Assessment of the toxicity of man-made fibres. A final report of a workshop held in Paris, France 3-4 February 1994

Our plain-English summary of Assessment of the toxicity of man-made fibres. A final report of a workshop held in Paris, France 3-4 February 1994, by J. Bignon, P. Brochard, R. Brown, et al (The Annals of Occupational Hygiene, 1995).

The study

• Authors: J. Bignon, P. Brochard, R. Brown, J.M. Davis, V. Vu, G. Gibbs, M. Greim, G. Oberdörster, P. Sébastien
• Journal: The Annals of Occupational Hygiene
• Published: 1995;39(1):89-106
• Type of article: Review
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

This report summarized a workshop held in Paris, France, on 3-4 February 1994. The workshop examined experimental methods for identifying man-made fibres (MMFs) that pose a significant carcinogenic risk to humans. More than 130 scientists, government officials and industry representatives attended. It covered three themes: a priori risk criteria, detection and screening assays, and inhalation tests. Nineteen scientists presented papers. Rapporteurs summarized the papers and discussions, and all participants reviewed the summaries paragraph by paragraph. The meeting aimed to record agreement where it existed rather than to reach consensus.

Presenters reported the following:

• In vitro dissolution rates could predict the dissolution of long (>20 µm) fibres in rat lungs.
• Long glass fibres were cleared faster than short ones.
• In rat inhalation studies, chrysotile and crocidolite asbestos and refractory ceramic fibre (RCF 1) produced fibrosis, lung tumours and mesothelioma. RCF produced a 42% mesothelioma incidence in hamsters.
• Glass wool and slag wool did not significantly increase lung tumours. Rock wool caused minimal fibrosis.
• Participants disagreed about the value of intraperitoneal injection tests.
• One presenter estimated that humans had a tumour risk from asbestos at fibre concentrations 300 times lower than those needed in rats. He concluded that rat inhalation studies were not sensitive enough to detect hazard and risk in humans exposed to asbestos.

The workshop generally agreed that properly designed long-term inhalation studies were relevant to assessing MMF hazard. It did not fully agree on their sensitivity or on the need for a second species. Recommendations included:

• standardized tests and interlaboratory comparisons;
• reference asbestos and erionite fibres;
• a multi-dose asbestos inhalation study to compare rats and humans;
• studies of fibre burden in human lungs.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This article is the final report of a workshop, summarizing papers by 19 scientists and the discussions that followed; it is not a single study. On 3-4 February 1994, more than 130 participants met in Paris to discuss laboratory methods for judging whether man-made fibres could cause cancer in humans. Presenters described rat inhalation studies in which chrysotile and crocidolite asbestos and refractory ceramic fibre (RCF 1) caused fibrosis, lung tumours and mesothelioma. In hamsters, RCF at the same exposure level used in those rats, 30 mg per cubic metre, produced a 42% incidence of mesotheliomas. In the rat studies, the two glass fibres, slag wool and rock wool tested, each at three doses, showed no significant lung cancer excess over filtered-air controls, and no mesotheliomas at 30 mg per cubic metre. One presenter argued that rat inhalation studies are not sensitive enough to detect asbestos hazard in humans. Participants disagreed about tests that inject fibres into the abdominal cavity. The workshop generally agreed that properly designed long-term inhalation studies are relevant to judging human hazard from man-made fibres. The meeting did not seek consensus, and complete agreement was not reached on some issues.

