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Exposure Reduction

Our team has performed a detailed scan of exposure control resources and assembled a compilation of key publications and resources. These are organized by type of exposure (environmental or occupational) and by specificity (general or carcinogen-specific). Please visit our Exposure Reduction Resources page to view.

We also recommend exploring the Prevention Policies Directory, a freely-accessible online tool offering information on policies related to cancer and chronic disease prevention. Providing summaries of the policies and direct access to the policy documents, the Directory allows users to search by carcinogen, risk factor, jurisdiction, geographical location, and document type. The Canadian Partnership Against Cancer has also developed an ultraviolet radiation policy pack to support evidence-informed actions for local and provincial/territorial governments. For questions about these resources, please contact a member of the Prevention Team at the Canadian Partnership Against Cancer at [email protected].

Subscribe to our newsletters

The CAREX Canada team offers two regular newsletters: the biannual e-Bulletin summarizing information on upcoming webinars, new publications, and updates to estimates and tools; and the monthly Carcinogens in the News, a digest of media articles, government reports, and academic literature related to the carcinogens we’ve classified as important for surveillance in Canada. Sign up for one or both of these newsletters below.

CAREX Canada

School of Population and Public Health

University of British Columbia
Vancouver Campus
370A - 2206 East Mall
Vancouver, BC  V6T 1Z3
CANADA

© 2025 CAREX Canada
Simon Fraser University

As a national organization, our work extends across borders into many Indigenous lands throughout Canada. We gratefully acknowledge that our host institution, the University of British Columbia Point Grey campus, is located on the traditional, ancestral, and unceded territories of the xʷməθkʷəy̓əm (Musqueam) people.

Asbestos

Asbestos

Asbestos Profile

FIBERS AND DUSTS  KNOWN CARCINOGEN (IARC 1)

CAS No. 1332-21-4
IARC Monograph Vol. 14, Suppl. 7, 1987 (Group 1)
IARC Monograph Vol. 100C, 2012 (Group 1)

Asbestos Profile

QUICK SUMMARY

  • A group of naturally occurring, fibrous silicate minerals
  • Associated cancers: Mesothelioma, lung and ovarian cancer
  • Most important route of exposure: Inhalation
  • Uses: Found in roofing, thermal and electrical insulation, cement pipe and sheets, friction materials (such as automobile brakes), and other products
  • Occupational exposures: Approx. 235,000 Canadians are exposed at work, mostly in the construction sector
  • Environmental exposures: Via buildings that have deteriorating asbestos insulation or have undergone poorly performed asbestos removal
  • Fast fact: The Government of Canada banned asbestos and asbestos-containing products in 2018, with a few exceptions.

General Information

Asbestos is the general term for a group of naturally occurring, fibrous silicate minerals.[1] The most abundant form is chrysotile, which is found in bundles of fibres that can exceed 10 cm in length. Chrysotile is the only serpentine variety. The five amphibole varieties include amosite, crocidolite, actinolite, tremolite, and anthophyllite. Asbestos has been widely used in commercial applications because of its heat resistance, tensile strength, insulating and friction characteristics, as well as its ability to be woven.[1]

Asbestos is released into the environment by natural and anthropogenic sources.[2] The ability of asbestos fibres to enter and deposit in the lungs depends on their length, diameter, and chemical composition. These factors also influence the body’s ability to clear the fibres. Thin fibers (≥8 μm long with a diameter ≤1.5 μm) have the greatest potential to enter the lungs and are the most potent carcinogens.[1]

Asbestos has been classified by IARC as Group 1, carcinogenic to humans, with well established links to pleural and peritoneal mesotheliomas, and to lung cancer. IARC’s review of Group 1 carcinogens in 2012 reaffirmed this classification, and also found “sufficient evidence in humans” for ovarian cancer, and “limited evidence in humans” for colorectal, pharynx, and stomach cancers.[3] People who smoke and are exposed to asbestos have an even higher risk of lung cancer.[1] Research also reports increases in laryngeal and some other cancers with this combination of exposures, although the strength of association varies.[4]

Asbestosis, a serious disease characterized by scar tissue in the lungs and in the pleural membrane, is caused by exposure to high concentrations of asbestos. Symptoms include difficulty breathing, coughing, and in severe cases heart enlargement, disability, and death.[2]

Regulations and Guidelines

In 2018, the Prohibition of Asbestos and Products Containing Asbestos Regulations came into force.[5] This regulation prohibits the import, sale and use of asbestos, as well as the manufacture, import, sale and use of products containing asbestos. The regulations do not apply to mining residues, except for in high risk activities. A number of exemptions were made, including, but not limited to, the import, sale, or use of products containing asbestos to service equipment in nuclear facilities until 2022 and the import and use of asbestos for chlor-alkali facilities until 2029.

