Cancer mortality and exposure to crocidolite

Our plain-English summary of Cancer mortality and exposure to crocidolite, by A. Rogers (British Journal of Industrial Medicine, 1990).

The study

• Author: A. Rogers
• Journal: British Journal of Industrial Medicine
• Published: 1990;47(4):286
• Type of article: Letter
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000035).

Summary of the article

This letter responded to papers by de Klerk et al (1988 and 1989) that modelled the relation between asbestos disease risk and airborne exposure at the Wittenoom crocidolite mine and mill. Rogers argued that these models relied heavily on a single, relatively short occupational hygiene survey by Major. When Major retired in 1984 he gave Rogers his long running thermal precipitator slides, and Rogers reassessed some of them with modern light and electron microscopy. He reported that the estimates made about 20 years earlier had underestimated exposure considerably, by up to an order of magnitude. A figure of 27 f/ml could become closer to 200 f/ml under modern resolution criteria and counting rules. The highest recount indicated about 300 f/ml longer than 5 µm and a further 800 f/ml shorter than 5 µm. Samples from the general area outside the plant showed up to 2 f/ml longer than 5 µm. Rogers noted that de Klerk et al had applied estimates for a few occupations in one mill to 87 job classifications in another, dustier mill that closed in 1957. He concluded that their quantitative data could not be supported. In reply, the authors stated that their dose-response estimates relied mainly on internal comparisons, on the ranking of jobs and on duration of exposure. They said the data were the only estimates available, and that Major had helped rank the occupations. They said they would use Rogers' results once these were published and peer reviewed.

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. The author criticised papers by de Klerk et al that relied heavily on a single, relatively short occupational hygiene survey by Major of the Wittenoom crocidolite mine and mill to model asbestos disease risk against airborne exposure. The author had re-examined some of Major's long running thermal precipitator slides with modern light and electron microscopy, with results to be published later. The author reported that the estimates made 20 years earlier underestimated exposure considerably, up to a single order of magnitude. According to the letter, Major was not surprised that his count of 27 f/ml could become closer to 200 f/ml with modern microscopes and counting rules. The highest recount indicated some 300 f/ml longer than 5 micrometres plus some 800 f/ml shorter than 5 micrometres. Areas outside the plant gave up to 2 f/ml longer than 5 micrometres. The author concluded that the quantitative data in de Klerk et al's papers cannot be supported. In a reply, de Klerk et al said their work relied mainly on internal comparisons and job rankings rather than absolute concentrations. They said they were keen to use the author's analyses once published and adequately peer reviewed.

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), with a reply from the criticised authors
• Who was studied: No study population. The letter concerns exposure estimates for occupational groups at the Wittenoom crocidolite mine and mill (Australia), based on Major's thermal precipitator slides from a survey about 20 years earlier (1966).
• Exposure: Airborne crocidolite fibres, as measured on Major's long running thermal precipitator (LRTP) slides, which formed the basis of exposure estimates for a few occupational groups
• Main results:
  • On the author's reassessment of some of the slides, the estimates made 20 years earlier underestimated exposure considerably, up to a single order of magnitude
  • The letter reports that Major was not surprised that his count of 27 f/ml could become closer to 200 f/ml with a microscope meeting modern resolution criteria and current counting rules (the OCR prints 'fpml' for f/ml)
  • The highest light microscopy result on recounting indicated exposures of some 300 f/ml longer than 5 micrometres, plus some 800 f/ml shorter than 5 micrometres
  • Samples from the general area outside the plant gave up to 2 f/ml longer than 5 micrometres
  • The author stated that differences in collection efficiency (LRTP versus modern membrane filter) and between static and personal samples would also increase the estimate of airborne fibres
  • The author noted that de Klerk et al applied Major's estimates for a few occupations in one mill to 87 job classifications in another mill (discontinued in 1957) believed to have been dustier
  • In their reply, de Klerk et al stated that their dose-response estimates rely mainly on internal comparisons within the cohort, on the ranking of jobs, and on duration of exposure rather than absolute dust concentrations
  • In their reply, de Klerk et al said they were keen to use the author's analyses of dust concentrations once these had been published and subjected to adequate peer review
• The authors' conclusion: The author concluded that the quantitative data in de Klerk et al's papers cannot be supported
• Limitations the authors state:
  • The author's reassessment of the slides had not yet been published; the results were to appear in a future publication

Topics

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

Medical terms in this study, explained in our Lexicon: Crocidolite, Wittenoom, Thermal Precipitator, Dose-response relationship.

Related studies

• Radiographic abnormalities and mortality in subjects with exposure to crocidolite — N.H. de Klerk, A.W. Musk, et al. (1993)
• Mortality of workers in a French asbestos cement factory 1940-82 — A.M. Alies-Patin, A.J. Valleron (1985)
• Mortality of two groups of women who manufactured gas masks from chrysotile and crocidolite asbestos: a 40-year follow-up — E.D. Acheson, M.J. Gardner, et al. (1982)
• Dust exposure and mortality in an American factory using chrysotile, amosite, and crocidolite in mainly textile manufacture — A.D. McDonald, J.S. Fry, et al. (1983)
• Mortality of former crocidolite (blue asbestos) miners and millers at Wittenoom — A.W. Musk, N.H. de Klerk, et al. (2008)
• Aerodigestive and gastrointestinal tract cancers and exposure to crocidolite (blue asbestos): incidence and mortality among former crocidolite workers — A. Reid, G. Ambrosini, et al. (2004)

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