A ban on asbestos must be based on a comparative risk assessment

Our plain-English summary of A ban on asbestos must be based on a comparative risk assessment, by M. Camus (CMAJ, 2001).

The study

• Author: M. Camus
• Journal: CMAJ
• Published: 2001;164(4):491-4
• Type of article: Comment, Review
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Free full text

Summary of the article

This commentary responded to a call by the Collegium Ramazzini for an immediate and total ban on asbestos products. The author, of Health Canada, argued that the Collegium exaggerated the risks of chrysotile by relying on a single cohort of chrysotile textile workers that may be an unrepresentative outlier. He also argued that the Collegium's statements on controlled use and substitutes were supported neither by evidence nor by references. Citing risk assessments covering 47 cohorts of asbestos workers, he reported that, for an equal number of expected cases, excess lung cancers occurred 3 times, pleural mesothelioma 12 times and peritoneal mesotheliomas 30 times more frequently in mainly amphibole than in chrysotile industries. He also reported that chrysotile workers were 4–24 times less at risk of asbestos-induced lung cancer than amphibole workers at equal exposure. He estimated that lifetime risks of asbestos-related death in today's chrysotile-exposed workers, whose controlled exposures were about 1000 times lower than in the past, should be less than 1–5 per 100 000 lives. He reviewed evidence that substitutes, including glass and ceramic fibres, rock and slag wools, p-aramid and cellulose, may also carry health risks, and raised concerns about substitute performance in pipes and brakes. He stated that a ban would not address the main cause of the mesothelioma epidemic, which he identified as existing friable amphibole-containing products in buildings. He concluded that any ban should follow a comparative risk assessment applying the precautionary principle equally to chrysotile and its substitutes.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This is a commentary, not an original study. The author, from Health Canada and writing personal views, responded to a call by Joseph LaDou and colleagues for the Collegium Ramazzini for an immediate and total ban on asbestos. The author argued that the Collegium estimated chrysotile risk from a single cohort of chrysotile textile workers that may be an unrepresentative outlier. Citing earlier risk assessments of 47 asbestos worker cohorts, the author reported that excess lung cancers occurred 3 times, pleural mesothelioma 12 times and peritoneal mesothelioma 30 times more frequently in mainly amphibole than in chrysotile industries, for an equal number of expected cases. The author noted that glass and ceramic fibres, silicon carbide whiskers, and rock and slag wools, which are chrysotile substitutes, had been classified as possible or probable carcinogens. The author also noted that exposure standards allowed 5–20 times more exposure to glass, rock and slag wools than to chrysotile. The author concluded that any ban should follow a comparative risk assessment of chrysotile and its substitutes.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Commentary (opinion piece) responding to another article; no original data collected
• Who was studied: No study population. The commentary responds to the Collegium Ramazzini's call for a ban (LaDou and colleagues, same CMAJ issue) and discusses published worker cohorts, risk assessments and studies of substitutes.
• Exposure: Chrysotile compared with amphibole asbestos (tremolite, amosite, crocidolite), and chrysotile substitutes: p-aramid, polyvinyl alcohol (PVA), cellulose, polyacrylonitrile, glass fibres, graphite, polytetrafluoroethylene, ceramic fibres and silicon carbide whiskers
• Main results:
  • The author argued that the Collegium based its chrysotile risk estimate on a single cohort of chrysotile textile workers that may be an unrepresentative outlier.
  • Citing 47 cohorts reviewed in earlier risk assessments (not this article's own data): for an equal number of expected cases, excess lung cancers occurred 3 times, pleural mesothelioma 12 times and peritoneal mesothelioma 30 times more frequently in mainly amphibole industries than in chrysotile industries.
  • Citing exposure–response comparisons from other studies: chrysotile workers were 4–24 times less at risk of asbestos-induced lung cancer than amphibole workers at equal exposure.
  • Citing the author's own earlier research on residents of chrysotile mining towns: the lung cancer risk implied was at least 15 times smaller, and the number of mesotheliomas observed at least 20 times smaller, than predicted by the EPA model.
  • The author estimated, from exposures about 1000 times lower than in the past, that lifetime risks of asbestos-related death in today's chrysotile-exposed workers were less than 1–5 per 100 000 lives, 20–100 times less than the Collegium's estimate.
  • The author noted that some chrysotile substitutes had been classified by the International Agency for Research on Cancer as possible or probable carcinogens.
  • Citing a European cohort study (not this article's own data): rock and slag wool workers had a dose-related excess of oral, pharyngeal and laryngeal cancers (RR 1.5, 95% CI 1.0–2.1). The similar relationship for glass wool workers (RR 1.4, 95% CI 0.8–2.3) was not statistically significant.
  • The author noted that health standards tolerated 5–20 times more exposure to glass, rock and slag wools than to chrysotile fibres.
• The authors' conclusion: The author concluded that a ban on asbestos should be assessed using a comparative risk approach before being adopted, applying the precautionary principle equally to chrysotile and its substitutes. The author argued that the proposed ban could otherwise do more harm than good.
• Limitations the authors state:
  • The author stated that the commentary did not consider the cost of sanitation piping for developing nations or the transfer of jobs from asbestos-producing countries.
  • The author stated that the paper presents personal views that do not necessarily reflect Health Canada's views or policies.

Topics

Medical terms in this study, explained in our Lexicon: Collegium Ramazzini, Chrysotile, Controlled Use, Lung Cancer, Pleural Mesothelioma, Peritoneal Mesothelioma, Amphibole Group, Mesothelioma.

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• A ban on asbestos: is now the time? — (2001)
• Asbestos is still with us: Repeat call for a universal ban — C. Ramazzini (2011)
• The contribution of environmental monitoring in the epidemiological assessment of exogenous risk. The experience of ARPA in the Emilia-Romagna Region of Italy — A. Zavatti, P. Lauriola (1999)
• Quality of evidence must guide risk assessment of asbestos — V. Lenters, A. Burdorf, et al. (2012)
• Quality of evidence must guide risk assessment of asbestos, by Lenters, V; Burdorf, A; Vermeulen, R; Stayner, L; Heederik, D — J.T. Hodgson (2013)

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