Occupational exposure limits (OEL) [6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]

Canadian JurisdictionsAsbestos FormOEL (f/cc)
Canada Labour Codeall0.1 [f]
ABall0.1
BC, MB, ON, NL, NS, PEall0.1 [f]
NBamosite, tremolite
chrysotile
crocidolite
0.5 [f]
2 [f]
0.2 [f]
QCactinolite, anthophyllite,chrysotile, tremolite
amosite, crocidolite
1 [f,em]; 5 [stel]
0.2 [f,em]; 1 [stel]
NT, NU, SKallNo limit listed, special instructions
for high-risk activities
YTamosite
crocidolite
chrysotile, tremolite
0.2; 2 [stel]
0.1
0.5; 5 [stel]
Other JurisdictionAsbestos FormOEL (f/cc)
ACGIH 2020 TLVall0.1 [f]
f/cc = fibers per cubic centimeter
f = fibres longer than 5 microns, with an aspect ratio of equal than/greater than 3:1
em = exposure must be reduced to the minimum
stel = short term exposure limit (15 min. maximum)
ACGIH = American Conference of Governmental Industrial Hygienists
TLV = threshold limit value

 

Canadian environmental guidelines and standards*

JurisdictionLimitYear
Ontario Ambient Air Quality Criteria24-hour: 0.04 fibres/cm3, for asbestos fibers greater than 5 µg in length2016[21]
Quebec’s Clean Air RegulationProhibited discharge of asbestos into the air if the concentration of exceeds the standard of 2 fibres per cm3 of dry gas at reference conditions, caused by drilling, crushing, drying, dry rock storage, ore processing or asbestos processing in a mine or asbestos extraction plant2011[22]
British Columbia’s Contaminated Sites Regulation, BC Reg 375/96

Sets soil standards for the protection of human health: 1% by weight (10,000 μg/g)

Drinking water: 7 m.f./L

2019[23]
*Standards are legislated and legally enforceable, while guidelines (including Ontario ambient air quality criteria) describe concentrations of contaminants in the environment (e.g. air, water) that are protective against adverse health, environmental, or aesthetic (e.g. odour) effects
m.f./L = million fibres > 10 µm/L

Canadian agencies/organizations

AgencyDesignation/PositionYear
Health CanadaDSL – low priority substance (already risk managed)2006[24]
CEPASchedule 1, paragraph ‘c’ (human health)1999[25]
Environment Canada’s National Pollutant Release InventoryReportable to NPRI if manufactured, processed, or otherwise used at quantities greater than 10 tonnes2017[26]
DSL = domestic substance list
CEPA = Canadian Environmental Protection Act

Asbestos was not included in other Canadian government guidelines, standards, or chemical listings reviewed.

International agencies/organizations

AgencyDesignation/PositionYear
International Labour Organization (ILO)Prohibition on spraying all forms of
asbestos and on using crocidolite and
crocidolite-containing products
1986[27]
European UnionBan on the use of all forms of asbestos2003[28,29]

Main Uses

Chrysotile has always been the most important asbestos fibre used commercially. Amosite, crocidolite, and actinolite were also used in commercial products, while tremolite and anthophyllite were typically encountered as contaminants.[1]

Asbestos was used primarily for roofing, thermal and electrical insulation, cement pipe and sheets, flooring, gaskets, friction materials, coatings, plastics, textiles, paper, and other products.[1]

Asbestos use peaked in the late 1960s and early 1970s, when there were more than 3,000 industrial applications or asbestos-containing products.[1] When asbestos use hit its peak in 1973, US consumption totaled 801,000 tonnes (t) and the major markets in the US included asbestos-cement pipes (192,000 t); flooring (176,000 t); roofing (72,000 t); friction products, such as automobile brakes and clutches (64,000 t); and packing and gaskets (24,000 t).[30]

Consumption of unmanufactured asbestos fiber in the United States was 343 t in 2015, down by 16% from 406 t in 2014. The chloralkali industry, which uses asbestos to manufacture semi-permeable diaphragms accounted for an estimated 95% of domestic asbestos consumption during 2015.[31]

Canadian Production and Trade

Prior to the closure of two Canadian asbestos mines in 2011,[32] Canada was a major producer and exporter of asbestos. Approximately 410,000 tonnes of asbestos was produced in Canada between 2008 and 2010, accounting for roughly 6% of total global production in the same period.[33] Following the ban on asbestos in 2018, trade has decreased drastically. However, trade data from 2020 show that Canada does still import asbestos, including friction materials, tubes and pipes, and corrugated sheets and panels,[34] likely due to exemptions outlined in the regulation.[5]

Production and trade

ActivityQuantityYear
Import:1 t of ‘asbestos’2020[35]
Export:0 t of ‘asbestos’2020[35]
t = tonne

Environmental Exposures Overview

In the environment, the primary route of exposure is by inhaling air contaminated with asbestos. People may be exposed to higher-than-average levels of asbestos in air if they use asbestos-containing products, or live or work in buildings with deteriorating asbestos insulation or that have undergone poorly performed asbestos removal.[2] People may also be exposed during home renovations if asbestos containing materials are disturbed. Asbestos was used in over 3,000 different building materials used from the 1950s to 1990s such as stucco, flooring, roof shingles, and insulation.[36,37] Family members of asbestos workers may also be exposed through contaminated work clothing.[38] CAREX Canada estimates that asbestos levels in indoor and outdoor air may result in increased risks of cancer at a population level (very low data quality).

Vermiculite insulation produced between the 1920s and 1990s and used in homes may contain amphibole asbestos and could be an exposure hazard if disturbed.[39] Vermiculite products marketed for garden use may also contain asbestos. An EPA study in the Seattle area in 2000 found 5 of 16 purchased products were contaminated with asbestos.[40]

Although contaminated air is the most important route of exposure in the general population, people may also be exposed by ingesting drinking water in areas where asbestos occurs (either naturally or from human activities). There is a great deal of debate on the carcinogenic role (if any) of exposure to asbestos via drinking water. In general, there is no consistent evidence to support this hypothesis.[1,41] CAREX Canada estimates that exposure to asbestos via drinking water or food and beverages is negligible.

