A report on the health of asbestos, Quebec miners 1940

Our plain-English summary of A report on the health of asbestos, Quebec miners 1940, by M. Greenberg (American Journal of Industrial Medicine, 2005).

The study

• Author: M. Greenberg
• Journal: American Journal of Industrial Medicine
• Published: 2005;48(3):230-7
• Type of article: Historical article
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Twenty years after the start-up of the Canadian asbestos industry, reports began to appear of respiratory disease and deaths in asbestos workers in England and in France. An inquiry from the UK in 1912 as to the health of Quebec miners was met by a denial of ill-health, but the loading of the premiums of asbestos workers in the 1930s indicated that, despite further reassuring health studies on Quebec miners, actuaries had data that gave cause for serious concern.

Methods: A report made to the Canadian asbestos industry by a company doctor in 1940, reviewing the literature and presenting his health findings on some 500 employees, was studied in the context of the published information available at the time, and of unpublished contemporaneous material subsequently obtained by legal discovery.

Results: The physician denied that the health and longevity of Quebec's miners and millers were adversely affected, and was dismissive of earlier reports of there being serious health risks associated with working with asbestos.

Conclusions: The methodology employed in his health study was defective and his denial of the literature uninformed. The study was widely circulated, and while it may have boosted Canadian industry morale, it met with a sceptical response from British industry. In denying that conditions in Quebec's asbestos mines and mills disabled and killed workers, the author allied himself to fellow professionals loyal to Government and to industry.

In plain English

This historical article examined a 1940 typescript report on asbestosis by Dr. Stevenson, the company doctor at the Johns-Manville plant at Asbestos, Quebec. The author read it against the medical literature of the time and against company documents later obtained through legal discovery. The 1940 report covered 507 men who had worked more than 10 years. On stereoscopic chest X-rays, Stevenson counted 17 cases of early and 5 of moderate asbestosis, none advanced: 22 of 507 men, or 4.33%. Judging by clinical findings alone, Stevenson put the share suffering from asbestosis at exactly zero. Stevenson also reported that none of about a dozen deceased long-service workers had died of a lung condition. The author found several of the report's citations of other experts to be inaccurate. Directors of the British company Turner and Newall responded sceptically. A later report by the mines' medical officer, Cartier, described 128 of some 4,000 Thetford workers with asbestosis. The author concluded that Stevenson's study methods were defective and the dismissal of earlier literature uninformed.

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 of a 1940 company doctor's report, assessed against the published literature of the time and against unpublished documents obtained by legal discovery
• Who was studied: The 1940 report covered 507 men on the payroll of the Johns-Manville plant at Asbestos, Quebec, who had worked there more than 10 years
• Exposure: Work in Quebec asbestos (chrysotile) mining and milling at the Johns-Manville plant at Asbestos, Quebec
• Main results:
  • In the 1940 report, based on stereoscopic X-rays only, Stevenson counted 17 cases of early asbestosis, 5 of moderate asbestosis and 0 of advanced asbestosis among the 507 men: 22 cases, or 4.33%
  • Judging by case history and physical examination, the 1940 report put the percentage of these men suffering from asbestosis at exactly zero
  • The 1940 report stated that none of the roughly dozen members of the company's 25-year club who had died had died of a lung affection
  • The author found that several page references the 1940 report gave for other experts' views did not support it, for example a cited page of Gloyne
  • A Turner and Newall director, writing in 1940, doubted Stevenson's experience with post-mortem examinations
  • At a 1940 meeting on proposed Quebec law changes, the mining group was reported to prefer that asbestosis not be included in the occupational disease law, or, if included, that it be listed separately
  • A later report by the mines' medical officer, Cartier (1955), based on data from some 4,000 Thetford asbestos workers between 1945 and 1953, found 128 workers with asbestosis
• The authors' conclusion: The author concluded that the methods of Stevenson's health study were defective and the dismissal of earlier literature uninformed. In the author's view, the report exemplified the work of a physician loyal to Government and to industry.
• Limitations the authors state:
  • The author stated that the photocopy of the 1940 report was not entirely clear, with problems of legibility and with reconciling the stated 17 early asbestosis cases against the sub-totals

Topics

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

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

Related studies

• The 1891-1920 birth cohort of Quebec chrysotile miners and millers: development from 1904 and mortality to 1992 — F.D. Liddell, A.D. McDonald, et al. (1997)
• The 1891-1920 birth cohort of Quebec chrysotile miners and millers: mortality 1976-88 — J.C. McDonald, F.D. Liddell, et al. (1993)
• Long-term mortality experience of chrysotile miners and millers in Thetford Mines, Quebec — W.J. Nicholson, I.J. Selikoff, et al. (1979)
• Clinical measurement in Quebec chrysotile miners: use for future protection of workers — M.R. Becklake (1979)
• The health of chrysotile asbestos mine and mill workers of Quebec — J.C. McDonald, M.R. Becklake, et al. (1974)
• Exploratory sampling of asbestos in residences near Thetford Mines: the public health threat in Quebec — M. Marier, W. Charney, et al. (2007)

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