not develop RELs or air quality guidelines or
objectives for carcinogens.
Rather the CalEPA OEHHA has developed
inhalation unit risks for use in cancer risk assessments (CalEPA OEHHA 2011a).
The unit risks can be adjusted based on an applicable cancer risk level and used
as screening values. The CalEPA OEHHA unit risks are based on a cancer risk
-6
level of 1 x 10 ; this level was divided by the unit risk to derive a screening value.
The adjusted inhalation unit risks were used in the screening process for
carcinogens and are shown in Table 2.
The WHO has produced air quality guidelines that provide a basis for protecting
public health from adverse effects of air pollution. The guidelines are intended to
provide background information and guidance to governments in making risk
management decisions, particularly in setting standards, but their use is not
restricted to this. The guidelines may be used in planning processes and various
kinds of management decisions at a community or regional level. Supporting
documentation was provided for all WHO guidelines. The WHO provides unit
-6
risks for carcinogens based on a cancer risk level of 1 x 10 ; this level was
divided by the unit risk to derive screening values.
The Canadian Council of Ministers of the Environment (CCME 2008) has
developed Reference Concentrations (RfCs) for petroleum hydrocarbon groups.
These chronic reference concentrations were used as screening criteria for the
petroleum hydrocarbon groups.
The available chronic screening levels and the basis for selection in the chemical
screening process are presented in Table 2.
2.3
MULTI-MEDIA HUMAN AND WILDLIFE HEALTH
SCREENING
A comprehensive chemical screening process was used to identify COPCs for
the multi-media assessments (human and wildlife); this process is described in
Volume 3, Appendix 3-X. There were no COPCs retained for the multi-media
assessments.
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Appendix 3-VIII
December 2011
HUMAN HEALTH TOXICITY ASSESSMENT
This section provides the results of the toxicity assessment for the human health
long-term (chronic) inhalation assessment. Toxicity assessment involves the
classification of the toxic effects of chemicals and the estimation of the amounts
of chemicals that can be received by an organism without adverse health effects.
For each chemical of potential concern, an appropriate TRV was determined
based on a reported mode of action (i.e., threshold vs. non-threshold mode of
action). For threshold chemicals (i.e., generally not a carcinogen), adverse
effects are expected only to occur above a certain dose rate. However, for
non-threshold chemicals (i.e., most carcinogens), theoretically all doses can
exert a toxic effect.
A toxicity assessment is not provided for the human health short-term inhalation
assessment because the TRVs for the identified COPCs (i.e., nitrogen dioxide
and sulphur dioxide) are simply the acute 1-hour screening levels provided in
Table 1. A toxicity assessment is not provided for the human health multi-media
risk assessment because there were no COPCs retained for the multi-media
human health assessment based on the comprehensive chemical screening
process described in Volume 3, Appendix 3-X.
3.1
SUMMARY OF CHEMICALS OF POTENTIAL CONCERN
Based on the screening process outlined in Volume 3, Appendix 3-X, the
following chemicals were retained as COPCs for the long-term inhalation
assessment:
•
nitrogen dioxide;
•
sulphur dioxide;
•
hydrogen sulphide;
•
acrolein;
•
acrolein surrogate;
•
1,3-butadiene surrogate; and
•
formaldehyde.
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Appendix 3-VIII
December 2011
Surrogate chemicals were used to represent chemicals that did not have toxicity
information. The acrolein surrogate represents methacrolein. The 1,3-butadiene
surrogate represents 17 chemicals, including butadienes, heptadienes,
hexadienes, nonadienes, octadienes and pentadienes (Volume 3, Appendix 3-X).
3.2
CHEMICAL CLASSIFICATION
Different agencies and jurisdictions classify chemicals based on their mode of
action (i.e., threshold vs. non-threshold substances). The following section
summarizes the contaminant classification for each of the COPCs retained for
the long-term inhalation assessment.
The chemical classification for each of the COPCs retained based on the U.S.
EPA IRIS database (U.S. EPA IRIS 2011b), Health Canada (2009) and
International Agency for Research on Carcinogens (IARC 2011) is summarized
in Table 3.