Asbestos is geologically related to talc, a substance that may be used in cosmetics and pharmaceuticals, and as a food additive. Talc from some mine deposits can be contaminated with asbestos, especially anthophyllite and tremolite.[1] When used as a food additive, talc must be asbestos free, as per the Food and Drug Regulations.[42] The Prohibition of Asbestos and Products Containing Asbestos Regulations prohibits asbestos above trace levels in consumer products, including cosmetics.[43] However, the responsibility of testing lies with the manufacturers.

Searches of Environment Canada’s National Pollutant Release Inventory (NPRI) and the US Consumer Product Information Database yielded the following results on current potential for exposure to asbestos in Canada:

NPRI and US Consumer Product Information Database

NPRI 2017[44]
Substance name: ‘Asbestos (friable form)’
CategoryQuantityIndustry
Released into EnvironmentNoneWaste treatment and disposal,
Remediation and waste management,
petroleum and coal product manufacturing
pesticide, fertilizer and other agricultural
chemical manufacturing,
oil and gas extraction
(50 facilities)
Disposed of24,126 t
Sent to off-site recycling28 t
US Consumer Products 2018[45]
Search TermQuantityProduct Type
‘chrysotile asbestos’5Roofing sealant cements
‘anthophyllite asbestos’4Paint primer
t = tonne

For more information, see the environmental exposure estimate for asbestos.

Occupational Exposures Overview

Inhalation is the most important route of occupational exposure to asbestos.[1]

Current asbestos-related disease is associated with exposures that occurred 10 to 40 years ago. This is due to the latency period between exposure and onset of disease. Exposure sources at that time included manufactured products and buildings containing asbestos, as well as the act of mining and milling asbestos. Exposure today tends to involve contact with older asbestos-containing products, which is referred to as secondary exposure.

CAREX Canada estimates that approximately 235,000 Canadians are exposed to asbestos in the workplace. The largest industrial groups exposed are specialty trade contractors, followed by building construction, public administration, schools, and hospitals. By occupation, the largest exposed groups are carpenters, construction trades helpers and labourers, electricians, and janitors, caretakers and building superintendents.

Exposure in construction workers is difficult to monitor due to the wide variety of worksites and the transient nature of employment for many workers. Despite this, the INSPQ in Quebec released a report on exposures to asbestos in the construction industry.[46]

According to the Burden of Occupational Cancer in Canada project, occupational exposure to asbestos leads to approximately 1,900 lung cancers and 430 mesotheliomas each year, based on past exposures (1961-2001).[47,48] This amounts to 8% of all lung cancers and 81% of all mesotheliomas diagnosed annually (almost all of the remaining mesotheliomas are likely due to environmental asbestos exposure). Most asbestos-related cancers occur among workers in the manufacturing and construction sectors. Work-related asbestos exposure resulted in approximately $2.35 billion in costs for newly diagnosed lung cancer and mesothelioma cases in 2011.[49]

For detailed estimates of exposure to asbestos, see the occupational exposures tab.

Sources

1. National Toxicology Program (NTP). 14th Report on Carcinogens for Asbestos (2016) (PDF)
2. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Asbestos, US Dept. of Health & Human Services (2001) (PDF)
3. The Globe and Mail. Canadian asbestos production suspended (2011)
4. International Agency for Research on Cancer (IARC). Monograph summary, Volume 14, Supplement 7 (1987) (PDF)
9. The Canadian Legal Information Institute (CanLII) Manitoba Regulation 217/2006 Workplace Safety and Health Regulation (2022)
11. Government of Newfoundland and Labrador. Regulation 5,12 Occupational Health and Safety Regulations (2018)
12. Government of the Northwest Territories. Occupational Health and Safety Regulations, R-039-2015 (2020) (PDF)
14. The Canadian Legal Information Institute (CanLII). Government of Nunavut’s Occupational Health and Safety Regulations, Nu Reg 003-2016 (2010)
16. Government of Prince Edward Island. Occupational Health and Safety Act Regulations Chapter 0-1 (2013) (PDF)
18. The Canadian Legal Information Institute (CanLII) The Occupational Health and Safety Regulations, 1996 (2022)
19. The Canadian Legal Information Institute (CanLII). Yukon’s Occupational Health Regulations, O.I.C. 1986/164 (2020) (PDF)
20. Occupational Safety and Health Administration (OSHA). Annotated PELs (2020)
21. Ontario Ministry of the Environment and Climate Change. Ontario’s Ambient Air Quality Criteria (2019)
22. Government of Quebec. Clean Air Regulation, Q-2, r. 4.1 (2020)
23. Government of British Columbia. Contaminated Sites Regulation B.C. Reg. 375/96 (2021)
24. Health Canada. Prioritization of the DSL (2006)
25. Environment and Climate Change Canada. CEPA List of Toxic Substances (2020)
27. International Labour Organization (ILO). Convention No. 162 Concerning Safety in the Use of Asbestos
30. US Geological Survey. Minerals Year Book, Asbestos (2000) (PDF)
31. US Geological Survey. Minerals Year Book, Asbestos (2015) (PDF)
32. US Geological Survey. Minerals Year Book, Asbestos [Advance Release] (2012) (PDF)
33. Natural Resources Canada. Mineral and Metals Sector. Commodity reviews – 2011
34. Innovation, Science and Economic Development Canada. Trade Data Online (2021) (Search term: asbestos)
35. International Trade Centre. TradeMap (Free subscription required)
36. WorkSafeBC. Asbestos
38. Donovan EP, Donovan BL, McKinley MA, Cowan DM, Paustenback DJ.“Evaluation of take home (para-occupational) exposure to asbestos and disease: a review of the literature.” Crit Rev Toxicol 2012;42(9):703-730.
41. World Health Organization (WHO). Asbestos in Drinking Water (2021) (PDF)
42. Environment and Climate Change Canada and Health Canada . Draft screening assessment talc (Mg3H2(SiO3)4) (2018)
44. Environment and Climate Change Canada. National Pollutant Release Inventory (NPRI) Inventory data search (Substance name: ‘(1332-21-4) Asbestos (friable form only)’)
45. Consumer Product Information Database (CPID).What’s in it? (2022) (Search term: ‘Asbestos’)
47. Labrèche F, Kim J, Song C, Pahwa M, Calvin BG, Arrandale VH, McLeod CB, Peters CE, Lavoué J, Davies HW, Nicol AM. “The current burden of cancer attributable to occupational exposures in Canada.” Prev Med 2019;122:128-39.
48. Occupational Cancer Research Centre. Burden of Occupational Cancer (2017)
49. Tompa E, Kalcevich C, McLeod C, Lebeau M, Song C, McLeod K, Kim J, Demers PA. “The Economic Burden of Lung Cancer and Mesothelioma Due to Occupational and Para-Occupational Asbestos Exposure.” Occup Environ Med 2017;74(11):816-822.

