In vitro assessment of asbestos genotoxicity

Our plain-English summary of In vitro assessment of asbestos genotoxicity, by F.B. Daniel (Environmental Health Perspectives, 1983).

The study

• Author: F.B. Daniel
• Journal: Environmental Health Perspectives
• Published: 1983;53:163-7
• Type of article: Review
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Asbestos fibers are highly cytotoxic to cultured mammalian cells and produce chromosomal aberrations in several rodent cell types. There is some uncertainty in the literature as to whether these fibers are clastogenic to cultured human cells. Asbestos fibers do not produce either DNA damage or back mutations in prokaryotic assay systems, and they do not appear to cause DNA strand breaks in either rodent or human cells. The evidence that these fibers can produce either forward mutation or neoplastic transformation of mammalian cells is weak. Asbestos fibers are clearly oncogenic to humans and animals, but, except for clastogenic effects in rodent cells, there is little evidence for genotoxicity of fibers. It is reasonable to expect, therefore, that these materials may be oncogenic by virtue of mechanisms rather than as tumor initiators.

In plain English

This 1983 article was a review, not a new experiment. The author examined published laboratory ('short-term') tests of whether asbestos fibers damage genetic material. It focused mainly on UICC and NIEHS standard reference samples of chrysotile, crocidolite, amosite and other asbestos types. The author judged that asbestos caused neither DNA damage nor back mutations in bacteria, and that attempts to show DNA damage or strand breakage in mammalian cells had been negative. The reviewed studies showed chromosome aberrations in cultured rodent cells, but the evidence for human cells was contradictory. Evidence for sister chromatid exchanges was negative or extremely weak, and evidence for gene mutation or neoplastic transformation in cultured mammalian cells was weak. Work from the author's laboratory found that chrysotile applied before benzo(a)pyrene increased that chemical's binding to DNA in cultured human fibroblasts. The author concluded that tumor initiation was possible, but that other mechanisms, such as acting as a cocarcinogen or promoter, may better explain asbestos's oncogenic potential. The author added that a definitive statement on the fibers' genotoxic potential may require more experimentation.

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: review of published in vitro (laboratory) genotoxicity studies
• Who was studied: Published laboratory studies on bacteria, cultured rodent cells and cultured human cells, mostly using UICC and NIEHS standard reference asbestos fibers
• Exposure: Asbestos fibers including chrysotile, amosite, anthophyllite and crocidolite (largely UICC and NIEHS reference samples), with glass fibers in some comparisons
• Main results:
  • In the author's assessment, asbestos fibers did not induce DNA damage or back-mutation in bacterial cells
  • Attempts to show DNA strand breakage or DNA damage in mammalian cells after asbestos exposure had been negative
  • The author judged that asbestos fibers can produce chromosomal aberrations in rodent cells
  • The evidence for chromosomal effects in cultured human cells was contradictory
  • UICC asbestos fibers were either negative or extremely weak at producing sister chromatid exchanges (SCE) in mammalian cells
  • The evidence that asbestos fibers themselves cause neoplastic transformation or gene mutation in cultured mammalian cells was described as weak
  • In the author's laboratory, NIEHS chrysotile applied before benzo(a)pyrene increased the chemical's DNA binding and enhanced its cytotoxic effects in cultured human fibroblasts
  • Adding NIEHS chrysotile and benzo(a)pyrene at the same time to normal human fibroblasts did not increase benzo(a)pyrene metabolism
  • The author wrote that these studies may indicate asbestos fibers act at the level of a cocarcinogen or promoter
• The authors' conclusion: The author concluded that asbestos fibers might act at tumor initiation through chromosome damage, but that it may be more reasonable to look to other mechanisms to explain their oncogenic potential.
• Limitations the authors state:
  • The author stated that more experimentation may be required before a definitive statement on asbestos genotoxicity can be made
  • The author noted that 'asbestos' covers many fibrous minerals with varied properties that can affect carcinogenic potential
  • Negative bacterial results may partly reflect that bacteria do not take up asbestos fibers
  • The reason for the conflicting human-cell results could not be determined, because the two studies used different cell and fiber types

Topics

Medical terms in this study, explained in our Lexicon: Genotoxicity.

Related studies

• In vitro studies on the biologic effects of fibers: correlation with in vivo bioassays — B.T. Mossman (1990)
• Mechanistic in vitro studies: What they have told us about carcinogenic properties of elongated mineral particles (EMPs) — B.T. Mossman (2018)
• Carboxylated short single-walled carbon nanotubes but not plain and multi-walled short carbon nanotubes show in vitro genotoxicity — M. Mrakovcic, C. Meindl, et al. (2015)
• In vitro genotoxicity studies of chrysotile asbestos fibers dispersed in simulated pulmonary surfactant — J. Lu, M.J. Keane, et al. (1994)
• A study of the effect of chrysotile fiber surface composition on genotoxicity in vitro — M.J. Keane, J.W. Stephens, et al. (1999)
• Appropriate in vitro test conditions for genotoxicity testing of fibers — G. Speit (2002)

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