Table 3
Carcinogenicity Classification of Chemicals of Potential Concern for
the Long-Term Inhalation Assessment
Chemical
U.S. EPA IRIS
Database (2011b)
Health
Canada
(2009)
IARC (2011)
Assessed as a
Carcinogen
Nitrogen dioxide (NO2)
n/a
n/a
n/a
No
Sulphur dioxide (SO2)
n/a
n/a
Group 3
No
Hydrogen sulphide (H2S)
n/a
n/a
n/a
No
Acrolein (and acrolein surrogate)
n/a
n/a
Group 3
No
1,3-Butadiene (surrogate)
A
(a)
n/a
Group 1
Yes
Formaldehyde
B1
n/a
Group 1
Yes
(a)
The US EPA considers 1,3-butadiene carcinogenic to humans via the inhalation route.
n/a = Not assessed.
Notes: A = known/likely human carcinogen.
B1 = probable human carcinogen - based on limited evidence of carcinogenicity in humans.
Group 1 = carcinogenic to humans.
Group 3 = not classifiable as to carcinogenicity to humans.
For the long-term inhalation assessment, the 1,3-butadiene surrogate and
formaldehyde were assessed as carcinogens.
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3.3
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Appendix 3-VIII
December 2011
TOXICITY REFERENCE VALUES
For the long-term or chronic inhalation assessment, TRVs for non-carcinogenic
chemicals are called RfCs, and TRVs for carcinogenic chemicals are called Unit
Risks (UR). An RfC is an estimate of continuous inhalation exposure to a
chemical by the human population (including sensitive subgroups) that is likely to
be without an appreciable risk of deleterious effects over a lifetime. A UR is the
upper-bound excess lifetime cancer risk estimated to result from continuous
3
exposure to a chemical at a concentration of 1 µg/m in air.
Available RfCs and URs were compiled from the following agencies:
•
Health Canada (Health Canada 2009);
•
United States Environmental Protection Agency’s Integrated Risk
Information System (U.S. EPA 2011b);
•
World Health Organization (WHO 2000);
•
California Environmental Protection Agency (CalEPA 2011b);
•
Agency of Toxic Substances and Disease Registry (ATSDR 2011); and
•
Netherlands National Institute of Public Health and the Environment
(RIVM 2001).
The most conservative of the RfCs or URs (i.e., lowest RfC and greatest UR)
were selected for use in the long-term inhalation assessment. The available
RfCs, selected RfC, and toxicological basis of the RfCs are presented in Table 4.
The available URs, selected URs and the toxicological basis of the URs are
presented in Table 5. The RfCs and URs were compiled only for the COPCs
identified in the problem formulation and summarized in Section 3.1 of this
appendix.
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Table 4
Chemical
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Appendix 3-VIII
December 2011
Reference Concentrations for Chemicals of Potential Concern Evaluated in the Long-Term Inhalation
Assessment – Non-Carcinogens
Reference Concentration
[µg/m3]
Health
Canada(a)
U.S. EPA
IRIS(b)
ATSDR(c)
RIVM(d)
Toxicological Endpoints and Derivations
Other(e)
Acid Gases
IRIS derived an RfC for hydrogen sulphide based on a LOAEL of 41.7 mg/m3 for nasal lesions
of the olfactory mucosa in male rats exposed 6 hours/day, 7 days/week, for 10 weeks. An
uncertainty factor of 300 was applied to the LOAEL; 3 for interspecies differences, 10 for
sensitive populations and 10 for subchronic exposure.
The RfC derived by WHO (2005) is based on outdoor and indoor epidemiology studies which
suggest adverse respiratory effects in children at an annual average nitrogen dioxide
concentrations above the guideline.
Hydrogen
sulphide
n/a
2
n/a
n/a
n/a
Nitrogen dioxide
n/a
n/a
n/a
n/a
40
Sulphur dioxide
n/a
n/a
n/a
n/a
20
The RfC derived by WHO (2005) is based on epidemiology studies showing adverse
respiratory effects at higher concentrations. WHO lowered the guideline from 125 µg/m3 to 20
µg/m3 based on the uncertainty of SO2 in the causality of effects and the need to provide a
more protective guideline than the 2000 value.
Acrolein
n/a
0.02
n/a
n/a
n/a
IRIS derived an RfC for acrolein based on a LOAEL of 0.9 mg/m3 (0.4 ppm) for nasal lesions in
male and female rats exposed to acrolein 6 hours/day, 5 days/week for 13 weeks. An
uncertainty factor of 1,000 was applied (3 for use of a minimal LOAEL, 3 for interspecies
extrapolation using dosimetric adjustments, 10 for extrapolation from subchronic to chronic
duration and 10 to account for human variability and sensitive subpopulations).