   

Other Resources

  1. Institut National de Sante Publique du Quebec. The Epidemiology of Asbestos Related disease in Quebec. (2004).
  2. Marrett LD, Ellison LF, Dryer D. “Canadian cancer statistics at a glance: mesothelioma.” Canadian Medical Association Journal2008;178(6):677-8.
  3. Service Canada. Asbestos Service Canada Centre
  4. Canada Mortgage and Housing Corporation. Asbestos
  5. Mining Watch Canada. Asbestos (PDF)
  6. Agency for Toxic Substances and Disease Registry (ATSDR). ToxFAQ Sheet for Asbestos (2001) (PDF)

Subscribe to our newsletters

The CAREX Canada team offers two regular newsletters: the biannual e-Bulletin summarizing information on upcoming webinars, new publications, and updates to estimates and tools; and the monthly Carcinogens in the News, a digest of media articles, government reports, and academic literature related to the carcinogens we’ve classified as important for surveillance in Canada. Sign up for one or both of these newsletters below.

CAREX Canada

School of Population and Public Health

University of British Columbia
Vancouver Campus
370A - 2206 East Mall
Vancouver, BC  V6T 1Z3
CANADA

© 2025 CAREX Canada
Simon Fraser University

As a national organization, our work extends across borders into many Indigenous lands throughout Canada. We gratefully acknowledge that our host institution, the University of British Columbia Point Grey campus, is located on the traditional, ancestral, and unceded territories of the xʷməθkʷəy̓əm (Musqueam) people.

Asbestos – Environmental Exposures

Asbestos Environmental Exposures

Asbestos Environmental Exposures

Overview

In the environment, the primary route of exposure is by inhaling air contaminated with asbestos. People may be exposed to higher-than-average levels of asbestos in air if they use asbestos-containing products, or live or work in buildings with deteriorating asbestos insulation or that have undergone poorly performed asbestos removal.[1]

READ MORE...

People may also be exposed during home renovations if asbestos containing materials are disturbed. Asbestos was used in over 3,000 different building materials used from the 1950s to 1990s such as stucco, flooring, roof shingles, and insulation.[2,3]  Family members of asbestos workers may also be exposed through contaminated work clothing.[4]  CAREX Canada estimates that asbestos levels in indoor and outdoor air may result in increased risks of cancer at a population level (very low data quality).

Vermiculite insulation produced between the 1920s and 1990s and used in homes may contain amphibole asbestos and could be an exposure hazard if disturbed.[5]  Vermiculite products marketed for garden use may also contain asbestos. An EPA study in the Seattle area in 2000 found 5 of 16 purchased products were contaminated with asbestos.[6]

Although contaminated air is the most important route of exposure in the general population, people may also be exposed by ingesting drinking water in areas where asbestos occurs (either naturally or from human activities). There is a great deal of debate on the carcinogenic role (if any) of exposure to asbestos via drinking water. In general, there is no consistent evidence to support this hypothesis.[7,8]  CAREX Canada estimates that exposure to asbestos via drinking water or food and beverages is negligible.

Asbestos is geologically related to talc, a substance that may be used in cosmetics and pharmaceuticals, and as a food additive. Talc from some mine deposits can be contaminated with asbestos, especially anthophyllite and tremolite.[7]  When used as a food additive, talc must be asbestos free, as per the Food and Drug Regulations.[9]  The Prohibition of Asbestos and Products Containing Asbestos Regulations prohibits asbestos above trace levels in consumer products, including cosmetics.[10]  However, the responsibility of testing lies with the manufacturers.

Searches of Environment Canada’s National Pollutant Release Inventory (NPRI) and the US Household Products Database yielded the following results on current potential for exposure to asbestos in Canada:

NPRI and US Household Products Database

NPRI 2017[11]
Substance name: ‘Asbestos (friable form)’
CategoryQuantityIndustry
Released into EnvironmentNoneWaste treatment and disposal,
Remediation and waste management,
petroleum and coal product manufacturing
pesticide, fertilizer and other agricultural
chemical manufacturing,
oil and gas extraction
(50 facilities)
Disposed of24,126 t
Sent to off-site recycling28 t
t = tonne
US Household Products 2018[12]
Search TermQuantityProduct Type
‘chrysotile asbestos’5Roofing sealant cements
‘anthophyllite asbestos’4Paint primer

Cancer Risk Estimates

Potential lifetime excess cancer risk (LECR) is an indicator of Canadians’ exposure to known or suspected carcinogens in the environment. When potential LECR is more than 1 per million in a single pathway, a more detailed risk assessment may be useful for confirming the need to reduce individual exposure. If measured levels of asbestos in relevant exposure pathways (outdoor air and indoor air) decrease, the risk will also decrease.

