A study of the length and diameter of fibres, in lung and in broncho-alveolar lavage fluid, following exposure of rats to chrysotile asbestos

Our plain-English summary of A study of the length and diameter of fibres, in lung and in broncho-alveolar lavage fluid, following exposure of rats to chrysotile asbestos, by E. Kauffer, J.C. Vigneron, A. Hesbert, et al (The Annals of Occupational Hygiene, 1987).

The study

• Authors: E. Kauffer, J.C. Vigneron, A. Hesbert, M. Lemonnier
• Journal: The Annals of Occupational Hygiene
• Published: 1987;31(2):233-40
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

This paper describes changes in the dimensions of fibres in the lungs of rats and in fibres removed from the lungs by broncho-alveolar lavage, following a single inhalation exposure to about 5 mg m-3 of chrysotile asbestos for 5 h. The lengths and diameters of fibres were measured with the transmission electron microscope. In the 90-day period following exposure, there was a progressive increase in the mean length and decrease in the mean diameter of fibres in the lungs. For fibres recovered by broncho-alveolar lavage, both the mean length and diameter decreased with time. These findings indicate that short fibres are cleared preferentially from the lung and that chrysotile fibres progressively separate into individual fibrils.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This was an animal experiment by INRS in France. Forty-eight male Sprague Dawley rats, in six groups of eight, breathed UICC Canadian chrysotile asbestos once, for 5 hours, at about 5 milligrams per cubic metre. Matching control rats breathed clean filtered air. Rats were killed at the end of exposure and 1, 7, 28 and 90 days later. Fibres in one lung lobe and in fluid washed out of the lungs (lavage) were measured by electron microscope. In the lung lobe, average fibre length rose from 5.1 to 8.6 micrometres over 90 days, and average diameter fell from 75.0 to 47.6 nanometres. In lavage fluid, both fell: length from 4.6 to 2.0 micrometres, diameter from 72.1 to 43.3 nanometres. Fibres shorter than 5 micrometres made up a falling share of lung fibres and a rising share of lavage fibres. Exposed rats had significantly more neutrophils in lavage fluid on days 1 and 7, and more multinucleated macrophages on days 28 and 90. The authors concluded that short fibres were cleared preferentially and that chrysotile fibres may progressively split into individual fibrils, which can increase fibre numbers in the lung.

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: Animal experiment: a time-course inhalation study in rats measuring fibre dimensions in lung tissue and in broncho-alveolar lavage fluid at set times after a single exposure
• Who was studied: Male Sprague Dawley rats weighing 200 to 300 g, in six exposed groups of eight (48 exposed rats). Each exposed group had its own control group of eight rats. The study was done at INRS, France; no study dates are given.
• Exposure: A single 5-hour inhalation exposure to UICC Canadian chrysotile at about 5 mg per cubic metre (measured mean 5.4 plus or minus 0.45 mg per cubic metre). Control rats breathed clean filtered air. Rats were killed at the end of exposure and 1, 7, 28 and 90 days afterwards.
• Main results:
  • Lung (diaphragmatic lobe), exposed rats: mean geometric fibre length increased from 5.1 ± 1.9 micrometres at day 0 to 8.6 ± 1.7 micrometres at day 90 (5.9, 7.2 and 7.5 at days 1, 7 and 28).
  • Lung (diaphragmatic lobe), exposed rats: mean geometric fibre diameter decreased from 75.0 ± 16.4 nm at day 0 to 47.6 ± 4.1 nm at day 90.
  • Lavage fluid, exposed rats: mean geometric fibre length decreased from 4.6 ± 1.2 micrometres at day 0 to 2.0 ± 0.4 micrometres at day 90.
  • Lavage fluid, exposed rats: mean geometric fibre diameter decreased from 72.1 ± 13.1 nm at day 0 to 43.3 ± 2.2 nm at day 90.
  • Fibres shorter than 5 micrometres fell from 54.7% to 26.0% of fibres in the lung lobe between day 0 and day 90. In lavage fluid they rose from 58.5% to 85.6%. The authors took this to mean that longer fibres are cleared less efficiently.
  • Mean fibre number in the whole diaphragmatic lobe was 0.72 ± 0.59 million at day 0 and 1.26 ± 0.43 million at day 90. The authors said this rise 'seems to indicate' that fibres splitting into fibrils produces more fibres.
  • At 90 days, mean fibre diameter in the lung (about 50 nm) was still slightly greater than that of elementary chrysotile fibrils (35 nm). The authors judged the splitting process not complete after 3 months.
  • Exposed rats had a significantly higher number of polymorphonuclear neutrophils in lavage fluid than controls on days 1 and 7. They also had more macrophages with two or more nuclei on days 28 and 90. Macrophage number and viability were not changed.
• The authors' conclusion: The authors concluded that the study suggests lung fibres may be progressively separated into individual fibrils and that their number can increase in the lung. They added that the number of fibre units likely to induce disease may be much greater than counts of airborne fibres would suggest.
• Limitations the authors state:
  • The hypochlorite digestion method used to recover fibres from lung tissue may break fibres when tissue is diced, especially long fibres.
  • Long fibres cannot be measured exactly by transmission electron microscope because of the grid bars.
  • The cell changes seen in lavage fluid are not specific to asbestos; similar responses occur with other irritants and particles.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Chrysotile, Fibril.

Related studies

• Scanning electron microscopical investigations of broncho-alveolar casts after intratracheal asbestos fibre instillation — B. Voss, T. Kerenyi, et al. (2000)
• Lung mesothelial cell and fibroblast responses to pleural and alveolar macrophage supernatants and to lavage fluids from crocidolite-exposed rats — I.Y. Adamson, H. Prieditis, et al. (1997)
• Inorganic particles in bronchoalveolar lavage fluids from nonoccupationally exposed subjects — M. Falchi, L. Biondo, et al. (1996)
• Changes in numbers and dimensions of chrysotile asbestos fibers in lungs of rats following short-term exposure — V.L. Roggli, A.R. Brody (1984)
• Experimental lung tumors following specific intrabronchial application of chrysotile asbestos. Longitudinal light and electron microscopic investigations in rats — E. Fasske (1988)
• Forsterite exposure causes less oxidative DNA damage and lung injury than chrysotile exposure in rats — A. Takata, H. Yamauchi, et al. (2009)

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