Formaldehyde
n/a
n/a
9.8
n/a
n/a
The ATSDR chronic inhalation MRL of 0.008 ppm was derived based on a minimal LOAEL of
0.24 ppm for histological evidence of mild damage to the nasal epithelial tissue in
formaldehyde exposed chemical workers. To derive the MRL, the minimal LOAEL was divided
by an uncertainty factor of 30 (3 for the use of a minimal LOAEL and 10 for human variability).
(a)
Health Canada (Health Canada 2009).
U.S. EPA IRIS (U.S. EPA 2011b).
(c)
Agency for Toxic Substances and Disease Registry (ATSDR 2011).
(d)
RIVM (National Institute of Public Health and the Environment) (RIVM 2001).
(e)
Source of RfC is explained in toxicological endpoint section, as RfCs were available from other jurisdictions.
Note: Bolded RfCs were used in the human health risk assessment. Unless otherwise stated, the most conservative of the available RfCs was chosen (i.e., the lowest).
(b)
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Table 5
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Appendix 3-VIII
December 2011
Inhalation Unit Risks for Chemicals of Potential Concern Evaluated in the Long-Term Inhalation
Assessment – Carcinogens
Chemical
Inhalation Unit Risks
[µg/m3]-1
Health
Canada(a)
U.S.
EPA IRIS(b)
ATSDR(c)
Toxicological Endpoints and Derivations
CalEPA(d)
1,3-Butadiene
n/a
0.00003
n/a
0.00017
The IRIS unit risk is based on an epidemiological study that evaluated the incidence of
leukemia in occupationally exposed workers. EPA used linear extrapolation from an
LEC01 i.e., the 95% lower confidence limit of the exposure concentration associated with
a 1% increase (0.254 ppm), which is derived from a linear relative rate model
age-specific leukemia incidence rate. An adjustment factor of 2 was applied to reflect
evidence from animal studies that extrapolating cancer from a male-only occupational
population may underestimate risk to the general population.
The Cal EPA unit risk was calculated using a linearized multistage procedure based on
the incidence of lung alveolar and bronchiolar neoplasms in female mice following
inhalation exposure.
The IRIS unit risk is based on the incidence of nasal squamous cell carcinomas in male
and female rats following inhalation exposure to formaldehyde.
Formaldehyde
(a)
n/a
0.000013
n/a
0.000006
The Cal EPA unit risk was based on data from a study shown an increase in rat nasal
squamous carcinoma incidence following chronic inhalation exposure to formaldehyde.
The analysis used the linearized multistage procedure which applies pharmacokinetic
interpolation of molecular dosimetry data to the tumor incidence data.
Health Canada (Health Canada 2009).
(b)
IRIS (U.S. EPA 2011b).
(c)
Agency for Toxic Substances and Disease Registry (ATSDR 2011).
(d)
California Environmental Protection Agency (CalEPA 2011b).
Note:
Bolded URs were used in the human health risk assessment. Unless otherwise stated, the most conservative of the available URs was chosen (i.e., the highest).
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Appendix 3-VIII
December 2011
WILDLIFE TOXICITY ASSESSMENT
A toxicity assessment is not provided for the multi-media assessment for wildlife.
This is because there were no COPCs retained for this assessment based on the
comprehensive chemical screening process described in Volume 3,
Appendix 3-X.
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Appendix 3-VIII
December 2011
REFERENCES
AENV (Alberta Environment). 2011. Alberta Ambient Air Quality Objectives. AENV
Air Policy Branch. Edmonton, AB.
ATSDR (Agency of Toxic Substances and Disease Registry). 2006. Toxicological
profile for dichlorobenzenes. U.S. Department of Health and Human
Services, Public Health Service, Agency for Toxic Substances and Disease
Registry. August 2006.
ATSDR. 2011. ATSDR ToxProfiles. http://www.atsdr.cdc.gov/toxprofiles/index.asp
Accessed September 2011.
