Canadian Soil Quality Guidelines
for the Protection of Environmental
and Human Health

T

his fact sheet provides Canadian soil quality
guidelines for commonly occurring unsubstituted
polycyclic aromatic hydrocarbons for the
protection of environmental and human health (Table 1;
Figure 1 and 2 provide instructions on how to implement
the PAH guidelines at a contaminated site). The guideline
was developed in 2008 and revised in 2010 to improve the
understanding of how to implement the PAH soil quality
guidelines. A detailed scientific supporting document is
also available (CCME 2010). CCME soil quality
guidelines for naphthalene and benzo[a]pyrene were
previously developed in 1997. These 2010 values
supersede the 1997 guidelines.

Background Information

Much of the scientific, regulatory, and public interest in
PAHs is based on the potential role of these substances as
cancer-causing agents. This set of Canadian soil quality
guidelines specifically addresses existing management
gaps for PAH-contaminated soils in Canada where there is
concern about human health risks associated with
exposure to potentially carcinogenic PAHs such as
benzo[a]pyrene and other PAHs with similar modes of
action but of different potency, or concern about
ecological non-cancer effects of the broader suite of
unsubstituted PAHs.
The unsubstituted PAHs that are known or strongly
suspected to act as carcinogens in humans and other
mammals include:










The contamination of soil by polycyclic aromatic
hydrocarbons (PAHs) is widespread in Canada due to the
near ubiquitous nature of its major sources: namely, the
release of various petroleum hydrocarbon or coal-derived
products and the production of PAHs through a variety of
combustion processes/types such as vehicle exhaust or a
wide variety of industrial processes.
PAHs are a group of complex hydrocarbons comprised of
two or more fused benzenoid rings. In addition to
anthropogenic sources, some PAHs also occur naturally primarily as combustion byproducts or the modification of
plant-derived terpenoids and heterocyclic compounds.
Forest fires and volcanic eruptions are natural sources of
some PAHs.
In general, PAHs become increasingly less soluble in
water with an increasing number of benzenoid or other
rings, and increasing molecular weight. Naphthalene, a
two-ring PAH, is the most soluble, with an estimated
aqueous solubility of around 32 mg·L-1 at 25°C.
Indeno[1,2,3-c,d]pyrene, a six-ring PAH, has a much more
limited aqueous solubility at room temperature of
approximately 2.2 x 10-5 mg·L-1. Lower molecular weight
PAHs also tend to be more volatile (i.e., have a higher
vapour pressure) and more readily partition into air from
pure water (i.e., have a higher Henry’s Law constant). For
example, the vapour pressure and Henry’s Law constant
of naphthalene are 8.5 x 10-2 mm Hg and 4.83 x 10-4
atm·m3·mol-1, respectively, while those for indeno[1,2,3c,d]pyrene are 1.0 x 10-10 mm Hg and 1.6 x 10-6
atm·m3·mol-1, respectively.

POLYCYCLIC
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2010

benz[a]anthracene,
benzo[a]pyrene,
benzo[b]fluoranthene,
benzo[j]fluoranthene,
benzo[k]fluoranthene,
chrysene,
dibenz[a,h]anthracene,
benzo[g,h,i]perylene, and
indeno[1,2,3-c,d]pyrene.

In addition to the sixteen or so “unsubstituted” PAHs that
are commonly analyzed in North America in
environmental samples, there are hundreds of PAH
compounds containing nitrogen (N-) or sulfur (S-) atoms
within the carbon rings (heterocyclics), and/or with
various side chains attached to the aromatic ring structure.
Alkyl-substituted PAHs, in particular, are common
constituents of petrogenic (petroleum-derived) PAH
mixtures. Too little is currently known, however, about
the environmental fate and toxicity (either for humans or
various other living organisms) to enable development of
Canadian Soil Quality Guidelines for alkyl-PAHs.
PAHs are found in environmental samples almost always
as complex mixtures, with minor exceptions; for example,
in cases where naphthalene has been used and released in
the absence of other PAH compounds. This necessitates
some consideration of the risks and related
environmentally-acceptable soil thresholds of the entire
suite of PAHs present, not just of individual PAHs. Any
possible approach for dealing with environmental risks of
mixtures involves a number of trade-offs in terms of the
ability of the approach to account for compositional
variability across sites; toxicological variability across

Canadian Environmental Quality Guidelines
Canadian Council of Ministers of the Environment, 2008, revised 2010

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Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health

Figure 1. How to apply Canadian Soil Quality Guidelines for PAHs at a contaminated site.
There is no single Canadian Soil Quality Guideline that will protect both human and environmental health from all PAHs. To ensure that both
human and ecological receptors are protected, the following process must be followed (do Steps, 1 , 2 and 3)

For the protection of Human Health from:

carcinogenic effects of
PAHs;
benz[a]anthracene
benzo[a]pyrene
benzo[b+j+k]fluoranthene
benzo[g,h,i]perylene
chrysene
dibenz[a,h]anthracene
indeno[1,2,3-c,d]pyrene

do

&
Step 1
Calculate a Benzo[a]pyrene
Total Potency Equivalents
(B[a]P TPE) to ensure that
humans are protected from
direct contact with
contaminated soil

For the protection of Environmental Health from:

non-carcinogenic effects of PAHs (i.e.
not evaluated based on carcinogenicity);
anthracene
acenaphthene
acenaphthylene
fluoranthene
fluorene
naphthalene
phenanthrene
pyrene
Protection of human health from noncarcinogenic effects of PAHs was not
assessed; consult guidelines from other
jurisdictions for protection.

Step 2
Calculate the Index of
Additive Cancer Risk (IACR)
to ensure that potable water
resources are protected

non-carcinogenic effects of PAHs
(i.e. not evaluated based on
carcinogenicity);
anthracene
acenaphthene
acenaphthylene
benz[a]anthracene
benzo[a]pyrene
benzo[b]fluoranthene
benzo[k]fluoranthene
chrysene
dibenz[a,h]anthracene
fluoranthene
fluorene
indeno[1,2,3-c,d]pyrene
naphthalene
phenanthrene
pyrene
do

Step 3
Compare PAHs individually to the appropriate
environmental Soil Quality Guideline which were
developed based on non-carcinogenic effects.

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 Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health

PAHs

Table 1: Soil Quality Guidelines for Carcinogenic and Other PAHs (mg·kg-1)
IMPORTANT NOTE (1): Assess the hazard to human health from carcinogenic effects of PAHs by doing steps 1 and 2.
Assess the hazard to environmental health from non-carcinogenic effects of PAHs by doing step 3 (see Figure 1 and 2, and
factsheet text for more detail).
IMPORTANT NOTE (2): For soil contaminated with coal tar or creosote mixtures, the calculated Benzo[a]pyrene Total
Potency Equivalents (B[a]P TPE) concentration for soil samples should be multiplied by a safety factor of 3 prior to
comparison with the SQGDH to account for carcinogenic potential of alkylated and other PAHs present for which a Potency
Equivalence Factor (PEF) does not currently exist, but which are likely to contribute to mixture carcinogenic potential.
Land Use
Agricultural
Residential/
Commercial
Industrial
Parkland
Guideline – see table caption IMPORTANT NOTE (1)

Step

1
2

Human health guidelines based on carcinogenic effects of PAHs (see footnote c or d for carcinogenic PAHs)
0.6 B[a]P TPEc 0.6 B[a]P TPEc
0.6 B[a]P TPEc
0.6 B[a]P TPEc
Direct contact (SQGDH) – 10-6 a
-5 b
c
c
c
5.3 B[a]P TPE
5.3 B[a]P TPE
5.3 B[a]P TPE
5.3 B[a]P TPEc
Direct contact (SQGDH) – 10
d
d
d
IACR≤1.0
IACR≤1.0
IACR≤1.0
IACR≤1.0d
Protection of potable water (SQGPW)
Environmental health guidelines based on non-carcinogenic effects of PAHs
(do not use these values to protect humans; for carcinogenic PAHs consult the Human health guidelines above;
to protect humans from non-carcinogenic effects of PAHs consult guidelines from other jurisdictions; if a PAH
displays both cancer and non-cancer effects to humans, protect human health based on the threat from cancer)
2.5
2.5
32
32
Anthracene (SQGE)
20
20
72
72
Benzo[a]pyrene (SQGE)
Fluoranthene (SQGE)
50
50
180
180
0.013e
0.013e
0.013e
Naphthalene
0.013e
0.046e
0.046e
0.046e
Phenanthrene
0.046e
Benz[a]anthracene (CCME 1991)
0.1
1
10
10
0.1
1
10
10
Benzo[b]fluoranthenef (CCME 1991)
0.1
1
10
10
Benzo[k]fluoranthenef (CCME 1991)
0.1
1
10
10
Benzo[b+j+k]fluoranthenef
Dibenz[a,h]anthracene (CCME 1991)
0.1
1
10
10
Indeno[1,2,3-c,d]pyrene (CCME 1991)
0.1
1
10
10
Pyrene (CCME 1991)
0.1
10
100
100

