Polycyclic aromatic hydrocarbons (PAHs) in people living in Canada

Learn about human biomonitoring of polycyclic aromatic hydrocarbons (PAHs) in Canada.

On this page

• About polycyclic aromatic hydrocarbons (PAHs)
• Data sources for polycyclic aromatic hydrocarbon (PAH) biomonitoring
• Results of polycyclic aromatic hydrocarbon (PAH) biomonitoring
• Related links
• How to cite this web page

About polycyclic aromatic hydrocarbons (PAHs)

Polycyclic aromatic hydrocarbons (PAHs) are a large group of compounds that have 2 or more fused (joined together) aromatic rings made up of carbon and hydrogen.

PAHs are released to the environment from both natural and human-made sources, although the contribution from human-made sources is much higher.

The main sources of human-made PAH emissions are:

• industrial activity
• residential wood burning

PAHs can also be formed or released to the environment from:

• cooking
• tobacco or cannabis smoke
• vehicle exhaust
• waste incineration
• tar, asphalt and creosote-treated products
• building products such as paints, stains and carpeting
• oil spills

Forest fires are the largest natural source of PAH emissions in Canada.

People are exposed to PAHs by:

• breathing air, eating foods (including human milk), drinking water, or swallowing dust contaminated with PAHs
  • levels in foods depend on the source of the food and the method of cooking
• smoking cigarettes or cannabis
• skin contact with soot and tars

People are generally exposed to mixtures of PAHs. PAHs commonly detected in people living in Canada include:

• fluorene
• naphthalene
• phenanthrene
• pyrene

PAHs are absorbed in the body and undergo metabolism. During metabolism, oxygen and hydrogen are added to the PAH to form a hydroxylated PAH metabolite. These metabolites are measured in a urine sample. The presence of hydroxylated PAHs in your urine reflects recent exposure to PAHs.

Potential health effects of PAHs

The International Agency for Research on Cancer has classified PAH-containing mixtures such as soot and coal tar as carcinogenic (causing cancer) to humans.

The likelihood that a PAH causes cancer varies based on the type of PAH you are exposed to and how you are exposed to it. Classifications for individual PAHs range from carcinogenic to not currently classifiable based upon available information. Naphthalene is classified as possibly carcinogenic to humans. Fluorene, phenanthrene and pyrene aren't currently classifiable based on the strength of evidence for cancer.

It's important to note that the presence of a substance in your body doesn't necessarily mean it will affect your health.

What we're doing to lower human exposures to PAHs

We have:

• identified PAHs as toxic under the Canadian Environmental Protection Act, 1999
• developed risk management tools to reduce the emissions of PAHs from certain industrial facilities
• established a guideline for naphthalene in residential indoor air
• established guidelines for various PAHs in water and in soil
• added certain PAHs and their metabolites, including naphthalene, to the list of ingredients that are restricted or prohibited for use in cosmetic products

We continue to monitor and assess PAHs.

Data sources for polycyclic aromatic hydrocarbon (PAH) biomonitoring

This fact sheet presents human biomonitoring data for 4 common PAHs from the:

• Canadian Health Measures Survey (CHMS)
• Contaminant Biomonitoring in the Northwest Territories Mackenzie Valley
• Qanuilirpitaa? 2017 Nunavik Inuit Health Survey (Q2017)

You can access more results for PAHs in the Canadian population through the Canadian biomonitoring dashboard.

We wish to acknowledge all participants, including Indigenous peoples, who took part in the biomonitoring studies.

Results of polycyclic aromatic hydrocarbon (PAH) biomonitoring

Figure 1: Levels in the Canadian population, by smoking status

Average levels of fluorene, naphthalene, phenanthrene and pyrene were higher in people who smoke cigarettes than in people who don't smoke cigarettes. From 2009 to 2015, average levels of fluorene, naphthalene, phenanthrene and pyrene were relatively unchanged in both groups.

