Are all mesotheliomas due to asbestos?

Our plain-English summary of Are all mesotheliomas due to asbestos?, by D. Davies (British Medical Journal, 1984).

The study

• Author: D. Davies
• Journal: British Medical Journal
• Published: 1984;289(6453):1164-5
• Type of article: Editorial
• Cited by: 5 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. 001652).

Summary of the article

This editorial asked whether all mesotheliomas are caused by asbestos. The author noted that mesothelioma is closely related to asbestos exposure, which is sometimes light and transient. The author cited a Liverpool study of 100 patients with pleural mesothelioma: exposure was established in 88, and all but one of these had over 20 000 asbestos fibres per gram of dried lung by light microscopy. No exposure was discovered in seven; six of these had counts below 20 000, and two had no fibres seen. Among controls, 29% had over 20 000 fibres per gram. Electron microscopy would probably find more fibres, but mainly chrysotile rather than the amphiboles that are the main determinants of mesothelioma. The author cited reports that some mesotheliomas were diagnosed before asbestos became common, that unexposed patients develop them at an earlier age, and that their parents have a high incidence of cancer. From latency data on gas mask workers, asbestos factory workers (mean latent period to death 32 years), South Africa and the erionite area of Turkey, the author concluded that most, if not all, fibre-induced mesotheliomas have a latent period of at least 12 years. Because sporadic cases occur in unexposed children under 12, the author considered it reasonable to postulate that some adult cases are not caused by asbestos, and stressed the medicolegal importance of the latent period.

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 was a short editorial, not an original study, in which the author discussed published reports to ask whether every mesothelioma is caused by asbestos. The author cited a Liverpool study in which asbestos exposure was established in 88 of 100 patients with pleural mesothelioma. In 7 patients no exposure was found, and 6 of these had lung counts below 20 000 fibres per gram of dried lung. The author noted that most lungs contain some asbestos. Fibres missed by light microscopy would mainly be chrysotile, not the amphibole fibres the author called the main determinants of mesothelioma. Other cited reports covered long latency, mesotheliomas diagnosed before asbestos was common, and cases in unexposed children under 12. The author concluded that most, if not all, fibre-induced mesotheliomas have a latent period of at least 12 years and usually much longer. The author also concluded that it is reasonable to postulate that some adult cases are not caused by asbestos. The author called the latent period medicolegally important when a tumour appears soon after 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: editorial (opinion piece) discussing published studies; no original data
• Who was studied: No population of its own. The author drew on published reports, including 100 patients with pleural mesothelioma in Liverpool, lung specimens from East Anglia, gas mask workers, asbestos factory workers, people in South Africa and in an area of Turkey, and unexposed children
• Exposure: Asbestos in general, measured as coated and uncoated fibres per gram of dried lung. The author distinguished chrysotile from amphibole fibres, and also mentioned crocidolite pollution in South Africa and the non-asbestos mineral erionite in Turkey
• Main results:
  • Cited Liverpool study, pleural mesothelioma patients: in all but one of the 88 with established exposure, light microscopy showed over 20 000 coated and uncoated asbestos fibres per gram of dried lung. In 7 no exposure was discovered; 6 of these had counts below 20 000, and among those 6, 2 had no fibres seen and 4 had several thousand per gram
  • Cited Liverpool study, controls: 29% of specimens had over 20 000 fibres per gram, and in only seven were none seen
  • Cited East Anglia report: 4% of specimens taken at surgery and 30% of those taken at necropsy did not show fibres
  • Cited report on gas mask workers: exposure was between 1939 and 1944, and the first tumour appeared in 1963
  • Cited report on asbestos factory workers: the mean latent period to death was 32 years, and in only two of 188 was it less than 18 years (both 14 years)
  • Cited report from the area of Turkey where erionite-related mesotheliomas are common: tumours did not occur in persons under 20, despite exposure from early childhood
  • The author cited mesotheliomas diagnosed before asbestos became a common material, which the author said suggested they were not caused by asbestos
  • The author cited reports that mesothelioma in unexposed people occurs at an earlier age than asbestos-related tumours, and that sporadic cases occur in unexposed children below the age of 12
  • The author concluded that most, if not all, fibre-induced mesotheliomas have a latent period of at least 12 years and usually much longer
  • The author stated that the latent period is of medicolegal importance when a mesothelioma develops soon after asbestos exposure, particularly light exposure
• The authors' conclusion: The author concluded that cases in unexposed children are most probably not caused by environmental asbestos, so it is reasonable to postulate that some cases in adults are also not caused by asbestos
• Limitations the authors state:
  • The author noted that fibre-count figures are influenced by the technique used
  • The author noted that light microscopy greatly underestimates fibre numbers, and that electron microscopy would probably find considerable numbers in many cases that appeared negative

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Asbestos Exposure, Pleural Mesothelioma, Chrysotile, Amphibole Group, Latency, erionite.

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• Cancer survival and prevalence in Australia: period estimates from 1982 to 2010 — Australian Institute of Health and Welfare (2013)
• Mesothelioma risk after 40 years since first exposure to asbestos: a pooled analysis — A. Reid, N.H. de Klerk, et al. (2014)
• Well-differentiated papillary mesothelioma with invasive foci — A. Churg, T. Allen, et al. (2014)
• Mesothelioma in household members of asbestos-exposed workers: 32 United States cases since 1990 — A. Miller (2005)
• Mortality of workers in a French asbestos cement factory 1940-82 — A.M. Alies-Patin, A.J. Valleron (1985)

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