3

Notes: SQGDH = human health-based soil quality guideline for direct contact; SQGE = soil quality guideline for environmental health; SQGPW = soil quality
guideline for the protection of potable water.
a
SQG based on an incremental lifetime cancer risk (ILCR) of 1 in 1,000,000 (10-6).
b
SQG based on an incremental lifetime cancer risk (ILCR) of 1 in 100,000 (10-5).
c
B[a]P TPE = Benzo[a]pyrene Total Potency Equivalents, which is the sum of estimated cancer potency relative to B[a]P for all potentially carcinogenic
unsubstituted PAHs. The B[a]P TPE for a soil sample is calculated by multiplying the concentration of each PAH in the sample by its B[a]P Potency
Equivalence Factor (PEF), given below, and summing the products (see Figure 2 for B[a]P TPE example calculation including PAH mixtures found in
coal tar or creosote).
B[a]P Potency Equivalence Factors:
Benz[a]anthracene
0.1
Benzo[g,h,i]perylene
0.01
Indeno[1,2,3-c,d]pyrene
0.1
Benzo[a]pyrene
1
Chrysene
0.01
Benzo[b+j+k]fluoranthene
0.1
Dibenz[a,h]anthracene
1
d
The Index of Additive Cancer Risk (IACR) assesses potential threats to potable groundwater water quality from leaching of carcinogenic PAH mixtures
from soil. The IACR is calculated by dividing the soil concentration (numerator) of each carcinogenic PAH by its soil quality guideline for protection of
potable water component value (denominator) to calculate a hazard index for each PAH, and then summing the hazard indices for the entire PAH mixture,
as follows (see Figure 2 for IACR example calculation):
IACR 

[ Benz ( a ) anthracene ] [ Benzo ( b  j  k ) fluoranthe ne ] [ Benzo ( g,h,i ) perylene ] [Benzo(a) pyrene] [Chrysene] [Dibenz(a,h)anthracene] [Indeno(1,2,3 c, d)pyrene]






2.7 mg  kg1
0.37 mg kg1
2.1mg kg1
0.23 mg kg1
0.33 mg  kg 1
0.16 mg  kg 1
6.8 mg  kg 1

e

This value is the Soil Quality Guideline for the Protection of Freshwater Life. Users may wish to consider the application, on a site-specific basis, of this
value where potential impacts to nearby surface waters are a concern (the value may be less than the common limit of detection in some jurisdictions;
contact jurisdiction for guidance). If impact to surface water is not a concern, it is recommended to revert to the 1997 provisional SQGE for naphthalene
and the 1991 Interim Soil Quality Criteria for phenanthrene (see Table 2).
f
Resolution between benzo[b]fluoranthene and benzo[k]fluoranthene gas chromatograph peaks may be difficult to achieve. When these two PAHs cannot
be reported separately, report them as the sum of benzo[b+j+k]fluoranthene and compare this value to the guideline for the combined 3 isomers.

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Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health

different taxa and soil types; and the possibility of nonadditive effects (synergistic or antagonistic interactions,
for example) of individual constituents in the mixture.

Behaviour and Effects in Biota

Developing soil quality guidelines for PAHs is
particularly challenging because there is likely to be
more than one toxicological mode of action in an
exposed organism, and the causal linkages between
exposure and actual effect at the whole organism level
are complex and likely to involve many intermediate
steps. The reader is encouraged to read the detailed
scientific rationale for the development of these PAH
soil quality guidelines (CCME 2008a) to better
understand the inherent assumptions and limitations.

Considerable scientific information is available on the
role of microbes in the environmental biodegradation of
PAHs, and on factors that influence microbial uptake
and degradation rates. Total microbial abundance and
biomass in soil can increase at some sites owing to the
ability of heterotrophic microbial consortia to utilize the
PAHs as an energy source, either alone or through cometabolism with other substances. One aspect of PAH
fate and effects that is often overlooked is the potential
risks at a contaminated site associated with the presence
of various microbial metabolites, such as dihydroxyPAH.

Microbial Processes

Environmental Fate and Behaviour in Soil

Very few studies have been carried out on the tendency
of individual PAHs or PAH-containing mixtures to
adversely affect the ability of naturally-occurring mixed
microbial communities to participate in the cycling
within the ecosystem of energy, carbon, nitrogen,
sulphur, phosphorus, and other macro- or
micronutrients.
PAHs in soils at individual
concentrations in the low parts-per-million range have
the potential to affect microbially-mediated functional
processes such as nitrification rates (Sverdrup et al.
2002a).

PAHs are relatively hydrophobic organic substances
(WHO/IPCS 1998). The tendency of PAHs to partition in
organic matter, onto particle surfaces, and into
biological lipids (and out of aqueous environmental
compartments such as groundwater) generally increases
with an increase in the number of benzenoid rings in the
aromatic ring structure (from 2 rings for naphthalene to
6 rings for benzo[g,h,i]perylene). Overall, the
unsubstituted PAHs occur along a spectrum of
hydrophobicity and lipophilicity, from naphthalene with
an octanol-water partition coefficient (Kow) of
approximately 2 x 103 to benzo[g,h,i]perylene with a
Kow of 4 x 106. There are approximately three to six
orders of magnitude difference between naphthalene and
benzo[g,h,i]perylene in aqueous solubility, tendency to
partition from hydrophobic organic matter into water,
vapour pressure at room temperature, and tendency to
partition between water and air (Henry’s Law Constant).

Terrestrial Plants
Limited data are available on the toxicity to plants of
PAHs in soils. Soil concentrations of individual PAHs
that have been associated with reduced plant growth are
in the range of approximately 30 to >2,000 mg·kg-1. The
available information, however, is generally limited to
commonly tested agronomic species. Further, for each
individual PAH there are generally insufficient data for
enough plant species to confidently construct a plant
sensitivity distribution; for many PAHs, no
phytotoxicity data exist.

The most important fate processes in soils, especially for
the higher molecular weight PAHs, are adsorption and
biodegradation. These PAHs remain tightly sorbed to
soils, and especially the five- to six-ringed PAHs may
exhibit a very limited bioavailability to terrestrial
organisms based on soil contact or to aquatic organisms
based on groundwater-mediated transfer.

Plants exhibit very limited ability to accumulate PAHs
from soils, and to translocate PAHs from root tissue into
aboveground biomass (Simonich and Hites 1995). Low
molecular weight PAHs (i.e., with two, three or four
rings) may be taken up by roots and translocated within
the plant, but do not appear to accumulate or magnify in
concentration relative to concentrations in the soil (EPRI
1992). High molecular weight PAHs (i.e., five or more
rings) may sorb to plant roots, but are not expected to
translocate or accumulate within the plant (EPRI 1992).
Risks to herbivores, therefore, from PAH uptake into
plant tissue are likely to be very low relative to the risks
associated with the incidental ingestion of soil.

Microbial degradation of PAHs in the soil environment
is generally the most important process accounting for
intermediate to long-term changes in substance levels
over time (USEPA 1990; Wild et al. 1991). Resistance
to microbial degradation in either soils or water tends to
increase with the molecular weight and number of rings,
as well. Whereas naphthalene tends to be readily
degraded in most situations, PAHs with four, five, or six
rings tends to be degraded much more slowly. In
general, biodegradation in an aerobic environment
occurs much more rapidly than in an anaerobic
environment (Neff 1979).
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 Canadian Soil Quality Guidelines for the
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Terrestrial Invertebrates

understanding of human health risks. A major emphasis
of available research has been on cancer-type effects.

One of the primary modes of toxicity of PAHs to soil
invertebrates, based on direct exposure in the soil
environment, is non-polar narcosis; i.e., epidermal
uptake of PAHs from soil pore water and/or dietary
intake and partitioning into body lipid (Sverdrup et al.
2002b). More specific modes of PAH toxicity cannot be
discounted, however.

Biochemical stress responses and biomarkers of PAH
exposure (e.g., hydroxypyrene in blood and urine) have
been examined in a limited number of wildlife species,
but the relevance of such data for predicting organism
and population fitness has yet to be determined.
Possible effects of various PAHs on exposed livestock
and wildlife species include but are not limited to
mortality,
growth,
reproductive
impairment,
teratogenesis, endocrine disruption, liver and kidney
damage,
neurobehavioural
changes,
altered
thermoregulatory ability, and cancer induction.