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Table 1, Levels in Canadian population, by smoking status

Chemical	Collection period	Smoking status	Geometric mean level (µg/L)	95% confidence interval (µg/L)
Fluorene	2009 to 2011	People who don't smoke	0.42	0.38–0.46
Fluorene	2009 to 2011	People who smoke	2.1	1.8–2.5
Fluorene	2012 to 2013	People who don't smoke	0.39	0.34–0.43
Fluorene	2012 to 2013	People who smoke	2.3	1.9–2.8
Fluorene	2014 to 2015	People who don't smoke	0.43	0.38–0.47
Fluorene	2014 to 2015	People who smoke	2.1	1.7–2.6
Naphthalene	2009 to 2011	People who don't smoke	4.6	4.0–5.3
Naphthalene	2009 to 2011	People who smoke	19	16–23
Naphthalene	2012 to 2013	People who don't smoke	4.4	3.9–4.9
Naphthalene	2012 to 2013	People who smoke	17	14–21
Naphthalene	2014 to 2015	People who don't smoke	5.0	4.6–5.4
Naphthalene	2014 to 2015	People who smoke	16	13–20
Phenanthrene	2009 to 2011	People who don't smoke	0.34	0.31–0.36
Phenanthrene	2009 to 2011	People who smoke	0.80	0.66–0.96
Phenanthrene	2012 to 2013	People who don't smoke	0.30	0.26–0.35
Phenanthrene	2012 to 2013	People who smoke	0.77	0.64–0.94
Phenanthrene	2014 to 2015	People who don't smoke	0.34	0.31–0.37
Phenanthrene	2014 to 2015	People who smoke	0.75	0.61–0.93
Pyrene	2009 to 2011	People who don't smoke	0.091	0.084–0.099
Pyrene	2009 to 2011	People who smoke	0.23	0.18–0.28
Pyrene	2012 to 2013	People who don't smoke	0.072	0.062–0.085
Pyrene	2012 to 2013	People who smoke	0.19	0.16–0.23
Pyrene	2014 to 2015	People who don't smoke	0.082	0.072–0.093
Pyrene	2014 to 2015	People who smoke	0.19	0.15–0.23

Figure 2: Levels in the Canadian population, by age group (in people who don't smoke cigarettes)

Average levels of fluorene, naphthalene and phenanthrene were generally similar across age groups in people who don't smoke cigarettes. Average levels of pyrene were higher in adolescents and people aged 20 to 39 than in older adults.

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Table 2, Levels in Canadian population, non-smokers by age group

