An in vitro/in vivo study into the short term effects of exposure to mineral fibres

Our plain-English summary of An in vitro/in vivo study into the short term effects of exposure to mineral fibres, by A. Clouter, C.E. Houghton, C.A. Bowskill, et al (Experimental and Toxicologic Pathology, 1996).

The study

• Authors: A. Clouter, C.E. Houghton, C.A. Bowskill, J.A. Hoskins, R.C. Brown
• Journal: Experimental and Toxicologic Pathology
• Published: 1996;48(6):484-6
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher

In plain English

This short report described an experiment in rats and in lung cells. Male F344 rats, 36 per group, inhaled either calcium sulphate fibres or crocidolite asbestos through a nose-only system for 6 hours a day, 5 days a week, for 3 weeks. Eighteen rats per group were killed immediately and the rest after 3 weeks without exposure. The authors found no significant difference between groups in macrophages per alveolus, and neither fibre changed protein levels or gamma-GT enzyme activity in lung washings. Non-protein sulphydryl (NPSH) levels rose in calcium sulphate-exposed rats after the 3-week recovery period. Crocidolite did not affect NPSH at either time point. The alveoli of crocidolite-exposed rats contained much cell debris that appeared to be damaged macrophages. Lung type II cells exposed to either fibre in culture showed no change in alkaline phosphatase staining. The authors proposed that the NPSH rise was a protective response to oxidant damage, and that its absence left the lung lining of crocidolite-exposed rats exposed. They noted that inflammation may have been localised, and that the cell result may reflect the absence of other cell types.

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 (nose-only inhalation exposure of rats) combined with an in vitro study of isolated rat lung type II cells
• Who was studied: Male F344 rats, 36 per group, weighing 130-150 g; 18 per group killed immediately after exposure and the remainder after 3 weeks without exposure; type II lung cells isolated from unexposed and calcium sulphate-exposed rats; study from the MRC Toxicology Unit, University of Leicester, UK
• Exposure: Inhaled aerosol of calcium sulphate fibres (Franklin fibre A-30, US Gypsum) or crocidolite, for 6 hours a day, 5 days a week, for 3 weeks. The aerosol concentration is printed as '100' followed by a unit that is garbled in the scan. In vitro, type II cells were exposed overnight to calcium sulphate or crocidolite at 2.5, 5, 7.5, 12.5 or 25 micrograms per ml.
• Main results:
  • No significant difference was found between groups in the number of macrophages per alveolus in rats exposed to calcium sulphate or crocidolite
  • Exposure to either fibre did not alter protein concentration or gamma-GT activity in lung lavage fluid
  • NPSH levels increased in rats exposed to calcium sulphate after 3 weeks of no exposure
  • Exposure to crocidolite did not affect NPSH levels at either time point
  • The alveoli of crocidolite-exposed rats contained a large amount of cell debris that appeared to be the remains of damaged macrophages
  • Viability of type II cells from rats pre-exposed to calcium sulphate was unchanged compared with cells from unexposed rats
  • Type II cells from control rats incubated with calcium sulphate or crocidolite showed no change in alkaline phosphatase staining at any concentration tested
• The authors' conclusion: The authors proposed that the NPSH increase in rats exposed to the non-toxic fibre (calcium sulphate) is a response to protect the lungs from oxidant damage, and that the lack of this response in crocidolite-exposed rats left their lung epithelium exposed, possibly because of the damage suggested by the cell debris
• Limitations the authors state:
  • The macrophage counts showed no inflammatory response, but the authors noted that inflammation may have been localised to the acini region
  • The lack of effect on isolated type II cells may be due to the absence of other interacting cell types
  • The in vitro doses were low: the authors noted that other workers reported toxicity at a much higher crocidolite dose (250 micrograms per ml)

Topics

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

Related studies

• Short-term inhalation and in vitro tests as predictors of fiber pathogenicity — R.T. Cullen, B.G. Miller, et al. (1997)
• Biopersistence of rock wool in lungs after short-term inhalation in rats — Y. Kudo, Y. Aizawa (2008)
• Benzo[a]pyrene-enhanced mutagenesis by man-made mineral fibres in the lung of lamda-lacI transgenic rats — J. Topinka, P. Loli, et al. (2006)
• Role of fibre characteristics on cytotoxicity and induction of anaphase/telophase aberrations in rat pleural mesothelial cells in vitro: correlations with in vivo animal findings — M. Yegles, X. Janson, et al. (1995)
• New insights into the toxicity of mineral fibres: A combined in situ synchrotron μ-XRD and HR-TEM study of chrysotile, crocidolite, and erionite fibres found in the tissues of Sprague-Dawley rats — A.F. Gualtieri, N. Bursi Gandolfi, et al. (2017)
• Short-term crocidolite inhalation studies in mice: validation of an inhalation chamber — B. Rihn, E. Kauffer, et al. (1996)

Browse more research in Experimental and Toxicologic Pathology, or return to medical research.