Quantification and Particle Size Distribution of Inhaled Fibres in the Lung

Our plain-English summary of Quantification and Particle Size Distribution of Inhaled Fibres in the Lung, by E. Bossard, I. Stolkin, M.A. Spycher, et al (1980).

The study

• Authors: E. Bossard, I. Stolkin, M.A. Spycher, J.R. Ruttner
• Published: BIOLOGICAL EFFECTS OF MINERAL FIBRES (J.C. WAGNER, EDITOR), LYON: IARC SCIENTIFIC PUBLICATIONS, VOLUME 30., PP 35-41 (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 study, from a pathology research unit at the University of Zurich, compared fibres in 21 lungs from autopsies. Ten came from people with no known occupational exposure to asbestos and 11 from men with known occupational exposure. The lung tissue was burned at low temperature, and the fibres left behind that were at least 2 micrometres long were counted with a light microscope. Mean counts were 1.5 million fibres per gram of dry lung in the unexposed group (range 0.36 to 4.8 million) and 141.9 million in the exposed group (range 0.7 to 720 million). The authors reported P = 0.05 for this difference. The most frequent fibre length in both groups was 3 to 5 micrometres. Asbestos, either chrysotile or amphibole, was found only in the exposed lungs. Total mineral content did not differ significantly between the groups. The authors found no correlation between fibre counts and lung disease, and the three mesothelioma cases had no asbestosis. A preliminary electron microscope analysis suggested that light microscopy shows only about 10% of lung fibres.

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: Comparison of fibre counts and fibre length distribution in autopsy lungs from asbestos-exposed and unexposed persons, using low-temperature incineration and phase-contrast light microscopy
• Who was studied: 21 autopsy lungs. Group NL: 10 lungs from persons with no known occupational or paraoccupational asbestos exposure (3 males and 7 women aged 28-83). Group AL: 11 lungs from males with known occupational asbestos exposure. In the AL group, asbestosis was confirmed histologically in 8 cases, and there were 3 mesotheliomas, lung carcinomas, and 1 carcinoma of the renal pelvis.
• Exposure: Known occupational asbestos exposure in the AL group. The garbled table lists jobs such as asbestos insulator and asbestos-cement worker, with asbestos types including chrysotile, amosite and crocidolite. Fibres counted were coated and uncoated fibres with a length-to-width ratio of at least 3:1 and a maximum width of 2 micrometres.
• Main results:
  • Unexposed lungs (NL): mean 1.5 million fibres per gram of dry lung weight, range 0.36 to 4.8 million (powers of ten garbled in the OCR; table header gives millions)
  • Exposed lungs (AL): mean 141.9 million fibres per gram of dry lung weight, range 0.7 to 720 million (powers of ten garbled in the OCR)
  • By the Wilcoxon ranking test, the authors reported P = 0.05 for higher fibre concentration in asbestos-exposed lungs than in normal lungs
  • The most frequent fibre length in both groups was 3-5 micrometres, making up 40-60% of fibres in normal lungs and 30-60% in exposed lungs. The authors reported that mean fibre lengths were lower in the NL group than in the AL group.
  • Asbestos, either chrysotile or amphibole, was found only in the lungs of asbestos-exposed persons. Total mineral content did not differ significantly between the exposed and unexposed groups.
  • No correlation between fibre counts and lung pathology. The three mesothelioma cases were not accompanied by asbestosis, even though their fibre counts were sometimes higher than in some cases with histologically verified asbestosis.
  • A preliminary electron microscopic analysis found that only about 10% of lung mineral fibres can be seen by light microscopy. About 90% were shorter than 2 micrometres, with a peak at 0.2-0.3 micrometres.
• The authors' conclusion: The authors concluded that low-temperature incineration was a useful method for quantifying inhaled fibres. They also concluded that lungs of people with known occupational asbestos exposure generally had a markedly higher mineral fibre content than lungs of people without known exposure.
• Limitations the authors state:
  • The counting system could clearly distinguish only fibres at least 2 micrometres long
  • Light microscopy shows only about 10% of the mineral fibres deposited in the lungs
  • Chrysotile cannot always be identified, especially in asbestosis after chrysotile exposure, which the authors attributed to its solubility in the lung

Topics

Medical terms in this study, explained in our Lexicon: Pathology, Occupational Exposure, Chrysotile, Amphibole Group, Mesothelioma.

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