Chemical	Collection period	Age group (years)	Geometric mean level (µg/L)	95% confidence interval (µg/L)
Fluorene	2009 to 2011	12 to 19	0.49	0.44–0.54
Fluorene	2009 to 2011	20 to 39	0.47	0.39–0.56
Fluorene	2009 to 2011	40 to 59	0.40	0.33–0.48
Fluorene	2009 to 2011	60 to 79	0.37	0.32–0.42
Fluorene	2012 to 2013	12 to 19	0.45	0.37–0.53
Fluorene	2012 to 2013	20 to 39	0.51	0.43–0.61
Fluorene	2012 to 2013	40 to 59	0.35	0.30–0.41
Fluorene	2012 to 2013	60 to 79	0.32	0.26–0.40
Fluorene	2014 to 2015	12 to 19	0.46	0.40–0.52
Fluorene	2014 to 2015	20 to 39	0.49	0.42–0.56
Fluorene	2014 to 2015	40 to 59	0.42	0.34–0.53
Fluorene	2014 to 2015	60 to 79	0.38	0.33–0.44
Naphthalene	2009 to 2011	12 to 19	5.6	4.9–6.4
Naphthalene	2009 to 2011	20 to 39	5.1	3.8–6.8
Naphthalene	2009 to 2011	40 to 59	4.2	3.0–5.8
Naphthalene	2009 to 2011	60 to 79	4.0	3.2–4.9
Naphthalene	2012 to 2013	12 to 19	6.1	4.9–7.5
Naphthalene	2012 to 2013	20 to 39	5.6	4.7–6.7
Naphthalene	2012 to 2013	40 to 59	4.0	3.2–5.0
Naphthalene	2012 to 2013	60 to 79	3.3	2.8–4.1
Naphthalene	2014 to 2015	12 to 19	5.8	5.1–6.5
Naphthalene	2014 to 2015	20 to 39	5.7	4.6–7.0
Naphthalene	2014 to 2015	40 to 59	5.0	4.2–6.0
Naphthalene	2014 to 2015	60 to 79	4.1	3.2–5.2
Phenanthrene	2009 to 2011	12 to 19	0.36	0.32–0.41
Phenanthrene	2009 to 2011	20 to 39	0.36	0.30–0.43
Phenanthrene	2009 to 2011	40 to 59	0.33	0.28–0.40
Phenanthrene	2009 to 2011	60 to 79	0.32	0.28–0.38
Phenanthrene	2012 to 2013	12 to 19	0.32	0.27–0.38
Phenanthrene	2012 to 2013	20 to 39	0.39	0.32–0.46
Phenanthrene	2012 to 2013	40 to 59	0.29	0.23–0.36
Phenanthrene	2012 to 2013	60 to 79	0.27	0.22–0.34
Phenanthrene	2014 to 2015	12 to 19	0.35	0.31–0.40
Phenanthrene	2014 to 2015	20 to 39	0.36	0.32–0.40
Phenanthrene	2014 to 2015	40 to 59	0.32	0.27–0.39
Phenanthrene	2014 to 2015	60 to 79	0.36	0.30–0.42
Pyrene	2009 to 2011	12 to 19	0.15	0.13–0.17
Pyrene	2009 to 2011	20 to 39	0.11	0.090–0.13
Pyrene	2009 to 2011	40 to 59	0.074	0.060–0.091
Pyrene	2009 to 2011	60 to 79	0.056	0.048–0.065
Pyrene	2012 to 2013	12 to 19	0.10	0.088–0.12
Pyrene	2012 to 2013	20 to 39	0.10	0.077–0.13
Pyrene	2012 to 2013	40 to 59	0.061	0.053–0.070
Pyrene	2012 to 2013	60 to 79	0.052	0.039–0.069
Pyrene	2014 to 2015	12 to 19	0.10	0.084–0.12
Pyrene	2014 to 2015	20 to 39	0.098	0.084–0.11
Pyrene	2014 to 2015	40 to 59	0.074	0.060–0.091
Pyrene	2014 to 2015	60 to 79	0.060	0.050–0.072

Figure 3: Levels in the Canadian population, by sex (in people who don't smoke cigarettes)

Average levels of fluorene, naphthalene, phenanthrene and pyrene were similar between sexes in people who don't smoke cigarettes.

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Table 3, Levels in Indigenous Peoples living in the Northwest Territories, non-smokers by sex

Chemical	Collection period	Sex	Geometric mean level (µg/L)	95% confidence interval (µg/L)
Fluorene	2009 to 2011	Females	0.38	0.34–0.43
Fluorene	2009 to 2011	Males	0.47	0.42–0.52
Fluorene	2012 to 2013	Females	0.35	0.29–0.40
Fluorene	2012 to 2013	Males	0.44	0.39–0.48
Fluorene	2014 to 2015	Females	0.39	0.34–0.45
Fluorene	2014 to 2015	Males	0.46	0.40–0.54
Naphthalene	2009 to 2011	Females	4.7	3.9–5.6
Naphthalene	2009 to 2011	Males	4.5	3.9–5.3
Naphthalene	2012 to 2013	Females	4.0	3.3–5.0
Naphthalene	2012 to 2013	Males	4.8	4.1–5.5
Naphthalene	2014 to 2015	Females	5.1	4.3–6.0
Naphthalene	2014 to 2015	Males	4.9	4.5–5.4
Phenanthrene	2009 to 2011	Females	0.32	0.28–0.36
Phenanthrene	2009 to 2011	Males	0.36	0.32–0.40
Phenanthrene	2012 to 2013	Females	0.28	0.23–0.33
Phenanthrene	2012 to 2013	Males	0.33	0.29–0.38
Phenanthrene	2014 to 2015	Females	0.32	0.29–0.36
Phenanthrene	2014 to 2015	Males	0.36	0.32–0.40
Pyrene	2009 to 2011	Females	0.084	0.076–0.093
Pyrene	2009 to 2011	Males	0.099	0.088–0.11
Pyrene	2012 to 2013	Females	0.065	0.055–0.078
Pyrene	2012 to 2013	Males	0.082	0.068–0.099
Pyrene	2014 to 2015	Females	0.074	0.065–0.085
Pyrene	2014 to 2015	Males	0.091	0.076–0.11

