The Geographical Pathology of Mesothelial Tumors

Our plain-English summary of The Geographical Pathology of Mesothelial Tumors, by M.L. Newhouse (1977).

The study

• Author: M.L. Newhouse
• Published: Journal of Occupational Medicine, Volume 19 No7. July 1977
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This 1977 article was a review, not a new study. The author summarized earlier reports on mesothelial tumors in South Africa, the United Kingdom and Europe. The article also included a map of recorded case series in Europe, based on a literature search in summer 1975. In a South African series reported by Webster, 75 of 78 patients with mining exposures had worked in the Cape crocidolite mines and 3 in the Penge amosite mine. A Canadian study by McDonald and colleagues of 11,788 chrysotile mine and mill workers found 5 deaths from pleural mesothelioma. A Finnish study found no deaths from these tumors among over 1,000 men at two anthophylite mine sites. The author cited Timbrell's work showing that fiber length and diameter affect how well fibers penetrate the lung. The author noted that diagnosis is difficult. The author also noted that the number of cases found in an area depends partly on how much research is done there. The author concluded that tumors may be expected where there has been crocidolite exposure, and that amosite and chrysotile are somewhat less pathogenic.

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• Design: Review of published and unpublished reports on the occurrence of mesothelial tumors in different places, with a map of recorded case series in Europe
• Who was studied: Reported cases and series of mesothelial tumors in South Africa, the United Kingdom, Europe and Canada, drawn from other authors' studies; the European map was based on a literature search in the summer of 1975
• Exposure: Four major asbestos types (chrysotile, amosite, anthophylite and crocidolite) in mining, manufacturing, shipyard and environmental settings
• Main results:
  • South Africa (Webster, 1973): of 78 patients with exposures in mining operations, 75 worked in the Cape crocidolite mines and 3 in the Penge amosite mine; the author states the two mines had about equal production until 1960
  • Canada (McDonald et al, 1974): a cohort mortality study of 11,788 chrysotile mine and mill workers born between 1889 and 1920 found only 5 deaths due to pleural mesothelioma
  • Finland (Meurman et al, 1974): no deaths from mesothelial tumors among over 1,000 men employed in two anthophylite mines
  • Timbrell's work: mass for mass, Cape crocidolite produces about thirty times as many fibers as either Transvaal crocidolite or amosite; the author presents this as a possible reason for the preponderance of tumors in the Cape
  • Great Britain: approximately 600 cases were known to have occurred, with about 60 verified new cases reported each year
  • Netherlands (Stumphius): during the 1960s, 25 men died of mesothelial tumors on the Walcheren Islands, and 22 of them had worked at the Naval Dockyards
  • Bohlig's summary of 22 papers from 10 countries covering 812 patients: occupational exposure occurred in 49%, environmental exposure in 19%, and no known asbestos exposure in 32%
  • Grundy and Miller: in 13 children under 18 who died of these tumors, no evidence of asbestos exposure was found, and tissue examination revealed no asbestos bodies or fibers
• The authors' conclusion: The author concluded that tumors may be expected to occur where there has been exposure to crocidolite asbestos, and that amosite and chrysotile asbestos are somewhat less pathogenic. The author named direct occupational exposure as the chief hazard, and added that neighborhood contamination and dust carried home by workers may cause cases.
• Limitations the authors state:
  • Accurate diagnosis of mesothelial tumors is difficult, and they can be confused with secondary tumors
  • The number of tumors identified in an area depends on the vigor of research there, not only on the asbestos industry
  • Missing reports from countries such as Spain, Portugal or Poland reflect lack of research interest, not an absence of tumors
  • Outside mining areas, mixed exposures are the rule, and it is often hard to establish which fiber type a person was exposed to

Topics

Medical terms in this study, explained in our Lexicon: Pathology, Crocidolite, Penge Mine, Amosite, Chrysotile, Pleural Mesothelioma, Fiber Length.

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