Comparison of effects of glass fibre and glass powder on guinea-pig lungs

Our plain-English summary of Comparison of effects of glass fibre and glass powder on guinea-pig lungs, by S.K. Botham, P.F. Holt (British Journal of Industrial Medicine, 1973).

The study

• Authors: S.K. Botham, P.F. Holt
• Journal: British Journal of Industrial Medicine
• Published: 1973;30(3):232-6
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Botham, Susan K., and Holt, P. F. (1973).British Journal of Industrial Medicine,30, 232-236. Comparison of effects of glass fibre and glass powder on guinea-pig lungs. Following 24 hours inhalation by guinea-pigs of powdered glass dust, the pulmonary effects over the succeeding month differed from those previously observed to follow inhalation of glass fibre in that (1) fewer erythrocytes escaped from the capillaries, (2) very few giant cells were produced, (3) erythrocytes and intracellular glass particles were cleared more readily because junctions between respiratory and terminal bronchioles were not blocked by giant cells, (4) intracellular granules containing Perls-positive material did not appreciably increase in number or intensity of staining during the month, and (5) particles were not coated with Perls-positive material during the time that pseudo-asbestos bodies would be formed from glass fibres. The difference between the effects of chemically similar glass powder and fibre during a month in a guinea-pig lung is considered to be due to the morphology of the inhaled particle.

In plain English

This was an animal experiment. The authors ground glass into a fine powder of irregular particles, most under about 10 micrometres across. Ten male albino guinea-pigs breathed a high concentration of it. One animal was killed after 3 hours. The rest were exposed for 24 hours and killed at intervals from 1 to 28 days after dusting began. Two unexposed control animals were also examined. The authors compared these lungs with what they had previously described after guinea-pigs inhaled glass fibre of the same composition. After glass powder, red blood cells appeared in the airways, but fewer than after glass fibre. Giant cells were very rare. Glass-laden macrophages appeared in airway debris of every exposed animal, but detached cells holding both glass and iron-staining material were gone by 28 days. Powder particles did not become coated with iron-staining material, as some long glass fibres do when forming pseudo-asbestos bodies. The authors concluded that the differences came from particle shape, not chemical composition. They reasoned that the effects of asbestos are also due to fibre shape.

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 inhalation experiment (lung tissue examined under the microscope), compared with the authors' earlier published glass fibre experiment
• Who was studied: Ten albino male guinea-pigs exposed to glass powder, plus two control animals; Department of Chemistry, University of Reading; dates of the experiment not given
• Exposure: Powdered glass made by grinding fused glass spheres (supplied by Johns-Manville Fiber Glass Inc.). Particles were irregular, most under about 10 micrometres, occasionally up to 100 micrometres. One animal was exposed for 3 hours, the rest for 24 hours, at a 'high concentration' that was not given as a number. Animals were killed 1, 2, 3, 4, 5, 7, 14, 21 and 28 days after dusting began.
• Main results:
  • Red blood cells were present in the airway debris of all exposed guinea-pigs, even the one killed after 3 hours, and their number decreased over time.
  • Red cells in the respiratory bronchioles of the glass powder animals were less numerous than those the authors had previously seen within a week after glass fibre inhalation.
  • Giant cells were rare after glass powder. After glass fibre, macrophages had often fused around long fibres to form giant cells.
  • Macrophages containing many fine glass particles were found in the airway (bronchiolar) debris of all guinea-pigs.
  • Detached cells containing both glass particles and iron-staining material formed loose plugs in the airways at seven days. They were found only in larger bronchioles at 14 and 21 days, and those air spaces had cleared by 28 days.
  • Some long glass fibres become coated with iron-protein material to form pseudo-asbestos bodies within a month, but glass powder particles did not become coated.
  • Macrophages with iron-staining (Perls-positive) granules were few in the first week and more numerous in the last three animals. However, the amount of iron after one month was much less than in lungs containing an inhaled fibrous dust.
  • No iron-staining material or glass particles were found in lymphoid tissue in the lungs of any guinea-pig given powdered glass.
• The authors' conclusion: The authors concluded that the different responses came from changing the shape of the inhaled dust, not its chemical composition. They considered it reasonable to deduce that the pathological effects of asbestos are also due to fibre shape.
• Limitations the authors state:
  • The authors noted they could not prove that the iron-staining granules contained no minute glass fragments, although the granules were generally much smaller than most glass particles.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Bodies.

Related studies

• The development of glass-fibre bodies in the lungs of guinea-pigs — S.K. Botham, P.F. Holt (1971)
• Comparison of effects on macrophage cultures of glass fibre, glass powder, and chrysotile asbestos — E.G. Beck, P.F. Holt, et al. (1972)
• Development of asbestos bodies on amosite, chrysotile and crocidolite fibres in guinea-pig lungs — S.K. Botham, P.F. Holt (1971)
• Asbestos-body formation in the lungs of rats and guinea-pigs after inhalation of anthophyllite — S.K. Botham, P.F. Holt (1972)
• A comparison of the effects of exposure of baboons to crocidolite and fibrous-glass dusts — B. Goldstein, R.E. Rendall, et al. (1983)
• A comparison of the cytogenetic response to asbestos and glass fibre in Chinese hamster and human cell lines. Demonstration of growth inhibition in primary human fibroblasts — A.M. Sincock, J.D. Delhanty, et al. (1982)

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