Reproductive impairment in most soil invertebrates
chronically exposed to PAHs or other contaminants
tends to occur at much lower soil concentrations than
acute or sub-chronic mortality. Most soil invertebrates
are well adapted to short periods of stress (e.g., during
periods of extreme cold or desiccation) and therefore
have a potential to use physiological and/or behavioural
stressor avoidance mechanisms.
However, such
mechanisms are typically accompanied by periods of
non-feeding so that long-term survival, and - more
specifically - fecundity, may be adversely affected.
Tests on PAH-contaminated soils based on short-term
mortality to earthworms, collembolans, or other soil
invertebrate taxa may under-predict the true risks to soil
invertebrate communities.

There is an absence in the scientific literature of
observational data from chronic as opposed to subchronic or acute exposures, detailed wildlife
epidemiological studies, or multi-generational studies.
Some indirect information is available on PAH toxicity
to wildlife based on the exposures in the laboratory to
whole crude oil, or in the field following large scale
accidental spills of crude oil. Effects of crude oil on
mallard ducks, American kestrels, and herring gulls
have been examined. These studies are of limited value,
however, in assessing the risks of PAH-contaminated
soils.

Given that uptake into lipids from the soil environment
is likely to be a major factor for determining subsequent
toxicological responses in soil invertebrates, the
organic-carbon water partition co-efficient of the
individual PAHs is likely to directly influence the soil
concentration at which adverse effects would be
observed.

A full summary of the available toxicity data for various
PAHs on mammalian and avian species is provided in
CCME (2008a).

As for all hydrophobic organic contaminants, the
bioavailability and subsequent toxicity of PAHs to soil
invertebrates exhibits high variability across different
soil types. Further, there is a limited ability to predict the
degree of toxicity as an alternative to using laboratory
toxicity tests to measure it.

Human and Experimental Animal Health
Effects
Many major reviews of human cancer and other risks
from PAHs have been completed within the last decade
(WHO/IPCS 1998; ATSDR 1995; Boström et al. 2002;
WHO 2003; WHO/IPCS 2004; others). One of the
major drivers for the large degree of scientific and
regulatory concern is based on the presence of PAHs in
urban air particulates, and associated risks of inhalation
exposures in human populations.

Toxicity data for various earthworm and springtail
species were available for individual PAHs. For a full
summary, refer to CCME (2008a).

Livestock and Wildlife

Total daily PAH intake for humans for the general
American population was estimated by Santodonato et
al. (1981) to vary from 0.2 to about 20 g·day-1,
excluding those individuals who are also occupationally
exposed. The general population is primarily exposed
via consumption of food and as a result of cigarette
smoking. Charbroiled grilling and smoked meats may be
a substantial source of PAH exposure in some human
populations. Depending on an individual’s lifestyle, the

One of the major knowledge gaps in PAH ecotoxicology
is in the area of effects on terrestrial vertebrate fauna,
including adult life-stages of amphibians, reptiles, birds,
and small to large mammalian herbivores, omnivores,
and carnivores. The current understanding of potential
risks of PAHs to livestock or wildlife is based almost
entirely on laboratory rodent studies, which have been
conducted primarily in support of a greater
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Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health

life-long cumulative intake (i.e., over 70 years or
greater) of benzo[a]pyrene for non-occupationally
exposed humans may add up to 29 mg, integrating
respiratory,
gastrointestinal
and
percutaneous
absorption.

Limited attempts to validate B[a]P relative potency
schemes have suggested a poor relationship between the
predicted and observed carcinogenicity of certain PAHcontaining mixtures, notably coal tar and creosote. The
tendency of benzo[a]pyrene relative potency schemes to
under-estimate coal tar carcinogenicity might be due to
the presence of unaccounted for carcinogens in the
mixture. In particular, Harvey et al. (2000) and Koganti
et al. (2001) found that 7H-benzo[c]fluorene, a major
constituent of coal tars, strongly induced DNA-adduct
formation. Therefore, the use of relative potency
schemes may under-predict the severity of cancer risks
for coal tar and creosote.

The emphasis herein for human health effects is on
cancer endpoints for those PAHs with known or
expected carcinogenic potential. There is sufficient
scientific information on the mechanisms of PAHinduced genotoxicity and carcinogenicity based on in
vitro (mammalian cell culture and bacterial culture) and
in vivo (laboratory rodent) studies to conclude that the
PAHs considered herein are known or potential
carcinogens. It is recommended that Health Canada be
contacted directly for guidance regarding PAHs that are
not covered by this guidance.

Guideline Derivation
Canadian soil quality guidelines are derived for different
land uses following the process outlined in CCME
(2006) using different receptors and exposure scenarios
for each land use. Detailed derivations for these soil
quality guidelines are provided in CCME (2008a).

PAHs have limited ability to bind to DNA and cause
mutations until they are converted to more potent
intermediates (especially PAH diol-epoxides) by
cytochrome P450 oxidases (CYP1A1-type enzymes).
PAHs with two or three aromatic rings (for example,
naphthalene, acenaphthene, acenaphthylene, fluorene,
anthracene, phenanthrene) have been consistently shown
to have very limited or no tendency to bind to the Ahreceptor, and to induce CYP enzymes such as EROD
(ethoxyresorufin-O-deethylase) (Bosveld et al. 2002). It
is suggested that these lighter molecular weight PAHs
do not meet the structural requirements for having an
affinity to bind to the Ah-receptor. Bosveld and other
researchers (reviewed in Bosveld et al. 2002) found that
benzo[k]fluoranthene was among the most potent
inducers of EROD or reporter gene activity in vitro.

Soil Quality Guidelines for Environmental Health
Environmental soil quality guidelines (SQGE) are based
on soil contact using data from toxicity studies on plants
and invertebrates. In the case of agricultural use, soil
and food ingestion toxicity data for mammalian and
avian species are included. To provide a broader scope
of protection, a nutrient and energy cycling check is
calculated where the data permit. For commercial and
industrial land uses, an off-site migration check is also
calculated.
There were insufficient soil contact data for the PAHs,
acenaphthene,
acenaphthylene,
benz[a]anthracene,
benzo[b]fluoranthene,
benzo[k]fluoranthene,
benzo[g,h,i]perylene, chrysene, dibenz[a,h]anthracene,
fluorene, indeno[1,2,3-c,d]pyrene, phenanthrene, and
pyrene, using either the preferred weight-of-evidence
method (CCME 2006) or secondary derivation methods.
Direct contact soil quality guidelines were calculated for
fluoranthene and benzo[a]pyrene using a weight-ofevidence approach, and for anthracene based on
selection of the lowest LOEC for agricultural and
residential/parkland land uses and based on the
geometric mean value of three suitable LOEC values for
commercial and industrial land uses (Table 2).

The mechanisms of PAH carcinogenesis are described
in greater detail in CCME (2008a).
A major challenge in assessing the cancer risks of
human exposures to PAH-containing mixtures is that no
whole organism sub-chronic or chronic studies have
been completed on the carcinogenicity of individual
PAHs other than benzo[a]pyrene (B[a]P). It is therefore
not possible to confidently and directly develop cancer
slope factors for the potentially carcinogenic PAHs
other than B[a]P. Instead, the evaluation of human
cancer risks internationally has tended to be based on
the use of B[a]P relative potencies, derived from whole
animal studies with dermal, implantation, inhalation,
oral or other exposure methods. The tumour incidence
from studies of B[a]P is compared with incidence for the
other PAHs under the same or similar conditions in
order to estimate the cancer potency of the other PAHs
relative to B[a]P.

Given the current limitations of our scientific
understanding, the inability to calculate direct soil
contact soil quality guidelines for the majority of the
PAHs may be of little practical significance to the
overall achievement of environmental protection goals
at Canadian contaminated sites. The direct soil contact
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For protection of the non-human environment, soil
quality guidelines recommended for agricultural,
residential/ parkland, commercial and industrial sites are
outlined in Table 2.

soil quality standards recently promulgated as the
Canada-Wide Standards for Petroleum Hydrocarbons
(PHC CWS) might account for contributions to toxic
responses of soil invertebrates and plants for several of
these unsubstituted PAHs as well as alkyl-substituted
forms. The PHC CWS were derived using newly
generated ecotoxicity data on a fractioned Federated
crude oil in a standardized (OECD) soil type as well as a
relatively fine-grained Chernozem loam soil. No
corrections were made for the presence of PAHs in the
petroleum mixtures.

Soil Quality Guidelines for Human Health
Human health soil quality guidelines (SQGHH) for nonthreshold (carcinogenic) contaminants require the
development of soil quality guidelines that employ a
critical risk-specific dose (RsD), based on incremental
lifetime cancer risks (ILCRs) from exposure to PAHcontaminated soil. For all land uses, the adult was
chosen as the receptor when considering lifetime cancer
risk. For non-threshold contaminants, human exposure
should be reduced to the maximum extent possible.
Some jurisdictions in Canada have adopted an
“essentially negligible” ILCR of 10-5 (or 1 in 100,000)
for managing risks of carcinogenic contaminants, while
other jurisdictions use an ILCR of 10-6 (or 1 in
1,000,000). In light of this, soil quality guideline
calculations were undertaken using both a 10-5 and 10-6
ILCR. Both of these incremental risks above background
fall within the range considered to be “essentially
negligible” in the derivation of MACs (Maximum
Acceptable Concentrations) for carcinogenic chemicals
in drinking water (Health and Welfare Canada 1989).

