Genotoxicity of dimethylnitrosamine in the presence of chrysotile asbestos UICC B and xonotlite

Our plain-English summary of Genotoxicity of dimethylnitrosamine in the presence of chrysotile asbestos UICC B and xonotlite, by F. Denizeau, M. Marion, G. Chevalier, et al (Carcinogenesis, 1985).

The study

• Authors: F. Denizeau, M. Marion, G. Chevalier, M.G. Cote
• Journal: Carcinogenesis
• Published: 1985;6(12):1815-7
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Interactions of particulates with chemical genotoxic agents may play an important role in the induction of carcinogenesis. With respect to bronchogenic cancer, the synergism associated with combined exposure to asbestos and tobacco smoke is a well-documented phenomenon. The present work focused on chrysotile asbestos and xonotlite. The latter is a fibrous calcium silicate which is increasingly being used to replace asbestos in various industrial applications. The study was aimed at testing the possible interaction of these materials with dimethylnitrosamine (DMN), a genotoxic component of tobacco smoke. The capacity of fibers to interfere with the genotoxic response elicited by DMN in the UDS/hepatocyte assay system specifically designed for sensitive detection of short-patch DNA repair, was looked for. The properties of the selected fibers with respect to binding affinity towards DMN were also examined.

In plain English

This short laboratory report from Canada tested, in liver cells (hepatocytes) taken from rats and grown in dishes, whether chrysotile asbestos (UICC B) or xonotlite changed the DNA-damaging effect of dimethylnitrosamine (DMN), a genotoxic chemical found in tobacco smoke. Xonotlite is a fibrous calcium silicate used as an asbestos substitute. Cells were exposed to DMN alone, to each fiber alone, or to DMN plus a fiber. The authors then measured DNA repair activity (unscheduled DNA synthesis), with the chemical 2-acetylaminofluorene as a positive control. Each of six experiments used cells from one animal. DMN produced a dose-dependent response, while neither fiber alone showed a significant genotoxic effect. Adding chrysotile or xonotlite did not change the response to DMN, and the fibers did not harm the cells as measured by release of the enzyme lactate dehydrogenase. In tests lasting up to 5 hours, neither fiber significantly bound DMN. The authors concluded that interactions of chrysotile with DMN were not apparent in this system, and that fiber type and the kind of chemical may help determine whether such interactions occur.

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: Laboratory (in vitro) experiment using primary cultures of rat liver cells, published as a short communication
• Who was studied: Primary cultures of rat hepatocytes. Six experiments were run, each with cells from one animal and three Petri dishes per condition.
• Exposure: Chrysotile asbestos UICC B and synthetic xonotlite fibers, each alone and each mixed with DMN (5 mM and 10 mM according to the table). DMN alone was also tested, and 2-acetylaminofluorene (2-AAF) was used as a positive control. The xonotlite fibers examined were all under 2 micrometres long, with a diameter of about 0.1 micrometre or less.
• Main results:
  • DMN alone produced a dose-dependent DNA repair (unscheduled DNA synthesis) response in the hepatocytes.
  • The positive control, 2-AAF, also produced a clear response.
  • Chrysotile asbestos alone and xonotlite alone showed no significant genotoxic effect.
  • In cells given DMN plus chrysotile, the response was comparable to that with DMN alone.
  • In cells given DMN plus xonotlite, the DMN response appeared unaffected.
  • The fibers did not damage the cells, measured by release of the enzyme lactate dehydrogenase (LDH). This held for fibers alone and for fibers with DMN.
  • Neither chrysotile nor xonotlite significantly bound radioactive DMN during incubations of up to 5 hours.
• The authors' conclusion: The authors concluded that, in their system, interactions of chrysotile with DMN were not apparent. They also concluded that the type of fiber and the nature of the genotoxic compound may help determine whether fibers and carcinogens interact synergistically.

Topics

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

Medical terms in this study, explained in our Lexicon: Genotoxicity, Chrysotile, UICC, Carcinogenesis, Bronchogenic Carcinoma, Silicate.

Related studies

• Relative effects of asbestos and wollastonite on alveolar macrophages — W.H. Pailes, D.J. Judy, et al. (1984)
• Biological reactivity of calcium silicate composites--in vitro studies — J. Hunt, F.D. Pooley, et al. (1981)
• The biological reactivity of calcium silicate composites: in vivo studies — R.J. Richards, T.D. Tetley, et al. (1981)
• Cytotoxicity of respirable dusts from industrial minerals: comparison of two naturally occurring and two man-made silicates — D. Nadeau, L. Fouquette-Couture, et al. (1987)
• Mortality among a cohort of US man-made mineral fiber workers: 1985 follow-up — G.M. Marsh, P.E. Enterline, et al. (1990)
• Wollastonite exposure and lung fibrosis — M.S. Huuskonen, A. Tossavainen, et al. (1983)

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