The defence of chrysotile, 1912-2007

Our plain-English summary of The defence of chrysotile, 1912-2007, by M. Greenberg (International Journal of Occupational and Environmental Health, 2008).

The study

• Author: M. Greenberg
• Journal: International Journal of Occupational and Environmental Health
• Published: 2008;14(1):57-66
• Type of article: Historical article
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The commercial exploitation of asbestos may be dated from the late 1870s, when Canada was the major world source. Reports of severe and fatal respiratory disease in workers in asbestos factories appeared in Britain (1898, 1906), and in France (1906) and Italy (1908). In 1912 the Canadian Department of Labour denied that the health of Quebec's millers and miners was affected. A series of denials appeared for over 40 years, until in 1955 a Thetford Mines medical officer reported finding that between 1945 and 1953, among some 4,000 asbestos workers 128 had asbestosis of various degrees of severity, 121 diagnosed radiographically, and 33 confirmed at autopsy. Although a committee of inquiry into health in the asbestos industry (1976), and a Royal Commission on health and safety arising in the use of asbestos in Ontario (1984) confirmed that disease had occurred, these findings were to have no adverse effects on asbestos exports. Rather, the inquiries constituted elements in the industry's successful public relations exercise that continues to operate to this day. Even when an increasing number of national bodies have legislated for total bans on asbestos use, a policy with which all the international bodies concerned with public health agree, the Canadian PR apparatus continues to be able to call on physicians and scientists prepared to oppose the consensuses reached by the independent advisors to these bodies.

In plain English

This article was a historical review, not a new study. The author traced how Quebec chrysotile asbestos was defended as safe to mine and use from 1912 to 2007, including through Quebec's 1976 inquiry and Ontario's later Royal Commission. A 1940 Johns-Manville medical officer found X-ray signs of "early asbestosis" in 17 of 507 current workers employed over ten years and "moderate asbestosis" in 5, but dismissed the X-ray findings as irrelevant and concluded there had been no case of asbestosis. In 1955 a Thetford Mines medical officer reported that among some 4,000 workers, 128 had asbestosis, 121 diagnosed by X-ray and 33 confirmed at autopsy. The Quebec inquiry cited a study of 544 male miners and millers exposed for 20 years or longer, in which lung cancer deaths in the least-exposed group were 1.55 times those expected for Canadians matched for age, sex and period. The author disputed the Ontario Royal Commission's conclusion that modern asbestos workers faced no substantial lung cancer hazard. The author concluded that the inquiries had little effect on Canada's asbestos exports.

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: Historical review (published as a special contribution) of the Canadian defence of chrysotile asbestos, covering earlier health reports and two Canadian government inquiries
• Who was studied: No study population. The author reviewed reports on Quebec chrysotile miners and millers from 1912 onward, the McGill University Quebec mining studies, the 1976 Quebec (Beaudry) inquiry, the Ontario Royal Commission, and international actions up to 2007
• Exposure: Chrysotile asbestos mined and milled in Quebec, Canada, and exported
• Main results:
  • In 1912 the Canadian authorities replied to a U.K. inquiry that, on inspection of a large asbestos mine and mill, all the women looked strong and healthy
  • In 1940 the Johns-Manville medical officer studied chest X-rays of 507 current workers employed more than ten years. He found 17 with "early asbestosis", 5 with "moderate asbestosis" and none with "advanced asbestosis". He dismissed the X-ray appearances as irrelevant and concluded there had been no case of asbestosis
  • In 1955 a Thetford Mines medical officer reported that between 1945 and 1953, among some 4,000 Thetford asbestos workers, 128 had asbestosis of various degrees of severity, 121 diagnosed by X-ray and 33 confirmed at autopsy
  • The McGill researchers' final mortality report calculated all-cause mortality for exposures up to 300 mppcf.y at about 7% worse than for the general population of Quebec. The researchers put this down to a possible socio-economic effect
  • The Quebec (Beaudry) committee criticized the McGill study. Of the 11,788 mill and mine workers in its study population, 31.7% had worked less than a year, 64.8% less than ten years, and only 10.2% 30 years or more
  • The Beaudry committee cited Selikoff's Thetford study of 544 male miners and millers employed in 1961 and exposed for 20 years or longer. Lung cancer mortality was 1.55 times that expected for Canadians (matched for age, sex and period) in the least-exposed group, and 4.3 times in the heavier-exposed group
  • The Ontario Royal Commission concluded that no substantial lung cancer mortality hazard existed for modern asbestos workers. The author disputed this conclusion
  • After France banned chrysotile and Canada complained, the World Trade Organization ruled that the French import ban was legal on health grounds
• The authors' conclusion: The author concluded that the Canadian inquiries had little effect on asbestos exports, and that Quebec's chrysotile industry continued to be supported financially by the Canadian government

Topics

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

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

Related studies

• Exposing the "myth" of ABC, "anything but chrysotile": a critique of the Canadian asbestos mining industry and McGill University chrysotile studies — D. Egilman, C. Fehnel, et al. (2003)
• Dust exposure and mortality in chrysotile mining, 1910-75. 1980 — J.C. McDonald, F.D. Liddell, et al. (1993)
• Chrysotile asbestos is the main cause of pleural mesothelioma — A.H. Smith, C.C. Wright (1996)
• Canadian chrysotile report released--at last — T.L. Ogden (2009)
• Canada, chrysotile, and the search for truth — T. Ogden (2008)
• Canada, chrysotile and cancer: Health Canada's Asbestos International Expert Panel report — L.T. Stayner (2008)

Browse more research in International Journal of Occupational and Environmental Health, or return to medical research.