More work is required, however, to establish the
relevance of the PHC CWS to managing PAH risks to
soil organisms. Those with responsibility for
contaminated sites investigation and management may
need to look beyond the generic guidance for protecting
soil ecological functioning if there exists a contaminant
mixture which exhibits very high PAH concentrations
relative to other petroleum-derived hydrocarbons.
Soil quality guidelines for the protection of freshwater
life (SQGFL) were derived using the CCME (2006)
protocol for all PAHs for which CCME water quality
guidelines for the protection of aquatic life exist
(naphthalene, acenaphthene, fluorene, anthracene,
phenanthrene, pyrene, fluoranthene benz[a]anthracene,
and benzo[a]pyrene). For the remaining PAHs, an
attempt was made to calculate SQGFL values by
assuming a narcosis-type mode of action in the aquatic
receiving environment and a Critical Body Residuebased threshold for chronic effects equivalent to 3.0
mmol PAH·kg-1 lipid (Di Toro et al. 2000). This
derivation procedure is beyond the guidance provided in
CCME (2006), but is virtually identical to the procedure
used in the derivation of aquatic life protective soil
concentration thresholds for the PHC CWS (CCME
2008b). Only one additional SQGFL was determined
using the critical body residue approach, and that was
for acenaphthylene.

Various check mechanisms are applied, if relevant, to
the preliminary human health soil quality guidelines in
order to provide them with a broader scope of
protection, such as the potential to adversely impact
humans through the consumption of groundwater,
agricultural crops and livestock.
A soil quality guideline for the protection of potable
water (SQGPW) was derived for potentially carcinogenic
PAHs. An off-site migration check was not carried out,
since the preliminary SQGHH for commercial and
industrial land uses were the same as for the more
sensitive land uses. Nor was a produce, meat and milk
check carried out, since PAHs exhibit very limited
potential for food-web mediated transfer.

For agricultural and residential/parkland land uses, soil
and food ingestion by cows as a representative livestock
species, and mule deer, meadow voles and American
robins as representative wildlife species, were
considered. For most PAHs, only a provisional soil and
food ingestion guideline (SQGI) could be derived, due to
lack of sufficient data (with the exception of
naphthalene for which a full SQGI was derived) (Table
2). The SQGI values presented in Table 2 are for the
protection of secondary consumers (based on soil and
food ingestion for American robins). SQGIs for the
protection of primary consumers are orders of
magnitude higher (see CCME 2008a for SQGIs for
primary consumers). Note that the provisional SQGI
values were not used in determining the overall SQGE.

For protection against cancer risks in humans, it is
recommended that the benzo[a]pyrene Total Potency
Equivalents (B[a]P TPE) in soil be established at a
threshold value of 0.6 mg·kg-1 for an ILCR of 10-6 and
5.3 mg·kg-1 for an ILCR of 10-5 for all land uses.
In 1996, Health Canada developed a human health
protective soil quality guideline for benzo[a]pyrene with
a value of 1.5 mg·kg-1 (CCME 1999). Of all possible
human exposure pathways, the 1996 guideline
7

 POLYCYCLIC AROMATIC
HYDROCARBONS

Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health

accounted only for the oral exposure route, and was
based on a risk-specific dose (RsD) of 0.000435 g
benzo[a]pyrene·kg bw-1·day-1 for an incremental cancer
risk of 10-6, based in turn on a cancer slope factor of 2.3
(mg·kg-1·day-1)-1.

uncertainty factor should be applied to soils
contaminated with coal tar or creosote to account for the
risks associated with other potentially carcinogenic
PAHs present, but not included in the PEF scheme. In
practice, the B[a]P TPE concentration for such site soils
should be multiplied by a factor of three (3) prior to
comparison with the SQGDH. In cases where site
information is insufficient to determine whether PAH
contamination has resulted from a coal tar or creosote
source, the uncertainty factor should be applied.

This calculation was revised herein to also account for
possible dermal and particulate inhalation uptake of
benzo[a]pyrene from site soils. The critical study (Neal
and Rigdon 1967) consulted by Health Canada (1996)
and adopted herein used an orally administered, not
absorbed, dose.
A relative absorption factor for
inhalation and ingestion is assumed to be 100%, by
default. This factor assumes that the bioavailability of
PAHs in soil will be the same as the bioavailability of
PAHs in the food administered to the test animals in the
critical study used to derive the risk specific dose. The
magnitude of dermal absorption is not expected to be
similar to oral absorption. Therefore a dermal absorption
factor of 34% was derived based on the available
literature.

The above-listed PEFs were also used to produce B[a]P
equivalent
values
in
potable
water
for
benz[a]anthracene, benzo[b+j+k]fluoranthene, chrysene,
benzo[g,h,i]perylene,
dibenz[a,h]anthracene, and
indeno[1,2,3-c,d]pyrene (CCME 2008a). The PAHs
were treated individually, since different compounds
within PAH mixtures would be expected to exhibit
differing potential for groundwater-mediated transport
(i.e., based on orders of magnitude difference in organic
carbon-water (KOC) partition co-efficients). Therefore,
soil-to-potable water-based risks of individual PAHs
were modeled to derive soil quality guideline for the
protection of potable water (SQGPW) component values
for individual carcinogenic PAHs. It should be noted
that the individual SQGPW component values are not
stand alone soil quality guidelines. Rather, each has
been incorporated into the “Index of Additive Cancer
Risks” (IACR) equation, to account for the combined
effects of individual PAHs in the mixture (Tables 1 and
2). The resulting IACR value is equivalent to a hazard
index and should not exceed a value of 1.0. Therefore,
the final SQGPW is expressed as IACR ≤ 1.

Shatkin et al. (2002) developed a fugacity model to
predict dermal uptake of benzo[a]pyrene from soil, and
compared the model predictions with nine experimental
data points, which agreed within a factor of two. An
upper bound estimate based on this study for dermal
absorption over a 24 h period is 34%, which is the
modeled mean plus one standard deviation.
The B[a]P TPE is calculated for potentially carcinogenic
PAHs by multiplying their concentrations in soil by the
following B[a]P Potency Equivalence Factors (B[a]P
PEFs) and summing the products.
B[a]P PEFs
Benz[a]anthracene
Benzo[a]pyrene
Benzo[b+j+k]fluoranthene
Chrysene
Benzo[g,h,i]perylene
Dibenz[a,h]anthracene
Indeno[1,2,3-c,d]pyrene

Although not specified in the CCME (2006) protocol, a
set of soil PAH threshold values was also calculated for
human health risks based on acute exposures of infants
potentially engaged in pica soil ingestion. The soil PAH
thresholds were calculated assuming short-term PAH
exposures only, via oral ingestion, and threshold
mechanisms of toxicity as opposed to non-threshold
(carcinogenic) ones. Toddlers (6 months to 4 years of
age) have been observed to engage in “pica” soil
ingestion. Per U.S. EPA guidance, it was assumed that a
child involved in pica soil ingestion may consume a
maximum of 5,000 mg soil·day-1. ATSDR (1995) did
not develop any acute oral Minimal Risk Levels (MRLs)
for PAHs due to the absence of guiding studies.
However, there are four ATSDR (1995) MRLs
developed for intermediate exposures (15 to 364 days):
acenaphthene: 0.6 mg·kg-1 day-1, anthracene: 10 mg·kg1
·day-1, fluoranthene: 0.4 mg·kg-1·day-1 and fluorene: 0.4
mg·kg-1·day-1. The calculated soil threshold values for
the four individual PAHs based on pica exposure in
infants were all greater than 1,000 mg·kg-1. Pica and
other types of acute exposure, therefore, are not deemed

0.1
1
0.1
0.01
0.01
1
0.1

The cancer risk for the combined exposure to potentially
carcinogenic PAHs is assumed to be additive, but this is
a source of uncertainty. The soil B[a]P TPE is intended
to ensure that incremental lifetime cancer risk from soil
ingestion, inhalation and dermal exposure does not
exceed 1 x 10-6 or 1 x 10-5. Initially, an uncertainty
factor was considered for application in deriving the
B[a]P TPE, since limited attempts to validate B[a]P
relative potency schemes have shown a potential for the
under-prediction of human cancer risks. It was felt that
an uncertainty factor was not justified for most
contaminant mixture types.
However, a 3-fold
8

 Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health

POLYCYCLIC AROMATIC
HYDROCARBONS

to be of concern for these unsubstituted PAHs based on
the currently available toxicological data.