Potential LECR due to exposure to asbestos is calculated by multiplying lifetime hourly concentration by a unit risk factor. More than one cancer potency factor may be available, because agencies interpret the underlying health studies differently, or use a more precautionary approach. Our results use unit risk factors from Health Canada, the US Environmental Protection Agency (US EPA), and/or the California Office of Environmental Health Hazard Assessment (OEHHA).

The calculated lifetime hourly concentrations and LECR results for asbestos are provided in the tables below. For more information on supporting data and sources, click on the Methods and Data tab below.

Calculated Lifetime Hourly Concentrations

Lifetime Excess Cancer Risk (per million people)

*LECR based on average intake x cancer potency factor from each agency

Compare substances: Canadian Potential Lifetime Excess Cancer Risk, 2011

The data in this table are based on average intake and Health Canada’s cancer potency factor, assuming no change in measured levels. When Health Canada values are not available, United States Environmental Protection Agency values are used.
Click the second tab to view LECR data. 


**Exposure not applicable: For indicated pathways, substance not present, not carcinogenic, or exposure is negligible
**Gap in data: No cancer potency factor or unit risk factor, or no data available
IARC Group 1 = Carcinogenic to humans, IARC Group 2A = Probably carcinogenic to humans, IARC Group 2B = Possibly carcinogenic to humans

NOTE: Chromium (hexavalent) estimates assume that 5% of total chromium measured in outdoor air is hexavalent and 8% total chromium measured in indoor dust is hexavalent. 

Potential LECR assumes exposure occurs at the same level, 24 hours per day, for 70 years. This is rarely true for any single individual, but using a standard set of assumptions allows us to provide a relative ranking for known and suspected carcinogens across different exposure routes. While ongoing research continually provides new evidence about cancer potency and whether there is a safe threshold of exposure, our approach assumes there are no safe exposure levels.

Mapping

Exposure to asbestos may have occurred historically in communities close to asbestos mines, and may still be occurring when waste piles containing asbestos are present.[13,14,15] In the past, people who lived near manufacturing facilities producing insulation with asbestos-contaminated vermiculite from Libby, Montana may have been exposed;[16,17,18] and recent studies also suggest that exposure might occur when naturally occurring asbestos deposits are disturbed.[19] Vermiculite produced by the Libby Mine in Montana from the 1920s-1990 and sold as Zonolite® Attic Insulation may contain amphibole asbestos,[20] and potential exposures may occur in homes where Zonolite® insulation is disturbed.

Selected Asbestos Mines, Historic Vermiculite Processing Facilities and Potential Naturally Occurring Asbestos Deposits

Canadian Distribution of Libby Ore Shipments from 1964-1990 (in tons)[21]

 

Asbestos Production

Exposure to asbestos may have occurred historically in communities close to asbestos mines, and may still be occurring when waste piles containing asbestos are present.[12,13,14] In the past, people who lived near manufacturing facilities producing insulation with asbestos-contaminated vermiculite from Libby, Montana may have been exposed;[15,16,17] and recent studies also suggest that exposure might occur when naturally occurring asbestos deposits are disturbed.[18] Vermiculite produced by the Libby Mine in Montana from the 1920s-1990 and sold as Zonolite® Attic Insulation may contain amphibole asbestos,[19] and potential exposures may occur in homes where Zonolite® insulation is disturbed.

The last two operating asbestos mines in Canada – both in Quebec – closed down in 2012.

Annual Asbestos Production in Canada: 1886 to 2011[22,23,24]

*Data not available in 1987 for QC, BC, NL

Known asbestos producers and mine locations in Canada 1943 to 2006[23]

Vermiculite Processing

In 1916, the world’s largest deposit of vermiculite was discovered near Libby, Montana. The vermiculite was mined primarily for use as an insulating material. Crude (or raw) vermiculite was shipped from the mine to processing plants across the US and in Canada, where it was exfoliated using high temperatures causing it to expand significantly. In 1935, a report from the US Bureau of Mines noted the presence of a series of amphibole asbestos dikes, up to 10 feet thick intersecting the vermiculite deposit. Over the entire operating life of the Libby mine (1921 to 1992), the vermiculite extracted and shipped for processing was contaminated with this particularly carcinogenic form of asbestos.[23,25]

Vermiculite was mined and processed commercially in Canada only for a very short time (1956, 1957, and 1966) and in very small quantities at a location near Stanleyville, Ontario. All other vermiculite processed in Canada was imported from the United States, predominantly from Libby mine, or from South Africa (presumed to be uncontaminated).

Available data sources regarding Canadian imports of vermiculite include: 1) general information on all imports to Canada from South Africa or the United States reported in mineral yearbooks from the United States Geological Survey and Natural Resources Canada, and (2) invoices of vermiculite shipments from the Libby Montana Mine to companies in Canada from the United States Environmental Protection Agency. See more information about each data source below.

 
Canadian Imports Reported in Mineral Yearbooks (CAN & US)

The graph below shows tonnes of crude vermiculite imported from the US and South Africa for years with available data. USGS Bureau of Mines reports note that vermiculite from the Libby mine was being exported to Canada for processing as early as 1935 (Winnipeg, MB and Paris, ON).[25] See the map for more information on processing sites in Canada.

