Nonoccupational exposure to chrysotile asbestos and the risk of lung cancer

Our plain-English summary of Nonoccupational exposure to chrysotile asbestos and the risk of lung cancer, by A. Churg (The New England Journal of Medicine, 1998).

The study

• Author: A. Churg
• Journal: The New England Journal of Medicine
• Published: 1998;339(14):999; author reply 1001-2
• Type of article: Comment, Letter
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

In a letter to the editor, Churg responded to a study by Camus et al. of lung cancer risk among women with nonoccupational exposure to chrysotile asbestos in Quebec's mining regions. He argued that the study's standardized mortality ratios for mesothelioma and asbestosis may have been seriously confounded by hidden exposure to the amphibole asbestos types amosite and crocidolite. His laboratory had analyzed many lung specimens obtained at autopsy from chrysotile workers in the Thetford Mines region and from residents who never worked in the mines or mills. As a rule, only chrysotile and tremolite had been found. However, three women from the region who had died of mesothelioma between 1983 and 1988, and who had not worked in the mines or mills, had elevated amosite and crocidolite levels of 100,000, 1,000,000 and 4,300,000 fibers per gram of dry lung. The laboratory's maximal background level was 10,000. These levels were within the range seen in mesothelioma cases among amphibole-exposed workers. The second and third women had levels typical of amphibole-associated asbestosis and had asbestosis at autopsy. Both had worked in an asbestos-bag-repair operation, the probable source of their exposure. The first woman's source was uncertain but was not ambient air. Churg concluded that the cases were probably counted by Camus et al. and that the mesothelioma risk from nonoccupational chrysotile exposure in that population was lower than reported. An editor's note stated that he had served as an expert witness in asbestos litigation. In their reply, Camus and Siemiatycki called his suggestion a possibility to be explored in ongoing research.

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

In this letter to the editor, Churg commented on a Camus et al. study of lung cancer risk from environmental chrysotile exposure. The author argued its mortality ratios for mesothelioma and asbestosis may be seriously confounded by hidden amosite and crocidolite exposure. The author's laboratory examined autopsy lung tissue from three women of Quebec's Thetford Mines region who died of mesothelioma in 1983 to 1988 and never worked in the mines or mills. Their lungs held 100,000, 1,000,000 and 4,300,000 amosite and crocidolite fibers per gram of dry lung. The laboratory's maximal general-population background for amosite plus crocidolite is 10,000 fibers per gram of dry lung. The second and third had asbestosis at autopsy. Both had worked repairing asbestos bags, which the author called the probable source of their amphibole exposure. The first woman's source was uncertain but, the author stated, clearly not ambient air. The author wrote that these findings suggest the Camus population's mesothelioma risk from nonoccupational chrysotile exposure is lower than reported. Camus and Siemiatycki replied that they would explore, in ongoing research, whether the pleural cancer and asbestosis cases came from occupational rather than nonoccupational exposure.

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 commenting on a published study, reporting lung fiber analyses from three autopsy cases
• Who was studied: Three women from the Thetford Mines region of Quebec, Canada, who died of mesothelioma between 1983 and 1988 and had not worked in the mines or mills
• Exposure: Amosite and crocidolite measured in lung tissue (100,000, 1,000,000 and 4,300,000 fibers per gram of dry lung), in women living in a chrysotile-mining region. Two of them had worked in an asbestos-bag repair operation.
• Main results:
  • In the author's laboratory, the maximal background level of amosite plus crocidolite in the general population is 10,000 fibers per gram of dry lung. The levels in the three women were above this.
  • The second and third women had asbestosis at autopsy
  • The second and third women worked in the asbestos-bag repair operation mentioned by Camus et al. The author considered this the probable source of their amphibole exposure.
  • The source of exposure for the first woman was uncertain, but the author stated it was clearly not ambient air
  • The author stated that these cases appear to have been included in the mesothelioma (and probably asbestosis) counts of Camus et al. According to the author, two, and probably all three, were not nonoccupational.
  • In their reply, Camus and Siemiatycki said they would explore in their ongoing research the suggestion that the pleural cancer and asbestosis cases came from occupational rather than nonoccupational exposure
• The authors' conclusion: The author considered it likely that amosite and crocidolite exposure caused these three tumors. The author wrote that the findings suggest the risk of mesothelioma from nonoccupational chrysotile exposure in the population studied by Camus et al. is lower than they reported, and that there may or may not be an increased risk of asbestosis.
• Limitations the authors state:
  • The source of exposure for the first patient is uncertain
  • The author states only that these cases appear to have been counted in the Camus et al. study; this was not confirmed

Topics

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

Medical terms in this study, explained in our Lexicon: Chrysotile, Lung Cancer, standardized mortality ratio (SMR), Mesothelioma, Amphibole Asbestos, Amosite, Crocidolite, Autopsy.

Related studies

• Lung asbestos content in long-term residents of a chrysotile mining town — A. Churg (1986)
• Nonoccupational exposure to chrysotile asbestos and the risk of lung cancer — M. Camus, J. Siemiatycki, et al. (1998)
• Respiratory cancer in chrysotile textile and mining industries: exposure inferences from lung analysis — P. Sebastien, J.C. McDonald, et al. (1989)
• Fiber burden and patterns of asbestos-related disease in chrysotile miners and millers — A. Churg, J.L. Wright, et al. (1993)
• Environmental pleural plaques in residents of a Quebec chrysotile mining town — A. Churg, L. DePaoli (1988)
• Lung asbestos content in chrysotile workers with mesothelioma — A. Churg, B. Wiggs, et al. (1984)

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