It should be noted that, although petroleum
hydrocarbons (PHCs) contain PAHs, the Canada-wide
Standard for Petroleum Hydrocarbons (CCME, 2008)
was not developed to address the issue of
carcinogenicity. Remediation of contaminated soils to
meet the PHC standards will not necessarily mean that
the PAH soil quality guidelines for human health
protection will be met, and vice versa.

Soil Quality Guidelines for Carcinogenic
and Other PAHs
The soil quality guidelines for PAHs are intended to be
protective of both environmental and human health. In
contrast to normal practice where the lower of either the
human health or environmental values drive the final
soil quality guideline, the recommendation is that soil
samples be assessed for carcinogenic effects to humans
and non-carcinogenic effects to ecological receptors
separately, by (1) Converting to B[a]P equivalents for
comparison with the SQGDH, (2) Calculating an IACR
and comparing the value to 1, and (3) Comparing soil
sample concentrations for individual PAHs against the
most conservative guideline developed based on noncarcinogenic effects for that land use (Table 1 and 2).

SQG for freshwater life protection (Table 2) were
derived for the majority of commonly analyzed,
unsubstituted PAHs, and tend to be much lower than
other preliminary SQG for either human health or
environmental protection. They were nonetheless
determined to be greater than expected background soil
PAH concentrations in other than highly urbanized and
industrialized regions of Canada. The SQGFL are not
reflected in the overall SQG (except for naphthalene and
phenanthrene), but users may wish to consider their
application on a site-specific basis where potential
impacts on nearby surface water are a concern.

References
Harvey, R.G., L.S. Goldstein, T.A. Roy, F.J. Zhang, A. Koganti, R.
Singh, K. Rozett, N. Modi, and E.H. Weyand. 2000. 7Hbenzo[c]fluorene: a major DNA adduct-forming component of
coal tar. Carcinogenesis 21: 1601-1609.
Health Canada. 1996. Canadian soil quality guidelines for
contaminated sites. Human health effects: Benzo[a]pyrene. Final
report. Prepared for the National Contaminated Sites
Remediation Program, Canadian Council of Ministers of the
Environment.
Health and Welfare Canada. 1989. Derivation of Maximum
Acceptable Concentrations and Aesthetic Objectives for
Chemicals in Drinking Water. In: Guidelines for Canadian
Drinking Water Quality - Supporting Documentation. Prepared
by the Federal-Provincial Subcommittee on Drinking Water of
the Federal-Provincial Advisory Committee on Environmental
and Occupational Health. Ottawa.
Koganti, A., R. Singh, B.L. Ma, and E.H. Weyand.
2001.
Comparative analysis of PAH:DNA adducts formed in the lung
of mice exposed to neat coal tar and soils contaminated with coal
tar. Environ. Sci. Technol. 35(13): 2704-2709.
Neal, J. and R.H. Rigdon. 1967. Gastric tumors in mice fed
benzo[a]pyrene: A quantitative study. Tex. Rep. Biol. Med.
25:553-557.
Neff, J.M. 1979. Polycyclic Aromatic Hydrocarbons in the Aquatic
Environment. Sources, Fates and Biological Effects, Applied
Science Publishers Ltd., Essex, England, 262 p.
Santodonato, J., P. Howard, and D. Basu. 1981. Health and Ecological
Assessment of Polynuclear Aromatic Hydrocarbons. J. Environ.
Pathol. Toxicol 5:1-36.
Shatkin, J.A., M. Wagle, S. Kent and C.A. Menzies. 2002.
Development of a biokinetic model to evaluate dermal
absorption of polycyclic aromatic hydrocarbons from soil.
Human Ecol. Risk Assess 8: 713-734.
Simonich, S.L., and R.A. Hites. 1995. Organic pollutant accumulation
in vegetation. (Critical Review). Environ. Sci. Technol. 29(12):
2905-2914.
Sverdrup, L. E., F. Ekelund, P.H. Krogh, T. Nielsen, and K. Johnsen.
2002a. Soil microbial toxicity of eight polycyclic aromatic

ATSDR (Agency for Toxic Substances and Disease Registry). 1995.
Toxicological Profile for Polycyclic Aromatic Hydrocarbons.
ATSDR/TP-95-20. U.S. Department of Health and Human
Services, Public Health Service, ATSDR. Atlanta, GA.
Boström, C.-E., P. Gerde, A, Hanberg, B. Jernström, C. Johansson, T.
Kyrklund, A. Rannug, M. Törnqvist, K. Victorin and R.
Westerholm. 2002. Cancer risk assessment, indicators and
guidelines for polycyclic aromatic hydrocarbons in ambient air.
Environ. Health Perspect. 110 (Suppl 3):451-489.
Bosveld, A.T.C., A.A.F. de Bie, N.W. van den Brink, H. Jongepier,
and A.V. Klomp. 2002. In vitro EROD induction equivalency
factors for the 10 PAHs generally monitored in risk assessment
studies in the Netherlands. Chemosphere 49: 75-83.
CCME (Canadian Council of Ministers of the Environment). 1991.
Interim Canadian environmental quality criteria for contaminated
sites. CCME, Winnipeg.
———. 1999. Canadian environmental quality guidelines, 1999,
Canadian Council of Ministers of the Environment, Winnipeg.
———. 2006. A protocol for the derivation of environmental and
human health soil quality guidelines (update). Canadian Council
of Ministers of the Environment, Winnipeg. 210 pages.
———. 2008. Canada-wide standards for petroleum hydrocarbons
(PHC) in soil: Scientific rationale – Supporting technical
document. (update of 2000 version) CCME, Winnipeg.
______ 2008b. Canada-wide standards for petroleum hydrocarbons
(PHC) in soil: Scientific rationale – Supporting technical
document. (update of 2000 version) CCME, Winnipeg.
———. 2010. Canadian soil quality guidelines for potentially
carcinogenic and other PAHs: Scientific criteria document.
CCME, Winnipeg. 216 pages.
Di Toro, D.M., J.A. McGrath and D.J. Hansen. 2000. Technical basis
for narcotic chemicals and polycyclic aromatic hydrocarbon
criteria. I. Water and tissue. Environ Toxicol. Chem. 19: 19511970.
EPRI (Electric Power Research Institute), 1992. Uptake, translocation,
and accumulation of polycyclic aromatic hydrocarbons in
vegetation. EPRI TR-101651, Project 2879-10, Interim Report,
December 1992. Prepared by Oak Ridge National Laboratory.

9

 POLYCYCLIC AROMATIC
HYDROCARBONS

Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health
WHO/IPCS. 2004. Concise International Chemical Assessment
Document 62: Coal Tar Creosote. Internatinal Program on
Chemical Safety, United Nations Environmental Program, World
Health Organization, Geneva.
Wild, S.R., M.L. Berrow, and K.C. Jones. 1991. The persistence of
polynuclear aromatic hydrocarbons (PAH) in sewage sludge
amended agricultural soils. Environ. Pollut. 72: 141-157

compounds: Effects on nitrification, the genetic diversity of
bacteria, and the total number of protozoans. Environ. Toxicol.
Chem. 21:1644–1650.
Sverdrup, L.E., T. Nielsen, and P. H. Krogh. 2002b. Soil ecotoxicity of
polycyclic aromatic hydrocarbons in relation to soil sorption,
lipophilicity, and water solubility. Environ. Sci. Technol. 36:
2429-2435.
USEPA (United States Environmental Protection Agency). 1990.
Chemical Fate Rate Constants for SARA Section 113 Chemicals
and Superfund Health Evaluation Manual Chemicals, Office of
Toxic Substances, Washington, DC, 6-02-425.
WHO/IPCS. 1998. Environmental Health Criteria 202: Selected NonHeterocyclic Polycyclic Aromatic Hydrocarbon. International
Program on Chemical Safety, United Nations Environmental
Program, World Health Organization.
WHO. 2003. World Health Organization. Polynuclear aromatic
hydrocarbons in Drinking-water, Background document for
development of WHO Guidelines for Drinking-water Quality.
WHO/SDE/WSH/03.04/59.

