A comparison of the effects of exposure of baboons to crocidolite and fibrous-glass dusts

Our plain-English summary of A comparison of the effects of exposure of baboons to crocidolite and fibrous-glass dusts, by B. Goldstein, R.E. Rendall, I. Webster (Environmental Research, 1983).

The study

• Authors: B. Goldstein, R.E. Rendall, I. Webster
• Journal: Environmental Research
• Published: 1983;32(2):344-59
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Epidemiological studies have not revealed any significant health hazards from exposure to fibrous glass and animal experiments have been inconclusive. Baboons exposed to a fibrous-glass dust cloud with size features similar to those of crocidolite asbestos developed focal peribronchiolar fibrosis with scant ferruginous body formation. The lesions were similar to those produced by crocidolite but were less extensive. No neoplasms occurred.

In plain English

This animal experiment was done at the National Centre for Occupational Health, Johannesburg, South Africa. Ten male baboons were prepared for each experiment. In dust chambers, they were exposed 7 hours a day, excluding weekends, public holidays and the week after any lung biopsy, to UICC crocidolite asbestos or Johns-Manville borosilicate fibrous glass. Doses were set to give nearly equal mean counts of airborne fibers 5 to 100 micrometers long: 1128 fibers/cm3 for crocidolite, for up to 40 months, and 1122 fibers/cm3 for fibrous glass, for up to 35 months. After 8 months, the glass-exposed baboons showed thickening of the walls of some small airways (respiratory bronchioles), with scanty ferruginous bodies. This fibrosis was slightly more marked at 18 and 30 months. It resembled the crocidolite changes, but crocidolite produced more marked fibrosis with numerous ferruginous bodies. No mesotheliomas or other lung tumors were found with either dust. The glass-related lesions showed no sign of regression six to seven months after dusting stopped. The authors concluded that fibrous-glass inhalation can cause lung fibrosis. They noted doses far above recommended values and an exposure period relatively short for judging tumors.

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 comparing two dusts, with lung biopsies taken at intervals and autopsies of animals that died
• Who was studied: Ten male baboons (Papio ursinus) of about 6-8 kg prepared for each experiment. Two animals at a time had lung biopsies, giving lung material after about 8, 18 and 30 months of exposure. National Centre for Occupational Health, Johannesburg, South Africa.
• Exposure: UICC standard reference crocidolite (North West Cape) or Johns-Manville (Canada) borosilicate fibrous glass. Dust was delivered in chambers 7 hours daily, excluding weekends, public holidays, and the week after any lung biopsy. Concentrations were aimed at equal fiber counts rather than equal weight.
• Main results:
  • The fiber counts in Table 1 are mean counts of fibers 5 to 100 micrometers long
  • Crocidolite chamber: total dust 15.83 mg/m3, respirable 13.45 mg/m3 (85%), mean count of fibers 5-100 µm long 1128 fibers/cm3, dusting for up to 40 months
  • Fibrous-glass chamber: total dust 7.54 mg/m3, respirable 5.80 mg/m3 (87%), mean count of fibers 5-100 µm long 1122 fibers/cm3, dusting for up to 35 months
  • After 8 months of fibrous-glass exposure, the walls of some respiratory bronchioles were thickened by infiltrating cells
  • In the fibrous-glass-exposed lungs, ferruginous bodies were scanty
  • Fibrosis from fibrous glass was slightly more marked at 18 and 30 months and similar to the crocidolite changes, but crocidolite produced more marked fibrosis with numerous ferruginous bodies
  • No mesotheliomas or other lung tumors were found in any animal exposed to either dust
  • Biopsies taken 6-7 months after fibrous-glass dusting ended showed no sign that the lesions were regressing
  • Lung tissue from one crocidolite-exposed animal contained on the order of 56 x 10^9 fibers per gram of dry tissue, compared with 50 x 10^6 for fibrous glass. The authors described this as a marked difference.
• The authors' conclusion: The authors concluded that fibrous-glass inhalation can cause lung fibrosis and that care must be taken when working with it. They suggested that glass fibers with dimensions comparable to asbestos fibers can produce a pneumoconiosis.
• Limitations the authors state:
  • The dust concentrations used were considerably higher than recommended values
  • The exposure period was relatively short for detecting tumors, and a much longer observation period is needed
  • Whether the fibrous-glass lesions are reversible was not yet settled. The baboons were to be observed for as long as they survived.

Topics

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

Medical terms in this study, explained in our Lexicon: Crocidolite, Fibrosis, Ferruginous body, Neoplasm.

Related studies

• The effects of asbestos-cement dust inhalation on baboons — B. Goldstein, I. Webster, et al. (1978)
• The pulmonary response to fibrous dusts of diverse compositions — P. Gross, R.T. deTreville, et al. (1970)
• Comparison of effects of glass fibre and glass powder on guinea-pig lungs — S.K. Botham, P.F. Holt (1973)
• Fibrous dust particles and ferruginous bodies. Methods for quantitating them and some results from the lungs of city dwellers — P. Gross, J. Tuma, et al. (1970)
• Fibrous glass and cancer — P.F. Infante, L.D. Schuman, et al. (1994)
• Evaluation of the deposition, translocation and pathological response of brake dust with and without added chrysotile in comparison to crocidolite asbestos following short-term inhalation: interim results — D.M. Bernstein, R. Rogers, et al. (2014)

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