Mineral Fibre Content Of Lung In Mesothelial Tumours: Preliminary Report

Our plain-English summary of Mineral Fibre Content Of Lung In Mesothelial Tumours: Preliminary Report, by A.D. Mcdonald (1980).

The study

• Author: A.D. Mcdonald
• Published: Biological Effects Of Mineral Fibres (J.C. Wagner, Editor), Lyon: Iarc Scientific Publications, Volume 30, Pp. 681-685 (1980)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library, J-M no. 000833. The article is still under copyright, so we describe it here rather than post it.

In plain English

This preliminary report compared asbestos fibres in the lungs of people who died of malignant mesothelial tumours in North America in 1972 with those of matched controls. Each case diagnosed at autopsy was matched by sex and age to a control with lung metastases from a cancer other than lung cancer. Tissue was obtained for 100 pairs. This report covered the first 37 pairs (32 male, 5 female), analysed blind by electron microscopy. Chrysotile fibres were far more common than any amphibole, and their distribution was remarkably similar in cases and controls. Male cases had a clear excess of amosite fibres compared with controls. Crocidolite and tremolite showed a marginal excess in cases, but the numbers were too small to interpret. Anthophyllite showed no difference. Among male cases, amosite counts of one million or more fibres per gram of dried lung tissue were found in three of four insulators, but only one control reached that level. The author concluded that the data supported an earlier suggestion that amosite, introduced especially for naval purposes, may have caused mesotheliomas in US insulators.

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: Matched case-control study (preliminary report) with blind electron-microscope analysis of lung tissue
• Who was studied: Of 274 fatal malignant mesothelial tumours ascertained in North America in 1972, the 172 cases diagnosed at autopsy were each matched for sex and age to a control with pulmonary metastases from a primary tumour other than lung cancer. Lung tissue was obtained for 100 case-control pairs (77 male, 23 female). This report covers the first 37 pairs (32 male, 5 female).
• Exposure: Numbers of fibres per gram of dried lung tissue of chrysotile and four amphiboles (crocidolite, amosite, anthophyllite and tremolite), measured by electron microscope and X-ray energy dispersive analyser
• Main results:
  • In both cases and controls, chrysotile fibres were far more prevalent than any of the amphiboles.
  • The distribution of chrysotile fibres was remarkably similar in male and female cases and controls.
  • There was a clear excess of amosite fibres in male cases compared with controls.
  • Crocidolite and tremolite showed a marginal excess in cases, but the numbers were too small to interpret. Anthophyllite showed no difference between cases and controls.
  • The four cases with one million or more crocidolite fibres (per gram of dried lung tissue) had higher fibre levels of amosite than of crocidolite.
  • Among the 32 male cases, an amosite count of one million or more fibres per gram of dried lung tissue was found in 3 of the 4 insulators, 2 of the 2 asbestos factory workers, 3 of the 10 men in heating trades, and 3 of the 4 shipyard employees (excluding those in insulation and heating trades).
  • Only one control had an amosite count of this magnitude: a man who had worked in gold and silver mines.
• The authors' conclusion: The author stated that the data support the author's earlier suggestion that the introduction of amosite, especially for naval purposes, may have been responsible for mesotheliomas in insulators in the US. The author also wrote that the data supported earlier epidemiological evidence about the risk of mesothelioma after chrysotile exposure, but the line describing that risk is cut off in the scan.
• Limitations the authors state:
  • The results are preliminary and cover only the first 37 of 100 case-control pairs. Analyses of all pairs, and of other mineral fibres, were to be reported later.
  • For crocidolite and tremolite, the numbers were too small to interpret.

Topics

Medical terms in this study, explained in our Lexicon: Autopsy, Lung Cancer, Chrysotile, Amphibole Group, Amosite, Crocidolite, Tremolite, Anthophyllite.

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