Mesothelioma from chrysotile asbestos: update

Our plain-English summary of Mesothelioma from chrysotile asbestos: update, by M.S. Kanarek (Annals of Epidemiology, 2011).

The study

• Author: M.S. Kanarek
• Journal: Annals of Epidemiology
• Published: 2011;21(9):688-97
• Type of article: Review
• Cited by: 66 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: There are different mineral classes of asbestos, including serpentines and amphiboles. Chrysotile is the main type of serpentine and by far the most frequently used type of asbestos (about 95% of world production and use). There has been continuing controversy over the capability of chrysotile asbestos to cause pleural and peritoneal mesothelioma. This review is to help clarify the issue by detailing cases and epidemiology studies worldwide where chrysotile is the exclusive or overwhelming fiber exposure.

Methods: A worldwide literature review was conducted of asbestos and associated mesothelioma including case series, case-control and cohort epidemiology studies searching for well documented chrysotile asbestos associated mesothelioma cases.

Results: Chrysotile asbestos exposures have occurred in many countries around the world from mining, manufacturing and community exposures. There have been many documented cases of mesothelioma from those exposures.

Conclusions: Chrysotile asbestos, along with all other types of asbestos, has caused mesothelioma and a world-wide ban of all asbestos is warranted to stop an epidemic of mesothelioma.

Copyright © 2011 Elsevier Inc. All rights reserved.

In plain English

This article was a single-author review and commentary, not a new study. The author searched worldwide literature for case reports, case series, case-control and cohort studies in which chrysotile was the only or overwhelming asbestos exposure. The studies reviewed came from North America, Europe, Africa, Asia, Australia and New Caledonia. A North Carolina asbestos textile study found eight mesotheliomas overall; after separate coding of mesothelioma began in 1999, it found 4 deaths against 0.37 expected, a standardized mortality ratio of about 11. A 2009 study of Balangero, Italy, chrysotile miners found four pleural mesotheliomas against 0.9 expected. A Mexican case-control study found an odds ratio of 3.7 (95% CI 1.3 to 10.4) for occupational asbestos exposure. The author acknowledged that chrysotile may be less potent than some types, such as South African crocidolite, and that potency disputes will not be easily resolved. The author concluded that chrysotile, along with all other types of asbestos, has caused mesothelioma and that a worldwide ban of all asbestos is warranted. The author also stated that published studies had most certainly missed many cases.

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: Literature review and commentary (not an original study)
• Who was studied: Published case reports, case series, case-control studies and cohort studies from around the world (United States, Canada, Mexico, Europe, Egypt, Zimbabwe, Australia, China, New Caledonia) in which asbestos exposure appeared to be overwhelmingly chrysotile
• Exposure: Chrysotile asbestos as the exclusive or overwhelming fiber exposure, from mining, manufacturing (textiles, friction products, asbestos-cement, plastics), brake repair, and community or naturally occurring serpentine exposure
• Main results:
  • Reviewed study (Loomis et al., North Carolina asbestos textile plants, cohort of 5770 workers): 8 mesotheliomas in total (4 pleural, 4 peritoneal). After mesothelioma began to be coded separately in 1999, 4 deaths were observed against 0.37 expected, a standardized mortality ratio of approximately 11.
  • Reviewed study (Pira et al. 2009, Balangero chrysotile mine, Italy): four pleural mesotheliomas against 0.9 expected (SMR 4.67; 95% CI 1.27 to 11.96). The same study found 5 pleural and peritoneal mesotheliomas against 1.6 expected (SMR 3.16; 95% CI 1.02 to 7.36).
  • Reviewed study (Aguilar-Madrid et al., Mexico, 119 pleural mesothelioma cases and 353 controls; asbestos used in Mexico described as overwhelmingly Canadian chrysotile): the odds ratio for occupational asbestos exposure was 3.7 (95% CI 1.3 to 10.4) for the whole group. It was 14.3 (95% CI 8 to 26) for the 96 cases and 111 controls with the most certain data.
  • Reviewed report (Sturm et al., former East Germany): of 812 mesothelioma cases investigated, detailed information on asbestos grades was available for 481. Sole exposure to chrysotile was determined to be the cause of disease in 67 cases.
  • Reviewed study (Rogers et al., Australian Mesothelioma Surveillance Program, lung fiber analysis in 221 cases): in a subgroup of 25 cases (23 pleural, 2 peritoneal), only chrysotile was found in the lungs. Of these 25, 2 had a definite history of chrysotile-only exposure, 11 had mixed exposure, 10 had no documented asbestos exposure and 2 had no available history. A statistically significant trend (p less than .005) of rising relative risk with rising chrysotile fiber content was reported.
  • Reviewed study (McDonald et al., cohort of 9780 Quebec chrysotile miners and millers): 33 mesotheliomas were observed. The original authors attributed the cases to tremolite contamination. The review's author argued that the distinction is irrelevant because Thetford chrysotile contains roughly 1% tremolite.
  • Reviewed study (Baumann et al., New Caledonia, 109 mesothelioma cases): the odds ratio for the serpentine (antigorite) area was 20.667 (95% CI 4.028 to 106.03). For the tremolite-actinolite area it was 1.714 (95% CI 0.664 to 4.423).
• The authors' conclusion: The author concluded that chrysotile asbestos, along with all other types of asbestos, has caused mesothelioma, and that a worldwide ban of all asbestos is warranted. The author also stated that chrysotile may be less potent than certain types, such as South African crocidolite.
• Limitations the authors state:
  • The author stated that the published studies most certainly missed many chrysotile-related mesothelioma cases. The reasons given were difficult pathologic diagnosis, difficulty documenting past work exposures, exposed workers who left the industry without being studied, and environmental exposure of non-workers.
  • The author acknowledged legitimate scientific controversy over the relative potency of different asbestos types and said this will not be easily resolved.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Chrysotile, Serpentine Group, Amphibole Group, Peritoneal Mesothelioma, Epidemiology, Asbestos Exposure.

Related studies

• Different cellular responses evoked by natural and stoichiometric synthetic chrysotile asbestos — E. Gazzano, E. Foresti, et al. (2005)
• Environmental contamination of chrysotile asbestos and its toxic effects on antioxidative system of Lemna gibba — A.K. Trivedi, I. Ahmad, et al. (2007)
• Long-term instillation to four natural representative chrysotile of China induce the inactivation of P53 and P16 and the activation of C-JUN and C-FOS in the lung tissues of Wistar rats — Y. Luo, J. Deng, et al. (2020)
• Mesothelioma in a worker who spun chrysotile asbestos at home during childhood — E. Yano, Z.M. Wang, et al. (2009)
• Germline mutations in DNA repair genes predispose asbestos-exposed patients to malignant pleural mesothelioma — M. Betti, E. Casalone, et al. (2017)
• Environmental health of children — A.M. Dunn, C. Burns, et al. (2003)

Browse more research in Annals of Epidemiology, or return to medical research.