CalEPA
(California Environmental Protection Agency), OEHHA (Office of
Environmental Health Hazard Assessment). 2011a. OEHHA Acute, 8-hour
and
Chronic
Reference
Exposure
Level
(REL)
Summary.
http://www.oehha.ca.gov/air/allrels.html. Accessed September 2011.
CalEPA, OEHHA. 2011b. Toxicity Criteria Database – Cancer Potency.
http://www.oehha.ca.gov/risk/ChemicalDB/index.asp. Accessed September
2011.
CCME (Canadian Council of Ministers of the Environment). 2008. Canada Wide
Standard for Petroleum Hydrocarbons (PHC) in Soil: Scientific Rationale.
Supporting Technical Document. January 2008.
Health Canada. 2009. Federal Contaminated Site Risk Assessment in Canada Part
II: Health Canada Toxicological Reference Values.
Health Canada.
Ottawa, ON.
IARC (International Agency for Research on Cancer). 2011. IARC Monographs on
the Evaluation of Carcinogenic Risk to Humans.
http://monographs.iarc.fr/ENG/Classification/index.php. Accessed
September 2011.
OMOE (Ontario Ministry of the Environment). 2008a. Ontario’s Ambient Air Quality
Criteria. Standards Development Branch. PIBS#: 6570e. Toronto, ON.
OMOE. 2008b. Jurisdictional Screening Level List A Screening Tool for Ontario
Regulation 419: Air Pollution - Local Air Quality. Standards Development
Branch, OMOE. PIBS #: 6547e Version 1. Toronto, ON.
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Appendix 3-VIII
December 2011
RIVM (National Institute of Public Health and the Environment). 2001. Reevaluation of Human Toxicological Maximum Permissible Risk Levels.
RIVM Report No. 711701 025.
TCEQ (Texas Commission on Environmental Quality). 2006. Guidelines to Develop
Effects Screening Levels, Reference Values and Unit Risk Factors.
Prepared by Toxicology Section, Chief Engineer’s Office. RG-442.
TCEQ. 2011. Effects Screening Levels (ESLs). July 2011.
http://www.tceq.texas.gov/toxicology/esl/list_main.html Accessed
September 2011.
U.S. EPA. (United States Environmental Protection Agency). 2000. Supplementary
Guidance for Conducting Health Risk Assessment of Chemical Mixtures.
Prepared by Risk Assessment Forum Technical Panel. August 2000.
EPA/630/R-00/002.
U.S.
EPA.
2011a. US EPA Regional Screening Level Table.
http://www.epa.gov/region09/superfund/prg/. Accessed September 2011.
U.S. EPA. 2011b. Integrated Risk Information System (IRIS). Cincinnati, OH.
Online Database.
http://cfpub.epa.gov/ncea/iris/index.cfm.
Accessed
September 2011.
WHO (World Health Organization). 2000. Air Quality Guidelines for Europe,
Second Edition. WHO Regional Publications, European Series. No. 91.
Copenhagen, DK.
WHO. 2005. WHO Air Quality Guidelines Global Update 2005 Report on a Working
Group meeting, Bonn, Germany 18-20 October 2005.
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Appendix 3-VIII
December 2011
ABBREVIATIONS
%
µg/m
- 26 -
Percent
3
Micrograms per cubic metre
AAAQO
Alberta Ambient Air Quality Objectives
AENV
Alberta Environment and Water
ATSDR
Agency for Toxic Substances and Disease Registry
BC10
Benchmark concentration at the lower 95% confidence interval expected to
produce a response rate of 1%
BMD
Benchmark Dose
CalEPA
California Environmental Protection Agency
CCME
Canadian Council of Ministers of the Environment
Cenovus
Cenovus Energy Inc.
COPC
Chemical of Potential Concern
e.g.
For example
ESL
Effects Screening Level
H2S
Hydrogen sulphide
HQ
Hazard Quotient
hr
Hour
i.e.
