Physics and Chemistry of Asbestos Dust

Our plain-English summary of Physics and Chemistry of Asbestos Dust, by L. Le Bouffant (1980).

The study

• Author: L. Le Bouffant
• Published: Biological Effects of Mineral Fibres Volume 2, Ed.: J.C. Wagner, International Agency for Research on Cancer Scientific Publications No.30, Lyon. p15-33 (1980)
• Type of article: Conference paper
• 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 article was a review presented at an International Agency for Research on Cancer symposium. The author summarised the symposium papers on the physics and chemistry of asbestos dust and added findings from the author's own laboratory. The reviewed papers covered the UICC reference samples, airborne fibre sizes, automated counting methods, asbestos-cement dust and fibres in human lungs. In the author's own work on about 500 human lung specimens, many kinds of fibre were found. Mullite fibres appeared in more than 50% of the lungs examined. Across several hundred lungs, the ratio of electron microscope counts to light microscope counts varied between 10 and 10,000 times. Lung contents did not always match known exposure: a spinning-mill worker who mostly handled chrysotile had only traces of chrysotile but many amosite fibres. In six cases with low or moderate exposure, no chrysotile was detected in the lungs, while the median concentration in the pleura was 3000 fibres per gram of dry tissue. The author concluded that chrysotile is eliminated more rapidly than the amphiboles and migrates more easily into the pleura.

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 (rapporteur's summary) of papers presented at a symposium, combined with the author's own laboratory studies of lung and pleural specimens and a rat experiment
• Who was studied: Symposium papers on asbestos dust. In the author's own work: about 500 human lung specimens; 17 cases with both lung and parietal pleura samples; rats given chrysotile in peritoneal microchambers
• Exposure: Asbestos fibres including amosite, anthophyllite, crocidolite, chrysotile (UICC Rhodesian A and Canadian B samples) and tremolite, as well as asbestos-cement dust and other mineral fibres found in lungs
• Main results:
  • In the author's lung studies, mullite fibres were found in more than 50% of lungs examined
  • In counts made by the author's group on several hundred lungs, the ratio of electron microscopy to light microscopy fibre counts varied between 10 and 10,000 times
  • Lung fibre content did not match known exposure in one spinning-mill worker who mostly handled chrysotile
  • In six of the author's cases with low or moderate dust exposure, no chrysotile was detected in the lungs; the median concentration in the pleura was 3000 fibres per gram of dry tissue
  • In the author's comparison of lung and pleura (21 amosite cases, 7 chrysotile cases), the most frequent chrysotile fibre length went from 3.5 um in the lungs to 0.5 um in the pleura. Amosite changed very little.
  • In the author's rat experiment with chrysotile in peritoneal microchambers, part of the magnesium was eliminated after four weeks while silicon stayed almost constant
  • A reviewed study by Bossard et al. (21 subjects, 11 with known asbestos exposure) found no significant difference in the quantity of mineral in the lungs of exposed and nonexposed people
• The authors' conclusion: The author concluded that chrysotile is more vulnerable to chemical attack than the amphiboles and is eliminated more rapidly, and that chrysotile fibres migrate more easily into the pleura
• Limitations the authors state:
  • The author stated that the frequency and relative abundance of the various fibre types in lungs had not yet been established
  • The author stated that chrysotile bundles and aggregates cannot yet be counted properly
  • The author stated that the conclusion on airborne fibre size should rest on studies of a wider variety of jobs

Topics

Medical terms in this study, explained in our Lexicon: UICC, Asbestos-Cement, Chrysotile, Amosite, Pleura, Amphibole Group.

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