Annual Imports of Crude Vermiculite: 1963 to 1992[23,25]

Libby Mine Invoices

The United States Environmental Protection Agency (EPA) has compiled a database documenting W.R. Grace invoices for shipments from the Libby Mine from 1964 to 1990.[26] The database includes company name, shipping destination, and total tonnage shipped. The EPA database may not include every shipment made during this time.

Although the number of sites and amount of ore received may be understated by invoices in the database, the EPA has investigated sites in the United States thought to have received ore to determine if remediation activities are necessary. Investigations have not been carried out for Canadian shipment locations.

The following table reports W.R. Grace invoices for shipments of vermiculite from Libby Mine to Canadian locations from the EPA database. No information is available on the end uses of vermiculite shipped to reported Canadian locations; some may have been shipped directly to facilities engaged in vermiculite processing, while others may have been subsequently transported to other locations for other intended purposes.

At least 8,252 shipments of vermiculite were made from Libby, MT to locations in Canada; the majority of shipments and total tons to Ontario, Quebec, and Alberta. See the table below and map for more information on shipment locations in Canada.

Total Number of Shipments from Libby, MT to Canada: 1964-1990

Invoices from Libby, MT to Canadian Locations: 1964-1990

Home Insulation

The number of homes in Canada insulated using Zonolite® is unknown; however, it is estimated to be present in 3% of low-rise houses across Canada, or 242,000 homes in residential neighbourhoods, including First Nation Housing, and on Canadian military bases.[27]

From 1977-1986 the Canadian Home Insulation Program (CHIP) provided grants to homeowners for improving the energy efficiency of their homes. During this time 2,592,392 grants were issued for approximately 150 different types and brands of insulation products, including Zonolite® vermiculite insulation.[28] The actual number of homes which insulated using Zonolite® under the program is unknown, as CHIP was instituted prior to digital record-keeping. Existing paper records may contain information on a residence-by-residence basis on the products purchased under the grant to upgrade home insulation. These paper records may indicate potential exposure in homes that were insulated with Zonolite®, but would not reflect those that have since been remediated.

Indian and Northern Affairs Canada (INAC) has reviewed their records to attempt to identify where vermiculite insulation containing asbestos may have been used in the construction of houses on reserves.[29] Of houses built between 1960-1990, INAC found 597 references to houses that may have been built using Zonolite® Loose-Fill Vermiculite Insulation in the provinces of Saskatchewan (276), Manitoba (234), British Columbia (28), Quebec (28), and Alberta (5). An additional 6 references in the Yukon identified the use of vermiculite in general, but not specifically the Zonolite® brand. No records were available for the Northwest Territories of Nunavut, as housing is under the jurisdiction of Territorial Governments.

The Department of National Defence has assessed their complete housing portfolio.[27]

Health Canada has posted extensive information about vermiculite insulation that may contain asbestos on their website.[20]

Methods and Data

Our Environmental Approach page outlines the general approach used to calculate lifetime excess cancer risk estimates and includes documentation on our mapping methods. The documents below outline (1) the specific methods for asbestos lifetime excess cancer risk estimate calculations and (2) the data sources and data quality for asbestos estimates.

(1) LECR Methods – Asbestos [PDF]

(2) Supplemental data – Asbestos [PDF]

Sources

1. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Asbestos, US Dept. of Health & Human Services (2001) (PDF)
2. WorkSafeBC. Asbestos
4. Donovan EP, Donovan BL, McKinley MA, Cowan DM, Paustenback DJ.“Evaluation of take home (para-occupational) exposure to asbestos and disease: a review of the literature.” Crit Rev Toxicol 2012;42(9):703-730.
7. National Toxicology Program (NTP). 14th Report on Carcinogens for Asbestos (2016) (PDF)
8. World Health Organization (WHO). Asbestos in Drinking Water (2003) (PDF)
9. Environment and Climate Change Canada and Health Canada . Draft screening assessment talc (Mg3H2(SiO3)4) (2018)
11. Environment and Climate Change Canada. National Pollutant Release Inventory (NPRI) Facility Search (Substance name: ‘Asbestos (friable form)’)
12. Consumer Product Information Database (CPID).What’s in it? (2022) (Search term: ‘Asbestos’)
14. Institut national de santé publique du Québec. Asbestos Fibres in Indoor and Outdoor Air: The Situation in Quebec (2003) (PDF)
15. Marier M, Charney W, Rosseau R, Lanthier R, Van Raalte, J. “Exploratory Sampling of Asbestos in Residences Near Thetford Mines: The Public Health Threat in Quebec”. Int J Occup Environ Health 2007;13(4):386-397.
16. Alexander BH, Raleigh KK, Johnson J, Mandel, JH, Adegate, JL, Ramachandran G, Messing RB, Eshenaur T, Williams A. “Radiographic Evidence of Nonoccupational Asbestos Exposure from Processing Libby Vermiculite in Minneapolis, Minnesota.” Environ Health Perspect 2012;120(1):44-49.
17. Elashheb MI, Spear TM, Hart JF, Webber JS, Ward TJ. “Libby Amphibole Contamination in Tree Bark Surrounding Historical Vermiculite Processing Facilities.” J Environ Protection 2011;2(8):1062-1068.
18. Kelly J, Pratt GC, Johnson J, Messing RB. “Community Exposure to Asbestos from a Vermiculite Exfoliation Plant in NE Minneapolis.” Inhal Toxicol 2006;18(12):941-947.
19. Unites States Environmental Protection Agency Region 9. Naturally Occurring Asbestos: Clear Creek Management Area (2008)
21. Unpublished data from an EPA database of W.R. Grace invoices for shipments of vermiculite from the Libby mine from 1964 through 1990.
22. Statistics Canada. Non-metallic Minerals (1886 to 1975)
23. Natural Resources Canada. Minerals Yearbook (1941 to 2010)
24. US Geological Survey. 2013 Minerals Yearbook – Asbestos (2014) (PDF)
25. United States Geological Survey. Bureau of Mines Minerals Yearbooks (1931 to 1992)
26. Unpublished data from an EPA database of W.R. Grace invoices for shipments of vermiculite from the Libby mine from 1964 through 1990.
27. The Canadian Real Estate Association. Vermiculite Insulation and Asbestos (2007) (PDF)
28. Parliament of Canada. Question No. 620 Response by David Anderson (2012) (PDF)
29. Aboriginal Affairs and Northern Development Canada. Information on Vermiculite Insulation Containing Asbestos (2010)

