IARC assesses whether some nanomaterials and fibres cause cancer

As part of our ongoing surveillance of Canadians exposures to carcinogens, the CAREX team monitors evaluations by the International Agency for Research on Cancer (IARC). In October 2014, IARC gathered 21 experts from 10 countries to evaluate whether a selection of nanomaterials and fibers cause cancer.

The expert team looked specifically at fluoro-edenite, silicon carbide fibres and whiskers, and carbon nanotubes (including single-walled and multi-walled varieties). A summary of their conclusions for each nanomaterial is summarized below.

Silicon carbide:

  • Occupational exposures associated with manufacturing silicon carbide particles, called the Acheson process, were classified as carcinogenic (Group 1) based on sufficient evidence that they cause lung cancer in humans.
  • Fibrous silicon carbide was classified as possibly carcinogenic (Group 2B) based on limited evidence in humans that it causes lung cancer.
  • Silicon carbide whiskers were classified as probably carcinogenic to humans (Group 2A), rather than possibly carcinogenic to humans (Group 2B), because the physical properties of the whiskers resemble those of asbestos fibres, which are known carcinogens.

Virtually all the silicon carbide sold in the world is manufactured. This substance occurs in three forms: particles that are used in industry as an abrasive, fibres that are a by-product of particle manufacturing, and whiskers that are used as durable substitutes for asbestos.

Fluoro-edenite fibres:

  • These fibres were classified as carcinogenic (Group 1) based on sufficient evidence that human exposure causes mesothelioma.

Fluoro-edenite is a mineral that can take the form of fibres similar to asbestos. Quarry products from Biancavilla in Italy, used to make unpaved roads in the area since the 1950s, are a source for airborne fluoro-edenite fibres. Exposures have also occurred via indoor air, as a result of the quarry’s products being used in building materials.

Carbon nanotubes:

  • A specific nanotube, multi-walled carbon nanotube-7 was classified as possibly carcinogenic(Group 2B) based on evidence showing that they caused mesotheliomas in male and female rats.
  • All other multi-walled and single-walled carbon nanotubes were categorised as not classifiable as to their carcinogenicity to humans (Group 3) due to insufficient evidence.

Carbon nanotubes consist of either a single cylinder of carbon (single-walled), with an outer diameter of 1–3 nm, or of multiple carbon cylinders arranged in layers (multi-walled) with diameters of 10–200 nm. The characteristics of carbon nanotubes vary depending on how they’re produced. They can be used to improve the structural integrity of fabrics, plastics, rubbers, electronics (i.e. in transistors and solar cells), and structural materials, as well as in medicine (i.e. drug delivery and bone tissue engineering). More information can be found on our carbon nanotubes profile.

The full IARC Monograph Volume 111: Some Nanomaterials and Some Fibres is available here.

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CAREX Canada

School of Population and Public Health

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

© 2022 CAREX Canada
Simon Fraser University

New results for levels and burden of exposure to diesel exhaust in workplaces

mine shaftThanks to a collaborative effort with scientists from the Occupational Cancer Research Centre, our occupational exposures team was able to estimate the levels of exposure to diesel engine exhaust in Canadian workplaces. Results show the majority of workers exposed to diesel exhaust are in the low exposure category, with a significant number at risk for moderate to high exposure.

Diesel exhaust is a known carcinogen and among the most prevalent occupational exposures in Canada; our estimates show that approximately 897,000 Canadians are exposed to diesel exhaust at work. In mining-related industries, where underground work increases the possibility for exhaust to accumulate, the majority of exposed workers fall into the highest exposure category. In transportation industries, the majority of exposed workers are in the low exposure category.

A summary of exposure level results by industry is available under the Levels of Exposure for diesel engine exhaust on our website. The approach used to calculate levels is described under the Data Sources and Methods tab.

These estimates were used to inform initial estimates for burden of workplace exposure to diesel exhaust.

Our partners at the Occupational Cancer Research Centre recently presented preliminary results on the burden of workplace exposure to diesel engine exhaust, upgraded in 2012 to a known human carcinogen. This work is part of a major project funded by the Canadian Cancer Society to apply CAREX Canada estimates to calculate the current burden of occupational cancers in Canada.

Estimates show that between 1961-2001, approximately 1.4 million Canadian workers were exposed to diesel engine exhaust at work. Preliminary calculations show that the proportion of new cancer cases and cancer deaths that can be attributed to this exposure is: 4.92% for males, 0.29% for females, and 2.70% overall. These estimates are somewhat higher than those reported by a recent occupational cancer burden project in Great Britian (1.3-1.8%). The Canadian estimates were developed using the most recent evidence for the risk of lung cancer from occupational exposure to diesel engine exhaust, as well as detailed historical exposure assessment for diesel exhaust from CAREX Canada and detailed labour force models.

More information about this project can be found on our Burden of Cancer page and on OCRC’s website.

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

© 2022 CAREX Canada
Simon Fraser University