Figure 4: Levels in First Nations and Métis living in the Northwest Territories

Average levels of fluorene, naphthalene, phenanthrene and pyrene in First Nations and Métis from the Mackenzie Valley in the Northwest Territories (NWT) were similar to average levels in the general population in the CHMS.

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Table 4, Levels in Inuit living in Nunavik

Chemical	Collection period	Biomonitoring initiative	Geometric mean level (µg/L)	95% confidence interval (µg/L)
Fluorene	2014 to 2015	CHMS	0.58	0.52–0.65
Fluorene	2016 to 2017	NWT	0.73	0.58–0.91
Naphthalene	2014 to 2015	CHMS	6.2	5.6–6.9
Naphthalene	2016 to 2017	NWT	7.6	6.2–9.3
Phenanthrene	2014 to 2015	CHMS	0.41	0.36–0.45
Phenanthrene	2016 to 2017	NWT	0.30	0.25–0.37
Pyrene	2014 to 2015	CHMS	0.096	0.087–0.11
Pyrene	2016 to 2017	NWT	0.090	0.070–0.11

Figure 5: Levels in Inuit living in Nunavik

Average levels of fluorene and pyrene among Inuit from the Q2017 survey in Nunavik were higher than in the general population in the CHMS. Average levels of naphthalene and phenanthrene among Inuit were similar to the general population in the CHMS.

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Table 5, Levels in the Northwest Territories

Chemical	Collection period	Biomonitoring initiative	Arithmetic mean level (µg/L)	95% confidence interval (µg/L)
Fluorene	2014 to 2015	CHMS	1.2	0.99–1.4
Fluorene	2017	Q2017	2.5	2.3–2.8
Naphthalene	2014 to 2015	CHMS	23	8.2–38
Naphthalene	2017	Q2017	24	22–27
Phenanthrene	2014 to 2015	CHMS	0.64	0.57–0.71
Phenanthrene	2017	Q2017	0.76	0.69–0.82
Pyrene	2014 to 2015	CHMS	0.16	0.14–0.18
Pyrene	2017	Q2017	0.23	0.21–0.25

Related links

• Canadian biomonitoring dashboard
• Toxic substances list: polycyclic aromatic hydrocarbons (PAHs)
• Naphthalene
• Polycyclic aromatic hydrocarbons (PAHs) levels in urine samples collected in a subarctic region of the Northwest Territories, Canada
• Exposure to benzene, toluene and polycyclic aromatic hydrocarbons in Nunavimmiut aged 16 years and over (Nunavik, Canada) - Qanuilirpitaa 2017 survey
• Chemical Agents and Related Occupations: IARC Monographs on the Evaluation of Carcinogenic Risks to Humans
• Some Non-heterocyclic Polycyclic Aromatic Hydrocarbons and Some Related Exposures: IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Volume

How to cite this web page

Health Canada. 2024. PAHs in people living in Canada. Ottawa, ON. Available: https://www.canada.ca/en/health-canada/services/environmental-workplace-health/reports-publications/environmental-contaminants/human-biomonitoring-resources/polycyclic-aromatic-hydrocarbons-in-people.html