Subscribe to our newsletters

The CAREX Canada team offers two regular newsletters: the biannual e-Bulletin summarizing information on upcoming webinars, new publications, and updates to estimates and tools; and the monthly Carcinogens in the News, a digest of media articles, government reports, and academic literature related to the carcinogens we’ve classified as important for surveillance in Canada. Sign up for one or both of these newsletters below.

CAREX Canada

School of Population and Public Health

University of British Columbia
Vancouver Campus
370A - 2206 East Mall
Vancouver, BC  V6T 1Z3
CANADA

© 2025 CAREX Canada
Simon Fraser University

As a national organization, our work extends across borders into many Indigenous lands throughout Canada. We gratefully acknowledge that our host institution, the University of British Columbia Point Grey campus, is located on the traditional, ancestral, and unceded territories of the xʷməθkʷəy̓əm (Musqueam) people.

Asbestos – Occupational Exposures

Asbestos Occupational Exposures

Asbestos Occupational Exposures

Overview

Inhalation is the most important route of occupational exposure to asbestos.[1] CAREX Canada estimates that approximately 235,000 Canadians are exposed to asbestos in their workplace. Current asbestos-related disease is associated with exposures that occurred 10 to 40 years ago. This is due to the latency period between exposure and onset of disease. The exposure sources were very different at that time than they are now.

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Exposure from more widespread mining and milling, in addition to primary use of asbestos in manufactured products and buildings was most important in the past. According to the Burden of Occupational Cancer in Canada project, past exposures (1961-2001) to asbestos leads to approximately 1,900 lung cancers and 430 mesotheliomas each year [2,3]. This amounts to 8% of all lung cancers and 81% of all mesotheliomas diagnosed annually (almost all of the remaining mesotheliomas are likely due to environmental asbestos exposure). Most asbestos-related cancers occur among workers in the manufacturing and construction sectors. Work-related asbestos exposure resulted in approximately $2.35 billion in costs for newly diagnosed lung cancer and mesothelioma cases in 2011[4].

In contrast, the vast majority of exposure that occurs today is due to contact with older asbestos-containing products, and doing renovation work on buildings and in industrial plants. These exposures can be considered as a kind of secondary exposure from contact with those products and building materials that were made or put in place more than 35 years ago.

Many of the workers currently expected to be exposed work in the construction sector, where exposure occurs from poor exposure control during renovation and refurbishing of old buildings. Exposure in construction workers is difficult to monitor due to the wide variety of worksites and the transient nature of employment for many workers. Despite this, the INSPQ in Quebec released a report on exposures to asbestos in the construction industry.[5]

In addition, exposure may commonly occur among maintenance workers in industries where substantial amounts of asbestos were used in the past (such as smelting, petroleum refining and pulp and paper), as well as automotive brake repair workers, and people that repair and maintain ships.

In some cases, we expect to see exposure today in the same or similar occupational groups as we did in the 1970s (i.e. construction workers, plumbers and pipefitters), albeit at lower exposure levels. In other cases, such as in mining, exposure has been almost completely phased out. Further, the abatement and asbestos remediation industry is an entire category of business with potential for exposure to asbestos that did not exist as a separate profession until the early 1980s.

CAREX Canada estimates that the largest occupational groups exposed are carpenters, construction trades helpers and labourers, electricians, and janitors, caretakers and building superintendents.

Prevalence Estimate

Using an approach that considered historical uses of exposure in Canada to guide exposure assessments for the present day, results indicate that approximately 235,000 Canadians are currently exposed to asbestos in their workplaces, and are primarily male (89%). This estimate includes people with the potential for exposure at work to any form of asbestos likely to exceed the non-occupational background level in dwellings or urban air (usually below 0.001 f/cm3).

The largest industrial groups exposed are construction-related (specialty trades and building construction contribute about 67% of all exposed workers). Other important industries include public administration, schools, and hospitals.

When examining exposure to asbestos by occupation, the largest exposed groups are carpenters (36,000 workers exposed), construction trades helpers and labourers (36,000 workers exposed), electricians (21,000 workers exposed), and janitors, caretakers and building superintendents (19,000 workers exposed).

The number of workers exposed to asbestos increased by approximately 83,000 workers from 2006 to 2016 (a 55% increase). This was primarily driven by the identification of additional occupations where exposure may occur, including in educational services, hospitals, nursing and residential care facilities, social assistance, and public administration industries.

Workers exposed to asbestos by industry in 2016

Workers exposed to asbestos by region in 2016

Click the second tab to view total number of workers exposed.

Level of Exposure

In total, approximately 235,000 Canadians are exposed to asbestos in their workplaces. The majority of workers exposed to asbestos are in the low and moderate exposure categories. A significant number of asbestos-exposed workers are at risk for high exposure.

