Amphiboles and chrysotile asbestos exposure

Our plain-English summary of Amphiboles and chrysotile asbestos exposure, by V.L. Roggli, P.C. Pratt (American Journal of Industrial Medicine, 1988).

The study

• Authors: V.L. Roggli, P.C. Pratt
• Journal: American Journal of Industrial Medicine
• Published: 1988;14(2):245-6
• Type of article: Letter
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000265).

Summary of the article

This letter to the editor responded to an article by Dunnigan (1988), which argued that when patients with mesothelioma have been exposed to both amphiboles and chrysotile asbestos, the amphibole exposure is responsible for the tumor. The authors, pathologists at Duke University Medical Center, agreed that amphiboles are more potent than chrysotile in producing mesothelioma. They noted that long, thin fibers are most likely to cause it and that fiber durability and retention are probably also important. They then raised several points.

First, there are case reports, not mentioned by Dunnigan, of mesothelioma in patients allegedly exposed only to chrysotile-containing products. Second, the few cases in chrysotile cohort studies should be weighed against a background rate of one or two cases per million population per year. Third, because of the long latency, cohorts need 30 or 40 years of follow-up.

On tissue fiber analysis, they cited rat inhalation studies by Wagner et al. (1974). In those studies amphibole fibers accumulated in proportion to exposure duration, while chrysotile burden plateaued after a couple of months. This would raise the amphibole-to-chrysotile ratio as cumulative exposure increased. Yet in the same studies chrysotile was as efficient as amphiboles in producing asbestosis, and Canadian chrysotile produced as many mesotheliomas as crocidolite. In humans, asbestosis occurs with chrysotile-only exposure despite low lung retention.

The authors concluded that one cannot be as complacent as Dunnigan suggested that chrysotile plays no significant role in such patients.

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 letter to the editor reported no new data. The authors responded to an article by Dunnigan (1988). That article argued that when mesothelioma patients had been exposed to both amphiboles and chrysotile asbestos, the amphibole exposure was responsible for the tumor. The authors agreed that amphiboles are more potent than chrysotile in producing mesothelioma, but raised counterpoints from other published work. They pointed to case reports of mesothelioma in patients allegedly exposed only to chrysotile-containing products. They noted a background rate of one or two mesothelioma cases per million people per year, and said worker cohorts need 30 or 40 years of follow-up. Citing a 1974 rat study by Wagner and colleagues, they noted that amphibole fibers built up in the lungs while chrysotile levels leveled off after a couple of months. Yet in that study chrysotile caused asbestosis as efficiently as amphiboles, and rats breathing Canadian chrysotile dust developed as many mesotheliomas as rats breathing crocidolite. The authors concluded that one cannot be as complacent as Dunnigan suggested that chrysotile plays no significant role in mesothelioma after mixed 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 (commentary responding to another article; no original data)
• Exposure: Mixed exposure to amphibole and chrysotile asbestos in people with mesothelioma (discussed, not studied)
• Main results:
  • The letter responded to Dunnigan's (1988) argument that, in mesothelioma patients exposed to both amphiboles and chrysotile, the amphibole exposure produced the tumor.
  • The authors agreed that amphiboles are more potent than chrysotile in producing mesothelioma.
  • The authors cited case reports (Castleman, 1984) of mesothelioma in patients allegedly exposed only to chrysotile-containing products.
  • The authors said the few mesothelioma cases in chrysotile cohorts should be weighed against a background rate of one or two cases per million population per year (citing McDonald and McDonald, 1980).
  • Because of mesothelioma's long latency, the authors said cohorts need 30 or 40 years of follow-up (citing Enterline et al., 1987).
  • In rat inhalation studies by Wagner et al. (1974), cited by the authors, amphibole fibers accumulated in the lungs in proportion to duration of exposure.
  • In the same rat studies, chrysotile lung fiber burden reached a plateau after a couple of months.
  • In the Wagner et al. (1974) rat studies, chrysotile was as efficient as amphiboles in producing asbestosis.
  • In the Wagner et al. (1974) rat studies, as many mesotheliomas occurred in rats breathing Canadian chrysotile dust as in rats breathing crocidolite.
  • The authors stated that in humans asbestosis occurs in people exposed only to chrysotile dust or chrysotile-containing products.
• The authors' conclusion: The authors concluded that one cannot be as complacent as Dunnigan suggested that chrysotile plays no significant role in mesothelioma in patients exposed to both amphiboles and chrysotile.

Topics

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

Medical terms in this study, explained in our Lexicon: Amphibole Group, Chrysotile, Asbestos Exposure, Mesothelioma, Fiber Durability, Background Rate, Latency, Cumulative Exposure.

Related studies

• Analysis of amphibole asbestos in chrysotile and other minerals — J. Addison, L.S. Davies (1990)
• Biological in vitro and in vivo responses of chrysotile versus amphiboles — J. Bignon, M.C. Jaurand (1983)
• Chrysotile, tremolite, and malignant mesothelioma in man — A. Churg (1988)
• Tremolite, other amphiboles, and mesothelioma — J.C. McDonald (1988)
• Asbestos fiber concentrations in the lungs of brake repair workers: commercial amphiboles levels are predictive of chrysotile levels — G.M. Marsh, A.O. Youk, et al. (2011)
• Environmental pleural plaques in residents of a Quebec chrysotile mining town — A. Churg, L. DePaoli (1988)

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