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: Workshop report: summaries of presented papers and discussions, followed by recommendations for research. It is not an original study.
• Who was studied: More than 130 scientists, government officials and industry representatives meeting in Paris, France, on 3-4 February 1994. Papers were presented by 19 scientists. The studies discussed were mainly in rats and hamsters.
• Exposure: Man-made fibres, including refractory ceramic fibres, glass fibres, stone (rock) wool, slag wool and para-aramid (Kevlar) fibrils. Chrysotile, crocidolite and tremolite asbestos were used as comparison or control fibres in the studies presented.
• Main results:
  • One presenter reported that, in rats in the RCC inhalation studies, exposure to chrysotile and crocidolite asbestos produced pulmonary fibrosis and significant increases in lung tumours and mesothelioma.
  • The same presenter reported that refractory ceramic fibre (RCF 1) at 30 mg per cubic metre (approximately 190 fibres per ml) also produced fibrosis, lung tumours and mesothelioma in rats. In hamsters, this same exposure level produced a 42% incidence of mesotheliomas.
  • In rats exposed at 30 mg per cubic metre, fibre glass (MMVF 10 and 11) and slag wool (MMVF 22) did not produce mesotheliomas or a significant increase in lung tumour incidence compared with the negative control group. Rock wool (MMVF 21) caused minimal fibrosis, no mesotheliomas and no statistically significant increase in lung tumours.
  • A statistical analysis presented at the workshop covered four insulation wools (two fibrous glasses, a stone wool and a slag wool), each tested in rats at three dose levels. It found no significant excess of lung cancer in any of the 12 exposure groups compared with concurrent filtered-air controls. At lower doses of kaolin RCF, there was one mesothelioma among 379 rats.
  • In intraperitoneal injection tests reported by one presenter, the asbestos samples and three fine fibre fractions of commercial glass wool and stone wool gave positive results. Slag wool and another experimental fibre had not produced significant tumour rates up to 90 and 70 weeks respectively.
  • One presenter compared human and rat data and reported that humans had a tumour risk at workplace fibre concentrations 300 times lower than those needed to produce the same risk in rats. The presenter concluded that rat inhalation studies are not sensitive enough to detect hazard in humans exposed to asbestos.
  • For para-aramid fibrils, an international panel of pathologists diagnosed the rat lung lesions as 'proliferative keratin cyst'. All panel participants agreed the lesions were not malignant neoplasms.
  • Participants disagreed about the strengths and limitations of intraserosal (injection) tests.
• The authors' conclusion: The workshop generally agreed that long-term inhalation studies are relevant to evaluating the hazard of man-made fibres for humans, provided they are appropriately designed and conducted. It recommended standardized test systems and interlaboratory comparisons.
• Limitations the authors state:
  • The meeting was not aimed at reaching consensus, only at recording agreement where it existed.
  • There was no complete agreement on the sensitivity and specificity of rat inhalation studies, or on the need for a second test species.
  • The human-versus-rat comparison used human risk estimates from chrysotile textile workers, while the rat risk estimates came from amphibole exposure.
  • Interspecies differences in how fibres are transported to the pleura mean animal data may not apply to humans.

Topics

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

Medical terms in this study, explained in our Lexicon: Carcinogenic, Chrysotile, Crocidolite, Fibrosis, Mesothelioma, erionite.

Related studies

• Low dose exposure to natural and man made fibres and the risk of cancer: towards a collaborative European epidemiology. Report of a workshop held in Paris , 10-12 June, 1991 — A.J. Valleron, J. Bignon, et al. (1992)
• Man-made mineral fiber hazardous properties assessment using transgenic rodents: example of glass fiber testing — M.C. Bottin, J.C. Vigneron, et al. (2003)
• Lung dust analysis in the assessment of past exposure of man-made mineral fibre workers — J.C. McDonald, B.W. Case, et al. (1990)
• Long-term health effects in hamsters and rats exposed chronically to man-made vitreous fibres — D.M. Smith, L.W. Ortiz, et al. (1987)
• Persistence of man-made mineral fibres (MMMF) and asbestos in rat lungs — B. Bellmann, H. Muhle, et al. (1987)
• Formation of 8-hydroxydeoxyguanosine by asbestos and man made mineral fibres — P. Leanderson, P. Söderkvist, et al. (1988)

Browse more research in The Annals of Occupational Hygiene, or return to medical research.