Workers exposed to asbestos by exposure level in 2016

Level of exposure by industry

Identifying industries with either 1) workers exposed to high levels of asbestos or 2) a larger number of workers exposed to asbestos is important in guiding cancer prevention efforts to prioritize exposed groups and target resources most effectively.

The table below shows the number of workers exposed by industry group and level of exposure to asbestos. These results highlight industries with the most number of workers, as well as industries with the highest levels of exposure. For example, in the specialty trade contractors and construction of building industries, a large number of workers are exposed, with many exposures occurring in the moderate and high exposure categories. Depending on the goals of a prevention campaign, exposure reduction in the large industrial group might be a useful strategy, or reducing exposure to those at highest risk of exposure could be seen as a priority.

Workers exposed to asbestos by exposure level and industry in 2016

*Numbers may not add up due to rounding

Methods and Data

Our Occupational Approach page outlines the general approach used to calculate prevalence and exposure level estimates for workplace exposures.

Data Sources

Data used in developing the occupational estimates for asbestos were collected from several sources:

  1. The Canadian Workplace Exposure Database (CWED) contains approximately 6,700 measurements for asbestos exposure. These measurements were collected during the years 1981 to 2004 in Ontario and British Columbia workplaces.
  2. Canadian and US scientific peer reviewed publications that addressed asbestos exposure in Canada and the United States.
  3. Grey literature including technical reports from governments and international bodies.

Prevalence Estimate Method

CAREX defines exposure to asbestos as inhalation at work to levels significantly exceeding non-occupational background levels.

To determine the number of workers potentially exposed to asbestos at work, CAREX occupational exposure experts used methods previously established in other peer-reviewed CAREX projects in Europe. A series of steps were taken to assign exposure proportions to occupations and industries at risk of exposure to asbestos.

  1. Occupations and industries at risk of possible exposure to asbestos were identified using any combination of data sources described above.
  2. The total number of workers in each identified occupation and industry intersection was obtained from Statistics Canada 2016 census data.
  3. A percentage of workers exposed was assigned to that occupation and industry intersection. Percentages were determined by consultation with existing evidence in the data sources, previously established methods from the Europe CAREX estimates and the expert judgement of CAREX occupational hygienists.
  4. The number of workers in the identified group is multiplied by the assigned percentage to calculate the prevalence estimate of workers exposed to asbestos.
Sources

1. National Toxicology Program (NTP). 14th Report on Carcinogens for Asbestos (2016) (PDF)
2. Labrèche F, Kim J, Song C, Pahwa M, Calvin BG, Arrandale VH, McLeod CB, Peters CE, Lavoué J, Davies HW, Nicol AM. “The current burden of cancer attributable to occupational exposures in Canada.” Prev Med 2019;122:128-39.
3. Occupational Cancer Research Centre. Burden of Occupational Cancer (2017)
4. Tompa E, Kalcevich C, McLeod C, Lebeau M, Song C, McLeod K, Kim J, Demers PA. “The Economic Burden of Lung Cancer and Mesothelioma Due to Occupational and Para-Occupational Asbestos Exposure.” Occup Environ Med 2017;74(11):816-822.

  

Subscribe to our newsletters

The CAREX Canada team offers two regular newsletters: the biannual e-Bulletin summarizing information on upcoming webinars, new publications, and updates to estimates and tools; and the monthly Carcinogens in the News, a digest of media articles, government reports, and academic literature related to the carcinogens we’ve classified as important for surveillance in Canada. Sign up for one or both of these newsletters below.

CAREX Canada

School of Population and Public Health

University of British Columbia
Vancouver Campus
370A - 2206 East Mall
Vancouver, BC  V6T 1Z3
CANADA

© 2025 CAREX Canada
Simon Fraser University

As a national organization, our work extends across borders into many Indigenous lands throughout Canada. We gratefully acknowledge that our host institution, the University of British Columbia Point Grey campus, is located on the traditional, ancestral, and unceded territories of the xʷməθkʷəy̓əm (Musqueam) people.

Asbestos – Resources

Asbestos Resources

Package summaries

Fact sheets – Burden of Occupational Cancer

Tools

Publications

Videos

Other

Exposure Reduction

Our team has performed a detailed scan of exposure control resources and assembled a compilation of key publications and resources. These are organized by type of exposure (environmental or occupational) and by specificity (general or carcinogen-specific). Please visit our Exposure Reduction Resources page to view.

We also recommend exploring the Prevention Policies Directory, a freely-accessible online tool offering information on policies related to cancer and chronic disease prevention. Providing summaries of the policies and direct access to the policy documents, the Directory allows users to search by carcinogen, risk factor, jurisdiction, geographical location, and document type. For questions about this resource, please contact a member of the Prevention Team at the Canadian Partnership Against Cancer at [email protected].

Subscribe to our newsletters

The CAREX Canada team offers two regular newsletters: the biannual e-Bulletin summarizing information on upcoming webinars, new publications, and updates to estimates and tools; and the monthly Carcinogens in the News, a digest of media articles, government reports, and academic literature related to the carcinogens we’ve classified as important for surveillance in Canada. Sign up for one or both of these newsletters below.

CAREX Canada

School of Population and Public Health

University of British Columbia
Vancouver Campus
370A - 2206 East Mall
Vancouver, BC  V6T 1Z3
CANADA

© 2025 CAREX Canada
Simon Fraser University

As a national organization, our work extends across borders into many Indigenous lands throughout Canada. We gratefully acknowledge that our host institution, the University of British Columbia Point Grey campus, is located on the traditional, ancestral, and unceded territories of the xʷməθkʷəy̓əm (Musqueam) people.