Chrysotile asbestos: effects of human exposure

Our plain-English summary of Chrysotile asbestos: effects of human exposure, by A.N. Rohl, A.M. Langer, I.J. Selikoff (Science, 1977).

The study

• Authors: A.N. Rohl, A.M. Langer, I.J. Selikoff
• Journal: Science
• Published: 1977;198(4323):1202
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

This letter replied to a letter by John T. Hack about environmental asbestos pollution in Rockville, Maryland. The authors agreed that the pollution was primarily chrysotile from the Rockville quarry. They disputed Hack's suggestion that studies of chrysotile miners and millers in Quebec, Canada, exonerated the quarry's crushed rock as a carcinogen, and his claim that these workers' general health was comparable to that of Quebec Province as a whole. They noted that latent periods for asbestos-related malignancy appear to extend from 20 to 40 years or more from the onset of exposure, and that exposure intensity influences both disease risk and latency. They cited McDonald and Becklake's own list of asbestos-associated diseases in Canada. They argued that the Quebec studies grouped about 4000 workers by total exposure in 'MPCF-years' rather than by years since onset of exposure, which mixed workers with short and long latency periods. Even so, workers with 400 to 800 MPCF-years had a 2.1 elevated risk of respiratory cancer, and those above 800 MPCF-years had a 3.6 times elevated risk. The authors considered these figures conservative. They also cited the Beaudry Commission's findings of poor worker education, dangerous methods, negligent inspection and a lack of medical surveillance in the Quebec industry, as well as an IARC conclusion that reassurance was unwarranted. They concluded that chrysotile mining and milling had been established as hazardous.

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 letter to the editor of Science, not a research study. It replied to an earlier letter by John T. Hack about asbestos pollution in Rockville, Maryland. The authors agreed that this pollution came mainly from chrysotile in the Rockville quarry. They disagreed with Hack's suggestion that studies of Quebec chrysotile miners and millers cleared the quarry's crushed rock as a cause of cancer. They argued that those Quebec studies grouped 4000 workers by total dust exposure (million particles per cubic foot multiplied by years) rather than by years since first exposure. They said this mattered because asbestos cancers appear about 20 to 40 years or more after exposure begins. Even so, they noted, one Quebec study reported a 2.1 elevated risk of respiratory cancer for workers with 400 to 800 MPCF-years and a 3.6 times elevated risk above 800 MPCF-years. The authors considered these figures conservative. They also cited findings of the Beaudry Commission in Thetford, Quebec, and of a World Health Organization agency. The authors concluded that chrysotile mining and milling had been established as hazardous.

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 replying to an earlier letter; no new data were collected
• Who was studied: No population was studied by the authors. The letter discusses published studies of chrysotile miners and millers in Quebec, Canada, in which 4000 individuals with mortality data were grouped by total exposure. It also discusses environmental pollution in Rockville, Maryland.
• Exposure: Chrysotile asbestos. This covers environmental pollution from the Rockville, Maryland quarry and dust in Quebec chrysotile mining and milling. In the Quebec studies, dust exposure was measured as million particles per cubic foot (MPCF) multiplied by years exposed.
• Main results:
  • The authors argued that Hack was incorrect in suggesting that the Quebec studies exonerate the crushed rock from the Rockville quarry as a carcinogen.
  • The authors criticized the Quebec study design. Workers were grouped by total exposure in MPCF-years, not by years from the onset of exposure.
  • Citing earlier work, the authors stated that latent periods for asbestos-related malignant disease appear to extend from 20 to 40 years or more from the onset of exposure.
  • Citing the 1976 McDonald and Becklake study (not the authors' own data), Quebec workers with 400 to 800 MPCF-years exposure had a 2.1 elevated risk of developing respiratory cancer.
  • Citing the same study, Quebec workers with greater than 800 MPCF-years exposure had a 3.6 times elevated risk of respiratory cancer.
  • The authors considered these risks conservative, because each exposure group may include individuals who had not completed the long latency period.
  • The authors reported the findings of the Beaudry Commission's study of chrysotile miners in Thetford, Quebec. The commission found that the industry failed to educate workers about the dangers and used outdated, dangerous methods. It also found that government inspectors had been negligent, that medical surveillance and protection were lacking, and that no proper controls had been installed.
  • The authors quoted an agency of the World Health Organization. It concluded that uncontrolled exposure to chrysotile, as to other types of asbestos, has the potential for serious human disease.
• The authors' conclusion: The authors concluded that chrysotile mining and milling had been established as hazardous.

Topics

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

Related studies

• Cytotoxicity of a short-fiber chrysotile asbestos for human alveolar macrophages: preliminary observations — H. Yeager, D.A. Russo, et al. (1983)
• Variation of properties of chrysotile asbestos subjected to milling — A.M. Langer, M.S. Wolff, et al. (1978)
• Leaching of chrysotile asbestos in human lungs. Correlation with in vitro studies using rabbit alveolar macrophages — M.C. Jaurand, J. Bignon, et al. (1977)
• Continuous exposure to chrysotile asbestos can cause transformation of human mesothelial cells via HMGB1 and TNF-α signaling — F. Qi, G. Okimoto, et al. (2013)
• The asbestos fibre burden in human lungs: new insights into the chrysotile debate — I.S. Feder, I. Tischoff, et al. (2017)
• Chromosomal aberrations induced by chrysotile and crocidolite in human lymphocytes in vitro — F. Valerio, M. de Ferrari, et al. (1983)

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