Pulmonary response of hamsters to fibrous glass: chronic effects of repeated intratracheal instillation with or without benzo\[a\]pyrene

Our plain-English summary of Pulmonary response of hamsters to fibrous glass: chronic effects of repeated intratracheal instillation with or without benzo[a]pyrene, by V.J. Feron, P.M. Scherrenberg, H.R. Immel, et al (Carcinogenesis, 1985).

The study

• Authors: V.J. Feron, P.M. Scherrenberg, H.R. Immel, B.J. Spit
• Journal: Carcinogenesis
• Published: 1985;6(10):1495-9
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Syrian golden hamsters were given intratracheal instillations of glass fibres with or without benzo[a]pyrene suspended in saline, once a fortnight for 52 weeks. The experiment was terminated at week 85. 'Silicotic granulomas' consisting of tightly packed, iron-positive macrophages filled with glass fibres and surrounded by a layer of alveolar epithelial cells were the predominant pulmonary lesion. No mesotheliomas or other tumours of the respiratory tract were observed in hamsters treated with glass fibres alone. There was no indication that glass fibres enhanced the development of respiratory tract tumours induced by benzo[a]pyrene. In hamsters similarly exposed to crocidolite fibres with or without benzo[a]pyrene no mesotheliomas or other respiratory tract tumours were observed either. An explanation for the absence of pulmonary tumours might be that repeated administration of fibres over a period of 52 weeks entails an acute pulmonary reaction after each administration with the implication that the fibres cannot settle down well enough to be able to induce tumours. Another possible explanation is the relatively short duration of the experimental period.

In plain English

This was an animal experiment in Syrian golden hamsters in the Netherlands. Six groups, each of 35 males and 35 females, had material placed into the windpipe once every two weeks for 52 weeks: saline (controls), benzo[a]pyrene (BaP, a cancer-causing chemical), glass fibres, glass fibres plus BaP, crocidolite asbestos, or crocidolite plus BaP. Survivors were killed at week 85. Respiratory tract tumours were found only in groups given BaP: 7/63 (11%) with BaP alone, 4/66 (6%) with BaP plus glass fibres and 4/52 (8%) with BaP plus crocidolite. No mesotheliomas or other respiratory tract tumours were seen with glass fibres or crocidolite alone. Glass fibres produced 'silicotic granulomas', clumps of fibre-filled cells in the lung. Crocidolite produced asbestos bodies and focal lung fibrosis. The authors concluded that neither fibre increased BaP tumours here, but that the conditions were most probably unsuitable to detect such an effect. They suggested that high, early mortality and the early end of the experiment might mainly explain the negative results.

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: long-term study with repeated intratracheal instillation in hamsters
• Who was studied: Syrian golden hamsters, about 16 weeks old at the start, from a randomly bred colony in Zeist, The Netherlands. Six groups of 35 males and 35 females each.
• Exposure: Intratracheal instillations given fortnightly for 52 weeks. Group 1 got saline-gelatin (control). Group 2 got 1 mg BaP. Group 3 got 1 mg glass microfibres (code 104, Johns-Manville). Group 4 got 1 mg glass fibres plus 1 mg BaP. Group 5 got 1 mg UICC crocidolite. Group 6 got 1 mg crocidolite plus 1 mg BaP. The total was 26 mg of fibres. The experiment ended at week 85.
• Main results:
  • Respiratory tract tumours occurred only in hamsters given BaP, alone or with glass or crocidolite fibres
  • Respiratory tract tumour incidence was 7/63 (11%) in the BaP alone group, 4/66 (6%) in the BaP plus glass fibres group and 4/52 (8%) in the BaP plus crocidolite group
  • The only two peripheral lung tumours were adeno-squamous carcinomas, both in the BaP plus crocidolite group
  • No mesotheliomas or other respiratory tract tumours were seen in hamsters given glass fibres alone
  • In hamsters given glass fibres, the main lung lesion was 'silicotic granulomas' of tightly packed macrophages filled with glass fibres
  • In crocidolite-treated hamsters, focal pulmonary fibrosis and calcareous foci within asbestos granulomas were common; mesotheliomas were not observed
  • There was no relevant difference in mortality between any treatment group and the control group
• The authors' conclusion: The authors concluded that, under the conditions of this experiment, glass fibres did not enhance BaP-induced respiratory tract tumours. The same held for crocidolite, so the experimental conditions most probably were inappropriate to detect possible co-carcinogenic properties of glass fibres.
• Limitations the authors state:
  • The authors stated that high and early mortality and the relatively early termination of the experiment might be primarily responsible for the negative results
  • The authors reported mortality of 45% in males and 90% in females after 85 weeks
  • The authors suggested that repeated dosing over one year may have caused an acute lung reaction after each dose, so the fibres could not settle in the tissue
  • Crocidolite also showed no co-carcinogenic effect with BaP, although other investigators had reported one, which casts doubt on the sensitivity of the test conditions

Topics

Medical terms in this study, explained in our Lexicon: Granuloma, Macrophage, Mesothelioma, Crocidolite.

Related studies

• Morphological transformation of Syrian hamster embryo cells induced by mineral fibres and the alleged enhancement of benzo[a]pyrene — S.O. Mikalsen, E. Rivedal, et al. (1988)
• Chronic inhalation study of fiber glass and amosite asbestos in hamsters: twelve-month preliminary results — T.W. Hesterberg, C. Axten, et al. (1997)
• Asbestos and benzo[a]pyrene act synergistically to induce squamous metaplasia and incorporation of [3H]thymidine in hamster tracheal epithelium — B.T. Mossman, A. Eastman, et al. (1984)
• Comparison of functional, biochemical, and morphometric alterations in the lungs of 4 rat strains and hamsters following repeated intratracheal instillation of crocidolite asbestos — D.J. Padilla-Carlin, D.L. Costa (2011)
• Increased 8-hydroxyguanine in DNA and its repair activity in hamster and rat lung after intratracheal instillation of crocidolite asbestos — R. Yamaguchi, T. Hirano, et al. (1999)
• Studies on the inhalation toxicology of two fiberglasses and amosite asbestos in the Syrian golden hamster. Part II. Results of chronic exposure — E.E. McConnell, C. Axten, et al. (1999)

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