Chrysotile asbestos revisited

Our plain-English summary of Chrysotile asbestos revisited, by J. Dunnigan (British Journal of Industrial Medicine, 1993).

The study

• Author: J. Dunnigan
• Journal: British Journal of Industrial Medicine
• Published: 1993;50(9):862-3
• Type of article: Letter
• Read it: PubMed · Publisher · Free full text

In plain English

This letter to the editor, from the University of Sherbrooke, Quebec, presented no original study but discussed other researchers' work. It described preliminary 1992 results, then unpublished, from an updated cohort of Quebec chrysotile miners and millers. With 7312 deaths, that study's authors could not detect excess lung cancers in six exposure classes up to 300 mpcf years. At about 3 f/ml per mpcf, the author put this at 900 f/ml years, about 45 f/ml for 20 years. The author wrote that this should not be read as inviting relaxation of the 1 f/ml chrysotile limit recommended by World Health Organisation experts in 1989. The letter argued that animal studies used unequal doses, such as 10 000 f/ml of chrysotile versus about 250 f/ml of man made vitreous fibres in one rat study. It also cited a hamster lung cell study and a rat study of mesothelioma after fibre injection; both found chrysotile less potent per fibre than crocidolite and erionite. The author concluded that a major international re-evaluation of chrysotile, comparing fibres by fibre number, was in order.

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: Letter to the editor (correspondence) giving the author's views on other published and presented studies; no original study
• Who was studied: No population of its own. The letter discussed a cohort of Quebec chrysotile miners and millers (preliminary update presented in Cincinnati in September 1992), plus rat inhalation and injection studies and an in vitro study on Chinese hamster lung cells
• Exposure: Chrysotile asbestos, compared with man made vitreous fibres (MMVFs), refractory ceramic fibre, aramid (Kevlar) fibres, crocidolite and erionite; the letter focused on dose expressed as fibre number rather than mass
• Main results:
  • In the Quebec chrysotile cohort update described in the letter, follow up ran to May 1992 and added 2827 deaths, bringing the total to 7312
  • In that cohort, the study's authors were unable to detect any excess lung cancers for six exposure classes up to 300 mpcf years (preliminary results)
  • Using a conversion of about 3 f/ml per mpcf, the letter's author calculated that the levels below which no excess lung cancers were detected would be 900 f/ml years, or about 45 f/ml for 20 years
  • In a cited rat inhalation study, the animals were exposed for 24 months to about 250 f/ml of MMVFs, 180 f/ml of refractory ceramic fibre and 10 000 f/ml of chrysotile asbestos, according to the letter
  • A cited report found that rats given 100 f/ml of aramid fibres for 24 months developed fibrosis and cystic keratinising squamous tumours
  • A cited 1988 in vitro study on Chinese hamster lung cells found that, counted by fibre number, chrysotile needed more than 50 times as many fibres as crocidolite, and more than 300 times as many as erionite, for similar cytotoxic effects
  • A cited rat study by Coffin et al on mesothelioma after intrapleural and intratracheal injection found erionite 500 to 800 times, and crocidolite 30 to 60 times, more tumorigenic than chrysotile per fibre
• The authors' conclusion: The author concluded that chrysotile asbestos should be revisited and compared with other fibres at comparable fibre-number doses, and that a major international re-evaluation of chrysotile was in order. The author also wrote that the cohort data indicated the recommended 1 f/ml limit was realistic and acceptable.
• Limitations the authors state:
  • The author noted that the cohort results were a preliminary report awaiting full publication and should not be read as an invitation to relax the 1 f/ml exposure limit for chrysotile

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Chrysotile.

Related studies

• Health risk of chrysotile revisited — D. Bernstein, J. Dunnigan, et al. (2013)
• Response to Murray M. Finkelstein, letter to the editor re Bernstein et al: Health risk of chrysotile revisited. Crit Rev Toxicol, 2013; 43(2): 154-183 — D. Bernstein, J. Dunnigan, et al. (2013)
• Letter to the Editor re Bernstein et al: Health risk of chrysotile revisited. Crit Rev Toxicol, 2013; 43(2): 154-183 — M.M. Finkelstein (2013)
• An epidemiological study of the role of chrysotile asbestos fibre dimensions in determining respiratory disease risk in exposed workers — L. Stayner, E. Kuempel, et al. (2008)
• How conflicted authors undermine the World Health Organization (WHO) campaign to stop all use of asbestos: spotlight on studies showing that chrysotile is carcinogenic and facilitates other non-cancer asbestos-related diseases — X. Baur, C.L. Soskolne, et al. (2015)
• Effect of kerosene and its soot on the chrysotile-mediated toxicity to the rat alveolar macrophages — J.M. Arif, S.G. Khan, et al. (1997)

Browse more research in British Journal of Industrial Medicine, or return to medical research.