That is
IARC
International Agency for Research on Cancer
IRIS
Integrated Risk Information System
LOAEL
mg/m
3
Lowest Observed Adverse Effect Level
Milligrams per cubic metre
MRL
Minimal Risk Levels
NAAQO
National Ambient Air Quality Objectives
NO2
Nitrogen dioxide (gas)
NOAEL
No Observed Adverse Effect Level
OEHHA
Office of Environmental Health Hazard Assessment
OMOE
Ontario Ministry of the Environment
PAH
PBPK
Physiologically Based Pharmacokinetic
PODHEC
Point of Departure Human Equivalent Concentration
ppb
Parts per billion
ppm
Parts per million
REL
Reference Exposure Level
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Appendix 3-VIII
December 2011
ReV
Reference Value
RfC
Reference Concentration
RfD
Reference Dose
RIVM
Netherlands National Institute of Public Health and the Environment
RL
Risk Level
RSL
Regional Screening Level
SO2
Sulphur dioxide
TCEQ
Texas Commission on Environmental Quality
the Project
TRV
Toxicity Reference Value
U.S. EPA
United States Environmental Protection Agency
UF
Uncertainty Factor
UR
Unit Risks
VOC
Volatile Organic Compound
WHO
World Health Organization
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GLOSSARY
Acute
A stimulus severe enough to rapidly induce an effect within hours after the
exposure.
Alberta Ambient Air
Quality Objective
(AAAQO)
Alberta Ambient Air Quality Objective levels are established for several air
compounds under Section 14 of the Environmental Protection and
Enhancement Act (EPEA). The AAAQOs form an integral part of the
management of air quality in the province, and are used for reporting the
state of the environment, establishing approval conditions, evaluating
proposed facilities with air emissions, assessing compliance near major air
emission sources and guiding monitoring programs.
Alberta Environment
(AENV)
Alberta Environment and Water (AEW): Provincial ministry that
establishes policies, legislation, plans, guidelines and standards for
environmental management and protection; allocates resources through
approvals, dispositions and licenses, and enforces those decisions; ensure
water infrastructure and equipment are maintained and operated effectively;
and prevents, reduces and mitigates floods, droughts, emergency spills and
other pollution-related incidents.
Ambient Air
The air in the surrounding atmosphere.
Benchmark Dose
(BMD)
The exposure level or dose associated with a specific magnitude of response
(i.e., 5 or 15% incidence within the study population).
Carcinogen
An agent that reacts directly with DNA material to cause cancer.
Chemical of
Potential Concern
(COPC)
A chemical that is associated with the Project and is emitted or released into
the environment and poses a potential risk of exposure to humans.
Chronic
The development of adverse effects after extended exposure to a given
chemical. In chronic toxicity tests, the measurement of a chronic effect can
be reduced growth, reduced reproduction or other non-lethal effects, in
addition to lethality. Chronic should be considered a relative term depending
on the life span of the organism.
Concentration
Quantifiable amount of a chemical in environmental media.
Dose
A measure of integral exposure. Examples include: (1) the amount of
chemical ingested; (2) the amount of a chemical taken up; and (3) the product
of ambient exposure concentration and the duration of exposure.
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Dose Rate
Dose per unit time, for example in mg/day, sometimes also called dosage.
Dose rates are often expressed on a per-unit-body-weight basis, yielding
units such as mg/kg body weight/day expressed as averages over some
period, for example a lifetime.
Environmental
Impact Assessment
(EIA)
A review of the effects that a proposed development will have on the local
and regional environment.
Exposure Ratio (ER)
or Hazard Quotient
(HQ)
A comparison between total exposure from all predicted routes of exposure
and the exposure limits for chemicals of concern. This comparison is
calculated by dividing the predicted exposure by the exposure limit. Also
referred to as hazard quotient (HQ).
Hydrogen Sulphide
(H2S)
Hydrogen sulphide is a colourless gas with strong odour of rotten eggs. It
comes from industrial fugitive emissions by way of petroleum refineries, tank
farms for unrefined petroleum products, natural gas plants, petrochemical
plants, oil sands plants, sewage treatment facilities, pulp and paper plants
using the Kraft pulping process and animal feedlots. Natural sources include
sulphur hot springs, sloughs, swamps and lakes.
Lifetime Cancer Risk The chance a person has, over the course of his or her lifetime (from birth to
death) of being diagnosed with or dying from cancer.
Lowest Observed
In toxicity testing, it is the lowest concentration at which adverse effects on
Adverse Effect Level the measurement end point are observed.
(LOAEL)
Multi-Media Risk
Assessment
An assessment that evaluates multiple exposure pathways, including
inhalation, ingestion and dermal contact to multiple environmental media
namely water, soil, air and food. Exposures to the chemicals of concern for
each pathway are summed to determine total exposure for each chemical.
