Comparison of Length-Dependent Cytotoxicity Inhalable Asbestos and Man-Made Mineral Fibres

Our plain-English summary of Comparison of Length-Dependent Cytotoxicity Inhalable Asbestos and Man-Made Mineral Fibres, by F. Tilkes, E.G. Beck (1980).

The study

• Authors: F. Tilkes, E.G. Beck
• Published: BIOLOGICAL EFFECTS OF MINERAL FIBRES (J.C. WAGNER, EDITOR), LYON: IARC SCIENTIFIC PUBLICATIONS, VOLUME 30., PP 475-483 (1980)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This laboratory study, from the Hygiene Institute of Justus Liebig University in Giessen, Germany, tested in cell culture whether fibre length affects how harmful fibres are to cells. The authors used phagocytic (particle-engulfing) ascites tumour cells obtained from Wistar rats that had been given nemalite into the abdominal cavity. They exposed the cells to chrysotile, crocidolite and amosite asbestos, each in three defined length fractions, and to glass fibres in four length fractions. Doses were given both by weight and by fibre number. They measured DNA and protein synthesis, cell numbers, and release of the enzyme LDH. For all three asbestos types, DNA synthesis fell as fibre length increased. Glass fibres also showed toxicity rising with length. Dosed by fibre number, amosite and chrysotile appeared similarly toxic. Dosed by weight, the 'modified UICC' samples of amosite, crocidolite and glass fibres were much less toxic than chrysotile, particularly at low concentrations. The authors concluded that asbestos toxicity increases with fibre length. They also concluded that glass fibres with lengths and diameters similar to asbestos showed comparable toxicity in vitro.

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: In vitro (cell culture) experiment comparing length fractions of asbestos and glass fibres. Tests were done in triplicate and repeated at least once.
• Who was studied: Phagocytic ascites tumour cells induced in Wistar rats after intraperitoneal administration of nemalite, studied at the Hygiene Institute of Justus Liebig University, Giessen, Federal Republic of Germany.
• Exposure: Chrysotile, crocidolite and amosite asbestos, each in three length fractions ('modified UICC' F, fine FF, ultrafine fF). Glass fibres in four length fractions (ultrafine fF, fine FF, and Johns Manville MN 100 and MN 104). Doses were given both by weight (for example 30 ug/ml) and by fibre number.
• Main results:
  • With all three asbestos types, DNA synthesis in the cells decreased as fibre length increased. This was also seen in cell counts.
  • With amosite, especially the fine fraction, numerous two- and multinucleated cells were seen. The authors related this to a possible disturbance of cell division.
  • With chrysotile, toxicity increased linearly with increasing fibre number.
  • When doses were given by fibre number, amosite and chrysotile appeared similar in toxicity, despite their different diameters and chemical compositions.
  • When doses were given by weight, the modified UICC samples of amosite, crocidolite and glass fibres, particularly at low concentrations, were much less toxic than the corresponding chrysotile fraction. Toxicity became comparable only at higher fibre concentrations.
  • The dose-effect curves for amosite and chrysotile, and for crocidolite, seemed to indicate an effective threshold.
  • Glass fibres also showed toxicity increasing consistently with length. The fine glass fibre fractions were similar in toxicity to one another, with a clear difference for the ultrafine fraction.
  • The ultrafine glass fibres did not cause an elevated LDH release.
• The authors' conclusion: The authors concluded that asbestos fibre toxicity increases with increasing length. Chrysotile and amosite toxicity was similar when doses were given by fibre number, and crocidolite approached chrysotile only at high concentrations. Glass fibres with length and diameter distributions similar to asbestos showed comparable toxicity in vitro. The authors added that initial results of uncompleted animal experiments, using intraperitoneal injection of the same dusts, indicated that toxicity in vitro correlated with carcinogenic potency in vivo.

Topics

Medical terms in this study, explained in our Lexicon: Ascites, Chrysotile, Crocidolite, Amosite, UICC.

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