Scientific objectivity and the chrysotile controversy

Our plain-English summary of Scientific objectivity and the chrysotile controversy, by B.I. Castleman (Occupational and Environmental Medicine, 1994).

The study

• Author: B.I. Castleman
• Journal: Occupational and Environmental Medicine
• Published: 1994;51(6):431
• Type of article: Comment, Letter
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

In plain English

This was a letter to the editor, not a research study, and it reported no new data. The author responded to a 1993 letter on chrysotile asbestos by Jacques Dunnigan. The author noted that Dunnigan listed only the University of Sherbrooke as an affiliation but was longtime Director for Health and Environment of Canada's Asbestos Institute, which asbestos mining companies and government jointly supported. The author disputed an Institute claim that Selikoff's insulation workers were exposed mostly to amosite. The author stated that amosite was not used in significant quantities in US insulation until the 1940s. The author also cited Nicholson and Landrigan as finding, among 56 mesothelioma deaths in that cohort through 1992, no sudden steep rise starting in the 1960s of the kind expected if amosite, not chrysotile, were the main cause. The author also cited industry studies reporting fibre counts of 30-60 f/ml from hand sawing asbestos-containing panels. The author criticized a World Health Organisation (IPCS) group preparing a chrysotile report as loaded in favour of asbestos interests. The author called it a hopeful sign that independent scientists and US institutions were addressing concerns about the objectivity of the IPCS asbestos document.

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); opinion piece with no original data
• Exposure: No exposure was measured. The letter discusses chrysotile asbestos, and whether amosite rather than chrysotile explains disease in US insulation workers.
• Main results:
  • The author stated that Dunnigan's 1993 letter summarized a then-unpublished paper which, according to Dunnigan, found no occupational risk of lung cancer in workers exposed to 45 f/ml for 20 years.
  • The author pointed out that Dunnigan listed only the University of Sherbrooke as an affiliation. The author described the Asbestos Institute's stated purpose as defending and promoting the safe use of asbestos.
  • The author disputed the Asbestos Institute President's claim that Selikoff's insulation workers were exposed mostly to amosite. The author stated that amosite only began to be used in significant quantities in US insulation in the 1940s.
  • The author cited Nicholson and Landrigan's work on the 56 mesothelioma deaths in the original Selikoff cohort through 1992. According to the author, that work found no sudden, steeply rising mesothelioma incidence starting in the 1960s, which would be expected if amosite (and not chrysotile) were the main cause.
  • The author disputed the Institute's claim that hand tools at construction sites mainly produce non-respirable dust. The author cited industry studies showing that hand sawing asbestos-containing panels generates fibre counts of 30-60 f/ml.
  • The author stated that the IPCS group preparing a report on chrysotile was so loaded in favour of asbestos interests that it had been denounced by the National Institute for Occupational Safety and Health, the Collegium Ramazzini and Dr Philip Landrigan.
• The authors' conclusion: The author found it remarkable that debate over whether chrysotile causes cancer was still going on. The author considered it a hopeful sign that independent scientists and participating US institutions were taking unprecedented steps over concerns about the scientific objectivity of the IPCS criteria document on asbestos.

Topics

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

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

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• The So-called Short-Fiber Controversy: Literature Review and Critical Analysis — V.L. Roggli (2015)
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