Nitrogen Dioxide
(NO2)
One of the component gases of oxides of nitrogen which also includes nitric
oxide. In burning natural gas, coal, oil and gasoline, atmospheric nitrogen
may combine with molecular oxygen to form nitric oxide, an ingredient in the
brown haze observed near large cities. Nitric oxide is converted to nitrogen
dioxide in the atmosphere. Cars, trucks, trains and planes are the major
source of oxides of nitrogen in Alberta. Other major sources include oil and
gas industries and power plants.
No Observed
In toxicity testing, it is the highest concentration at which no adverse effects
Adverse Effect Level on the measurement end point are observed.
(NOAEL)
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Non-Carcinogen
A chemical that elicits systemic effects and does not cause cancer. The
chemical has a threshold concentration, below which adverse effects are
unlikely.
Polycyclic Aromatic
Hydrocarbon (PAH)
A group of chemicals comprised of two or more benzene rings. PAHs are
ubiquitous in the environment and occur as complex mixtures and not as
single compounds. They are formed during the incomplete combustion of
organic matter (e.g., in auto engines, incinerators and forest fires).
Receptor
The person or organism subjected to exposure to chemicals or physical
agents.
Reference
Concentration (RfC)
An RfC is an estimate of continuous inhalation exposure to a chemical by the
human population (including sensitive subgroups) that is likely to be without
3
an appreciable risk of harmful effects over a lifetime. It is expressed in μg/m .
Reference Dose
(RfD)
Refers to the safe level or dose of a chemical for which exposure occurs
through multiple pathways (i.e., inhalation, ingestion and dermal). It is most
commonly expressed in terms of the total intake of the chemical per unit of
body weight (e.g., µg/kg bw/d). This term applies only to threshold chemicals.
Risk
The likelihood or probability that the harmful effects associated with a
chemical or physical agent will be produced in populations of individuals
under actual conditions of exposure. Risk is usually expressed as the
probability of occurrence of an adverse effect, i.e., the expected ratio between
the number of individuals that would experience an adverse effect at a given
time and the total number of individuals exposed to the factor.
Slope Factor (SF)
An upper-bound estimate of risk per increment of dose calculated using linear
extrapolation for carcinogens.
Sulphur Dioxide
(SO2)
Sulphur dioxide is a colourless gas with a pungent odour. In Alberta, natural
gas processing plants are responsible for close to half of the emissions of this
gas. Oil sands facilities and power plants are also major sources. Others
include gas plant flares, oil refineries, pulp and paper mills and fertilizer
plants.
Toxicity
The inherent potential or capacity of a material to cause adverse effects in a
living organism.
Toxicity Assessment The process of determining the amount (concentration or dose) of a chemical
to which a receptor may be exposed without the development of adverse
effects.
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Toxicity Reference
Value (TRV)
For a non-carcinogenic chemical, the maximum acceptable dose (per unit
body weight and unit of time) of a chemical to which a specified receptor can
be exposed, without the development of adverse effects. For a carcinogenic
chemical, the maximum acceptable dose of a chemical to which a receptor
can be exposed, assuming a specified risk (e.g., 1 in 100,000). May be
expressed as a Reference Dose (RfD) or a Reference Concentration (RfC)
for non-carcinogenic (threshold-response) chemicals or as a Slope Factor
(SF) or Unit Risk (UR) for carcinogenic (non-threshold response) chemicals.
Also referred to as an exposure limit (EL).
Unit Risk (UR)
A UR is the upper-bound excess lifetime cancer risk estimated to result from
3
continuous exposure to a chemical at a concentration of 1 µg/m in air. It is
3
expressed in terms of “per µg/L” in drinking water or “per µg/m ” in air.
Volatile Organic
Compounds (VOC)
Volatile organic compounds refers to organic compounds that readily
evapourate to the atmosphere.
Wildlife
Under the Species at Risk Act, wildlife is defined as a species, subspecies,
variety or geographically or genetically distinct population of animal, plant or
other organism, other than a bacterium or virus that is wild by nature and is
native to Canada or has extended its range into Canada without human
intervention and has been present in Canada for at least 50 years.
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APPENDIX 3-VIII SELECTION OF SCREENING THRESHOLDS AND TOXICITY REFERENCE VALUES

Transcription

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