10

 Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health

POLYCYCLIC AROMATIC
HYDROCARBONS

Environmental health guidelines/check values

Human health guidelines/check values

Table 2. Soil Quality Guidelines for Carcinogenic and Other PAHs (mg·kg-1)
IMPORTANT NOTE (1): There is no single final Soil Quality Guideline (SQGF) for any of the PAHs included in this
guideline that will protect both human and environmental health. To ensure that both human and ecological receptors are
protected, the user must (1) calculate a Benzo[a]pyrene Total Potency Equivalents (B[a]P TPE) to ensure that humans are
protected from direct contact with soil contaminated with carcinogenic PAHs, (2) calculate the Index of Additive Cancer
Risk (IACR) to ensure that potable water resources are protected from carcinogenic PAHs, and (3) consider all relevant
guidelines to protect ecological receptors from non-carcinogenic effects, in this table, for the land use in question.
IMPORTANT NOTE (2): For soil contaminated by coal tar or creosote mixtures, the calculated Benzo[a]pyrene Total
Potency Equivalents (B[a]P TPE) concentration for soil samples should be multiplied by a safety factor of 3 prior to
comparison with the SQGDH to account for carcinogenic potential of alkylated and other PAHs present for which a Potency
Equivalent Factor (PEF) does not currently exist, but which are likely to contribute to mixture carcinogenic potential.
Land Use
Agricultural
Residential/
Commercial
Industrial
Parkland
Guideline (SQGF)–see table caption, IMPORTANT NOTE 1
Human health guidelines/check values based on carcinogenic effects of PAHs
(potentially carcinogenic PAHs are benz[a]anthracene, benzo[a]pyrene, benzo[b+j+k]fluoranthenem,
benzo[g,h,i]perylene, chrysene, dibenz[a,h]anthracene, and indeno[1,2,3-c,d]pyrene)
SQGHH
Direct contacta (SQGDH) – ingestion,
inhalation, and dermal exposures
1×10-6 incremental lifetime cancer risk
1×10-5 incremental lifetime cancer risk
Protection of indoor air quality (SQGIAQ)
Off-site migration (SQGOM-HH)
Protection of potable water (SQGPW)
Produce, meat, and milk (SQGFI)

NC

NC

NC

NC

0.6 B[a]P TPEb
5.3 B[a]P TPEb
NC
IACR≤1.0c
NC

0.6 B[a]P TPEb
5.3 B[a]P TPEb
NC
IACR≤1.0c
NC

0.6 B[a]P TPEb
5.3 B[a]P TPEb
NC
NC
IACR≤1.0c
-

0.6 B[a]P TPEb
5.3 B[a]P TPEb
NC
NC
IACR≤1.0c
-

Environmental health guidelines/check values based on non-carcinogenic effects of PAHs
(do not use these values to protect humans; for carcinogenic PAHs consult the Human health guidelines above; to
protect humans from non-carcinogenic effects of PAHs consult guidelines from other jurisdictions; if a PAH displays
both cancer and non-cancer effects to humans, protect human health based on the threat from cancer)
Environmental health guideline values
for Acenaphthene
SQGEd
NC
NC
NC
NC
Soil contact (SQGSC)
NC
NC
NC
NC
Soil and food ingestion (SQGI)
21.5e
21.5e
f
g
Protection of freshwater life (SQGFL)
0.28
0.28g
0.28g
0.28g
Interim Soil Quality Criteria (CCME 1991)
no value
no value
no value
no value
Environmental health guideline values
for Acenaphthylene
SQGEd
NC
NC
NC
NC
Soil contact (SQGSC)
NC
NC
NC
NC
Soil and food ingestion (SQGI)
NC
NC
Protection of freshwater lifef (SQGFL)
320h
320h
320h
320h
Interim Soil Quality Criteria (CCME 1991)
no value
no value
no value
no value
Continued…

11

 POLYCYCLIC AROMATIC
HYDROCARBONS

Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health

Environmental health guidelines/check values

Agricultural
Environmental health guideline values
for Anthracene
SQGEd
Soil contact (SQGSC)
Soil and food ingestion (SQGI)
Protection of freshwater lifef (SQGFL)
Interim Soil Quality Criteria (CCME 1991)
Environmental health guideline values
for Benz[a]anthracene
SQGEd
Soil contact (SQGSC)
Soil and food ingestion (SQGI)
Protection of freshwater lifef (SQGFL)
Interim Soil Quality Criteria (CCME 1991)
Environmental health guideline values
for Benzo[a]pyrene
SQGEd
Soil contact (SQGSC)
Soil and food ingestion (SQGI)
Protection of freshwater lifef (SQGFL)
Provisional SQGE (CCME 1997)
Environmental health guideline values
for Benzo[b]fluoranthener
SQGEd
Soil contact (SQGSC)
Soil and food ingestion (SQGI)
Protection of freshwater lifef (SQGFL)
Interim Soil Quality Criteria (CCME 1991)
Environmental health guideline values
for Benzo[k]fluoranthener
SQGEd
Soil contact (SQGSC)
Soil and food ingestion (SQGI)
Protection of freshwater lifef (SQGFL)
Interim Soil Quality Criteria (CCME 1991)
Environmental health guideline values
for Benzo[g,h,i]perylene
SQGEd
Soil contact (SQGSC)
Soil and food ingestion (SQGI)
Protection of freshwater lifef (SQGFL)
Interim Soil Quality Criteria (CCME 1991)

Land Use
Residential/
Commercial
Parkland

Industrial

2.5p
2.5
61.5e
NAg,i
no value

2.5p
2.5
61.5e
NAg,i
no value

32p
32
NAg,i
no value

32p
32
NAg,i
no value

NC
NC
6.2e
NAg,i
0.1j

NC
NC
6.2e
NAg, i
1j

NC
NC
NAg, i
10 j

NC
NC
NAg, i
10 j

20k
20
0.6e
8800g
0.7

20k
20
0.6e
8800g
0.7

72k
72
8800g
1.4

72k
72
8800g
1.4

NC
NC
6.2e
NAh,i
0.1j

NC
NC
6.2e
NAh,i
1j

NC
NC
NAh,i
10 j

NC
NC
NAh,i
10 j

NC
NC
6.2e
NAh,i
0.1j

NC
NC
6.2e
NAh,i
1j

NC
NC
NAh,i
10 j

NC
NC
NAh,i
10 j

NC
NC
NC
NAh,i
no value

NC
NC
NC
NAh,i
no value

NC
NC
NAh,i
no value

NC
NC
NAh,i
no value
Continued...

12

 Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health

POLYCYCLIC AROMATIC
HYDROCARBONS

Environmental health guidelines/check values

Agricultural
Environmental health guideline values
for Chrysene
SQGEd
Soil contact (SQGSC)
Soil and food ingestion (SQGI)
Protection of freshwater lifef (SQGFL)
Interim Soil Quality Criteria (CCME 1991)
Environmental health guideline values
for Dibenz[a,h]anthracene
SQGEd
Soil contact (SQGSC)
Soil and food ingestion (SQGI)
Protection of freshwater lifef (SQGFL)
Interim Soil Quality Criteria (CCME 1991)
Environmental health guideline values
for Fluoranthene
SQGEd
Soil contact (SQGSC)
Soil and food ingestion (SQGI)
Protection of freshwater lifef (SQGFL)
Interim Soil Quality Criteria (CCME 1991)
Environmental health guideline values
for Fluorene
SQGEd
Soil contact (SQGSC)
Soil and food ingestion (SQGI)
Protection of freshwater lifef (SQGFL)
Interim Soil Quality Criteria (CCME 1991)
Environmental health guideline values
for Indeno[1,2,3-c,d]pyrene
SQGEd
Soil contact (SQGSC)
Soil and food ingestion (SQGI)
Protection of freshwater lifef (SQGFL)
Interim Soil Quality Criteria (CCME 1991)
Environmental health guideline values
for Naphthalene
SQGEd
Soil contact (SQGSC)
Soil and food ingestion (SQGI)
Protection of freshwater lifef (SQGFL)
Provisional SQGE (CCME 1997)
Environmental health guideline values
for Phenanthrene
SQGEd
Soil contact (SQGSC)
Soil and food ingestion (SQGI)
Protection of freshwater lifef (SQGFL)
Interim Soil Quality Criteria (CCME 1991)

Land Use
Residential/
Commercial
Parkland

Industrial

NC
NC
6.2e
NAh,i
no value

NC
NC
6.2e
NAh,i
no value

NC
NC
NAh,i
no value

NC
NC
NAh,i
no value

NC
NC
NC
NAh,i
0.1j

NC
NC
NC
NAh,i
1j

NC
NC
NAh,i
10 j

NC
NC
NAh,i
10 j

50p
50
15.4e
NAg,i
no value

50p
50
15.4e
NAg,i
no value

180p
180
NAg,i
no value

180p
180
NAg,i
no value

NC
NC
15.4e
0.25g
no value

NC
NC
15.4e
0.25g
no value

NC
NC
0.25g
no value

NC
NC
0.25g
no value

NC
NC
NC
NAh,i
0.1j

NC
NC
NC
NAh,i
1j

NC
NC
NAh,i
10 j

NC
NC
NAh,i
10 j

NC
NC
8.8
0.013g,l
0.6n

NC
NC
8.8
0.013g,l
0.6n

NC
NC
0.013g,l
22n

NC
NC
0.013g,l
22n

NC
NC
43.0e
0.046g,l
0.1o

NC
NC
43.0e
0.046g,l
5o

NC
NC
0.046g,l
50o

NC
NC
0.046g,l
50o
Continued…

13

 POLYCYCLIC AROMATIC
HYDROCARBONS

Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health

Environmental health guidelines/check values

Agricultural
Environmental health guideline values
for Pyrene
SQGEd
Soil contact (SQGSC)
Soil and food ingestion (SQGI)
Protection of freshwater lifef (SQGFL)
Interim Soil Quality Criteria (CCME 1991)
The following guidelines/check pathways
were evaluated for all PAHs appearing in
the environmental section
Livestock Watering (SQGLW)
Irrigation Water (SQGIR)
Nutrient and energy cycling check
(SQGNEC)
Off-site migration check (SQGOM-E)

