Physics and chemistry of asbestos dust

Our plain-English summary of Physics and chemistry of asbestos dust, by L. Le Bouffant (1977).

The study

• Author: L. Le Bouffant
• Published: 1977
• 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 by L. Le Bouffant was a review of papers presented at a symposium on the physics and chemistry of asbestos dust, combined with some of the author's own studies. It covered the UICC reference samples (amosite, anthophyllite, crocidolite and two chrysotiles), methods for measuring airborne fibres, and fibres found in human lungs. In the author's own work on human lung specimens, a spinning-mill worker who handled mostly chrysotile had only traces of chrysotile but many amosite fibres in the lungs. A miner exposed to chrysotile and tremolite had no remaining chrysotile but abundant tremolite. In 17 cases, the average lung-to-pleura ratio was 1.8 for chrysotile and 34.4 for amosite. This meant chrysotile was far less concentrated in the lung relative to the pleura than amosite was. In rats, short single chrysotile fibres cleared from the lungs much faster than long fibres in bundles. Chrysotile in chambers placed in rats' abdominal cavity lost 21.2% of its magnesium after four weeks. The author concluded that chrysotile is more vulnerable to chemical attack than the amphiboles, is eliminated more rapidly, 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 of papers presented at a symposium, together with the author's own laboratory, human lung-tissue and rat studies
• Who was studied: Symposium papers on asbestos dust. The author's own material included about 500 human lung specimens examined over several years, 17 cases with both lung and parietal pleura samples, and rats.
• Exposure: Asbestos fibres including the UICC reference samples (amosite, anthophyllite, crocidolite, Rhodesian chrysotile A, Canadian chrysotile B), tremolite, and asbestos-cement dust
• Main results:
  • A spinning-mill worker who handled mostly chrysotile and only small amounts of amosite had only traces of chrysotile and many amosite fibres in the lungs
  • In autopsy specimens from a man who worked in a mine with a vein containing chrysotile and tremolite, all chrysotile fibres had disappeared while tremolite was abundant
  • In 17 cases with both chrysotile and amosite counted in lung and parietal pleura, the mean lung-to-pleura ratio was 1.8 for chrysotile and 34.4 for amosite. Chrysotile was therefore much less concentrated in the lung relative to the pleura than amosite was. The author described this as less chrysotile in the lung than in the pleura.
  • In rats, short single chrysotile fibres were cleared from the lungs much more rapidly than long fibres grouped in bundles
  • Chrysotile fibres in microchambers placed in the peritoneal cavity of rats lost 21.2% of their magnesium, measured after four weeks, while silicon stayed almost constant
  • In chrysotile placed in hydrochloric acid, magnesium was released in steps rather than continuously
  • Across several hundred lungs, counts by electron microscopy and by light microscopy differed by between 10 and 10,000 times
• The authors' conclusion: The author concluded that how long fibres stay in the body depends on their resistance to chemical attack. Chrysotile is more vulnerable than the amphiboles and is eliminated more rapidly. Chrysotile fibres also migrate more easily into the pleura.
• Limitations the authors state:
  • The finding that airborne fibre size depends more on fibre type than on type of work should be based on studies of a wider variety of jobs
  • Chrysotile often forms bundles or aggregates that cannot yet be counted properly on a biologically sound basis

Topics

Medical terms in this study, explained in our Lexicon: UICC, Amosite, Anthophyllite, Crocidolite, Chrysotile, Tremolite, Pleura, Amphibole Group.

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