Land Use
Residential/
Commercial
Parkland

Industrial

NC
NC
7.7e
NAg,i
0.1q

NC
NC
7.7e
NAg,i
10q

NC
NC
NAg,i
100q

NC
NC
NAg,i
100q

NC
NC
NC

NC

NC

NC

-

-

NC

NC

Notes: NA = not applicable; NC = not calculated; SQGE = soil quality guideline for environmental health; SQGHH = soil quality guideline for
human health; SQGI = soil quality guideline for protection of livestock and wildlife based on soil and food ingestion; SQGIR = soil quality guideline
for the protection of irrigation water; SQGIAQ = soil quality guideline for the protection of indoor air quality; SQGF = final soil quality guideline (for
protection of environmental and human health); SQGLW = soil quality guideline for protection of livestock based on water consumption; SQGNEC =
soil quality guideline check value for the protection of nutrient and energy cycling; SQGPW = soil quality guideline for the protection of potable
groundwater; SQGOM-E = soil quality guideline check value for off-site migration of soils in consideration of environmental health risks; SQGOM-HH
= soil quality guideline check value for off-site migration of soils in consideration of human health risks; SQGSC = soil quality guideline for soil
contact by soil-dependent organisms (e.g., plants and invertebrates). The dash indicates a guideline/check value that is not part of the exposure
scenario for this land use and therefore is not calculated.
a

b

c

IACR 

Guideline values for toddler pica soil ingestion have also been calculated for benzo[a]pyrene, acenaphthene, fluorene, anthracene and
fluoranthene, but are several orders of magnitude higher than the direct contact guidelines. For more details on the pica guidelines, refer to
section 7.1.4 of the scientific supporting document (CCME, 2008a).
B[a]P TPE = Benzo[a]pyrene Total Potency Equivalents, which is the sum of estimated cancer potency relative to B[a]P for all potentially
carcinogenic unsubstituted PAHs. The B[a]P TPE for a soil sample is calculated by multiplying the concentration of each PAH in the sample by
its B[a]P Potency Equivalence Factor (PEF), given below, and summing these products (see Figure 2 for B[a]P TPE example calculation
including PAH mixtures found in coal tar or creosote). B[a]P PEFs are order of magnitude estimates of carcinogenic potential and are based on
the World Health Organization (WHO/IPCS 1998) scheme, as follows:
Benz[a]anthracene
0.1
Benzo[g,h,i]perylene
0.01
Indeno[1,2,3-c,d]pyrene
0.1
Benzo[a]pyrene
1
Chrysene
0.01
Benzo[b+j+k]fluoranthene
0.1
Dibenz[a,h]anthracene
1
The Index of Additive Cancer Risk (IACR) assesses potential threats to potable groundwater water quality from leaching of carcinogenic PAH
mixtures from soil. The IACR is calculated by dividing the soil concentration (numerator) of each carcinogenic PAH by its soil quality guideline
for protection of potable water component value (denominator) to calculate a hazard index for each PAH, and then summing the hazard indices
for the entire PAH mixture, as follows (see Figure 2 for IACR example calculation):

[ Benz ( a ) anthracene ] [ Benzo ( b  j  k ) fluoranthe ne ] [ Benzo ( g,h,i ) perylene ] [Benzo(a) pyrene] [Chrysene] [Dibenz(a,h)anthracene] [Indeno(1,2,3 c, d)pyrene]






2.7 mg  kg1
0.37 mg kg1
2.1mg kg1
0.23 mg kg1
0.33 mg  kg 1
0.16 mg  kg 1
6.8 mg  kg 1

The potable water component values were derived using a drinking water Maximum Allowable Concentration of 0.00001 mg/L for
benzo(a)pyrene and the B[a]P PEFs listed in footnote b above, and the soil-to-groundwater model described in Appendix C of CCME (2006).
d
e
f

The SQGE is based on the lowest of the available environmental health guidelines (soil contact, soil and food ingestion, or protection of
freshwater life). For PAHs where a soil contact guideline was not available, an overall SQGE was not calculated.
This guideline is considered provisional because minimum data requirements, as outlined in CCME (2006), were not met. The value is presented
for users to consider applying at their own discretion, but it has not been used to determine the overall SQGE recommended here.
Modeling assumptions include the absence of biodegradation of PAHs in the subsurface environment, a highly conservative assumption.

14

 Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health
g
h

POLYCYCLIC AROMATIC
HYDROCARBONS

SQGFL for freshwater life protection back-calculated based on CCME (2006) protocol, using pre-existing CCME Water Quality Guidelines
(Freshwater Life) (CCME 1999).
SQGFL for freshwater life protection back-calculated from theoretically derived freshwater life thresholds based on baseline (narcosis-type)
toxicity along with a Critical Body Residue (CBR) approach, assuming an internalized dose for aquatic life of 3.0 mmol PAH·kg-1 lipid is a
threshold for chronic, non-lethal toxicity.

i

j

k

A freshwater life protective guideline could not be calculated based on the assumed generic site/soil properties and the KOC of the PAH, since the
concentration in groundwater at the point of leaching would need to far exceed the solubility limit to account for a concentration that approaches
the toxicity threshold at a point 10 m down-gradient.
The interim soil quality criterion (CCME 1991) is retained as the environmental soil quality guideline for this land use because there was
insufficient/inadequate data to calculate an SQGE or provisional SQGE. Consult the human health guidelines/check values to assess the human
hazard of PAH mixtures containing this PAH.
The SQGE is based on the soil contact guideline value. The 2008 benzo[a]pyrene SQGE replaces the 1997 provisional benzo[a]pyrene SQGE.
Consult the human health guidelines/check values to assess the human hazard of PAH mixtures containing this PAH.

l

Users may wish to consider the application, on a site-specific basis, of the Soil Quality Guideline for the Protection of Freshwater Life where
potential impacts on nearby surface water are a concern. This guideline value may be less than the common limit of detection in some
jurisdictions. Consult appropriate jurisdiction for further guidance.
m
Benzo[b]fluoranthene and benzo[j]fluoranthene tend to strongly co-elute under most gas chromatographic conditions. Furthermore, resolution
between benzo[b]fluoranthene, benzo[j]fluoranthene, and benzo[k]fluoranthene is difficult to achieve when all three isomers are present in the
soil matrix. Therefore, these three isomers have been considered together in deriving SQGHH values.
n
Data were insufficient/inadequate to update the 1997 provisional SQGE and no attempt was made to calculate a SQGHH or provisional SQGHH,
therefore the 1997 provisional SQGE is retained as the soil quality guideline for the protection of environmental health for this land use. However,
if there is concern for potential impacts to water bodies, the Soil Quality Guideline for the Protection of Freshwater Life (SQGFL) should be
applied. Consult other jurisdictions for the protection of human health from naphthalene.
o
Data were insufficient/inadequate data to calculate an SQGE or provisional SQGE and no attempt was made to calculate a SQGHH, or provisional
SQGHH,, therefore the interim soil quality criterion (CCME 1991) is retained as the environmental soil quality guideline for this land use.
However, if there is concern for potential impacts to water bodies, the Soil Quality Guideline for the Protection of Freshwater Life (SQGFL)
should be applied. Consult other jurisdictions for the protection of human health from phenanthrene.
p
The SQGE is based on the soil contact guideline value.
q
Data were insufficient/adequate data to calculate an SQGE or provisional SQGE and no attempt was made to calculate a SQGHH, or provisional
SQGHH, therefore the interim soil quality criterion (CCME 1991) is retained as the environmental soil quality guideline for this land use. Consult
other jurisdictions for the protection of human health from pyrene.
r
Resolution between benzo[b]fluoranthene and benzo[k]fluoranthene gas chromatograph peaks may be difficult to achieve. When these two PAHs
cannot be reported separately, report them as the sum of benzo[b+j+k]fluoranthene and compare this value to the guideline for
benzo[b]fluoranthene.

15

 POLYCYCLIC AROMATIC
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Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health

Figure 2. Example of how to apply Canadian Soil Quality Guidelines for PAHs at a contaminated site
PAH concentration in soil (mg/kg dry weight) collected from a contaminated industrial site (fictitious data).

Step 1

0.63
1.4
4.5
0.69
0.64
0.62

Benzo[g,h,i]perylene
0.67
Chrysene
1.6
Dibenz[a,h]anthracene
0.22
Indeno[1,2,3-c,d]pyrene
0.81
Naphthalene
0.66
(potentially carcinogenic PAHs are in bold)

PL
E

Acenaphthene
Anthracene
Benz[a]anthracene
Benzo[a]pyrene
Benzo[b]fluoranthene
Benzo[k]fluoranthene

To ensure that humans are protected from direct contact with soil contaminated with carcinogenic
PAHs, calculate the Benzo[a]pyrene Total Potency Equivalents (B[a]P TPE) using the following
Equation (see factsheet text and Table 1, footnote c, for more details);

B[a ]P T PE



n

 (C
i 1

i

 PEFi )

where,
B[a]P TPE = concentration of the carcinogenic-PAH mixture, expressed as a total potency equivalent of B[a]P
n
= number of carcinogenic PAHs (with an available PEF value)
Ci
= concentration of carcinogenic-PAH compound i
PEFi
= potency equivalence factor for the carcinogenic-PAH compound i (unitless) (see Table 1, footnote c)

AM

Take only the carcinogenic PAHs from the above table and calculate the B[a]P TPE as follows;

See Note 2 below for an explanation of this value

-1

-1

B[a]P TPE = (4.5 mg·kg × 0.1) + (0.69 mg·kg × 1) + (1.26 mg·kg-1 × 0.1) + (0.67 mg·kg-1 × 0.01) +
(1.6 mg·kg-1 × 0.01) + (0.22 mg·kg-1 × 1) + (0.81 mg·kg-1 × 0.1)
= 1.6 mg·kg-1
Compare the B[a]P TPE of 1.6 mg·kg-1 to the SQGDH in Table 1 with the desired level of acceptable risk. If the PAH
mixture is found in soil co-contaminated with coal tar or creosote, the B[a]P TPE should be multiplied by a safety
factor of 3 before comparison to the SQGDH, as follows; B[a]P TPE = 1.6 mg·kg-1 × 3 = 4.8 mg·kg-1

EX

Step 2

To ensure that potable water resources are protected from carcinogenic PAHs, calculate the Index of
Additive Cancer Risk (IACR) using the following equation (see factsheet text and Table 1, footnote
d, for more details);

IACR 

[ Benz ( a ) anthracene ] [ Benzo ( b  j  k ) fluoranthe ne ] [ Benzo ( g,h,i ) perylene ] [Benzo(a) pyrene] [Chrysene] [Dibenz(a,h)anthracene] [Indeno(1,2,3 c, d)pyrene]






2.7 mg  kg1
0.37 mg kg1
2.1mg kg1
0.23 mg kg1
0.33 mg  kg 1
0.16 mg  kg 1
6.8 mg  kg 1

Take only the carcinogenic PAHs from the above table and calculate the IACR as follows;
See Note 2 below for an explanation of this value

IACR = (4.5 mg·kg-1/0.33 mg·kg-1) + (1.26 mg·kg-1/0.16 mg·kg-1) + (0.67 mg·kg-1/6.8 mg·kg-1) +
(0.69 mg·kg-1/0.37 mg·kg-1) + (1.6 mg·kg-1/2.1 mg·kg-1) + (0.22 mg·kg-1/0.23 mg·kg-1) +
(0.81 mg·kg-1/2.7 mg·kg-1)
= 25
The resulting IACR value, in this case = 25, is equivalent to a hazard index and should not exceed a value of 1.0
(Table 1 shows that the SQGPW should be ≤ 1).

16

 Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health

POLYCYCLIC AROMATIC
HYDROCARBONS

PL
E

Note that for both the B[a]P TPE and IACR calculations;
1. no carcinogenic PAH should be left out of the calculations. If PAHs are suspected at a site, soil samples should be
analyzed for the full suite of carcinogenic PAHs. If analysis returns non-detects, and until further guidance, enter ½
the detection limit into the formulas. Consult the appropriate jurisdiction to confirm that this advice does not
conflict with program policy for dealing with non-detects at contaminated sites.
2. if concentrations of benzo[b]fluoranthene, benzo[j]fluoranthene, and benzo[k]fluoranthene are reported separately,
they should be summed together and expressed as a single value for benzo[b+j+k]fluoranthene. In this example,
benzo[b+j+k]fluoranthene = 0.64 mg·kg-1 + 0.62 mg·kg-1 = 1.26 mg·kg-1

Step 3

To protect environmental health from non-carcinogenic effects of PAHs (i.e. hazard assessed based on
non-carcinogenic modes of action), compare individual PAHs to the appropriate Soil Quality
Guideline (SQG) in the bottom half of Table 1.

At this point, the cancer hazard to humans from potentially carcinogenic PAHs has been assessed by calculating the
B[a]P TPE and IACR in Steps 1 and 2, respectively, above. Now the non-carcinogenic hazard of PAHs must be
assessed. Note that the non-carcinogenic hazard posed by PAHs to humans was not assessed; consult guidelines from
other jurisdictions for protection. Additionally, if a PAH displays both cancer and non-cancer effects to humans,
protect human health based on the threat from cancer.

AM

Take all PAH concentration data from the industrial site, and compare it to the appropriate environmental SQG from
Table 1(excerpt of which is provided
below);

Results of comparison between PAHs at industrial site and available SQGs to protect environmental health;
: There is no SQG for the protection of environmental health reported in Table 1 for this
PAH. However, Table 2 provides value(s) for individual environmental soil pathway(s)
that could be developed. Consult guidelines from other jurisdictions for the protection of
humans from non-carcinogenic effects of this PAH. This conclusion would also apply to
acenaphthylene and fluorene if it were present at the site.
: The value indicated by the arrow is valid for the protection environmental health from
non-carcinogenic effects of this PAH. Consult guidelines from other jurisdictions for the
protection of humans from non-carcinogenic effects of this PAH.
: The value indicated by the arrow is valid for the protection of environmental health from
non-carcinogenic effects of this PAH. For human health, the hazard posed by this PAH is
assessed solely based on its carcinogenic potential (see Steps 1 and 2).
: Same conclusion as for benz[a]anthracene.
: Same conclusion as for benz[a]anthracene. Additionally, if benzo[b]fluoranthene and
benzo[k]fluoranthene cannot be reported separately, report them as the sum of
benzo[b+j+k]fluoranthene and compare this value to the guideline for the combined 3
isomers reported in Table 1.

EX

Acenaphthene

Anthracene

Benz[a]anthracene

Benzo[a]pyrene
Benzo[b]fluoranthene

17

 POLYCYCLIC AROMATIC
HYDROCARBONS

Chrysene

EX

AM

Dibenz[a,h]anthracene
Indeno[1,2,3-c,d]pyrene
Naphthalene

: Same conclusion as for benzo[b]fluoranthene.
: There is no SQG reported for the protection of environmental health (Table 1), or
individual environmental soil pathways (Table 2) for this PAH. For human health, the
hazard posed by this PAH is assessed solely based on its carcinogenic potential (see Steps
1 and 2).
: There is no SQG for the protection of environmental health reported in Table 1 for this
PAH. However, Table 2 provides value(s) for individual environmental soil pathway(s)
that could be developed. For human health, the hazard posed by this PAH is assessed
solely based on its carcinogenic potential (see Steps 1 and 2).
: Same conclusion as for benz[a]anthracene.
: Same conclusion as for benz[a]anthracene.
: The value indicated by the arrow is valid for the protection of environmental health from
non-carcinogenic effects of this PAH. Consult guidelines from other jurisdictions for the
protection of humans from non-carcinogenic effects of this PAH.

PL
E

Benzo[k]fluoranthene
Benzo[g,h,i]perylene

Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health

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 Canadian Soil Quality Guidelines for the
Protection of Environmental and Human Health

POLYCYCLIC AROMATIC
HYDROCARBONS

Reference listing:
Canadian Council of Ministers of the Environment. 2010. Canadian soil quality guidelines for the protection of
environmental and human health: Carcinogenic and Other PAHs. In: Canadian environmental quality guidelines, 1999,
Canadian Council of Ministers of the Environment, Winnipeg.
For further scientific information, contact:

For additional copies, contact:

Environment Canada
National Guidelines and Standards Office
200 Sacré-Coeur Blvd.
Gatineau, QC K1A 0H3
Phone: (819) 953-1550
E-mail: ceqg-rcqe@ec.gc.ca
Internet: http://www.ec.gc.ca/ceqg-rcqe

CCME Documents
Toll-Free Phone: (800) 805-3025
Internet: http://www.ccme.ca

© Canadian Council of Ministers of the Environment 2010
Excerpt from Publication No. 1299; ISBN 1-896997-34-1

Aussi disponible en français.

19