Chrysotile, tremolite and carcinogenicity

It has been suspected for many years that amphibole fibres in the tremolite series, a low level contaminant of chrysotile asbestos, may contribute disproportionately to the incidence of mesothelioma and perhaps other exposure-related cancers. A cohort of some 11000 Quebec chrysotile workers, 80% of...

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Bibliographic Details
Published in:The Annals of occupational hygiene 1997-12, Vol.41 (6), p.699-705
Main Authors: McDonald, J.C., McDonald, A.D.
Format: Article
Language:English
Subjects:
Aged
Aged, 80 and over
Air pollution control
Asbestos
Asbestos, Amphibole - adverse effects
Asbestos, Serpentine - adverse effects
Biological and medical sciences
Carcinogens
Case-Control Studies
Chemical and industrial products toxicology. Toxic occupational diseases
Coal Mining
Health risks
Humans
Impurities
Inorganic dusts (pneumoconiosises) and organic dusts (byssinosis etc.)
Logistic Models
Male
Medical sciences
Mesothelioma - chemically induced
Mesothelioma - mortality
Mines
Neoplasms - chemically induced
Neoplasms - mortality
Occupational Diseases - chemically induced
Occupational Diseases - mortality
Odds Ratio
Oncology
Quebec - epidemiology
Regression analysis
Toxicology
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Summary:It has been suspected for many years that amphibole fibres in the tremolite series, a low level contaminant of chrysotile asbestos, may contribute disproportionately to the incidence of mesothelioma and perhaps other exposure-related cancers. A cohort of some 11000 Quebec chrysotile workers, 80% of whom have now died, provided the opportunity to examine this hypothesis further. An analysis was made of deaths from mesothelioma (21), cancers of the lung (262), larynx (15), stomach (99), and colon and rectum (76), in men employed by the largest company in Thetford Mines, with closely matched referents. Risks were estimated by logistic regression for these five cancers in two groups of mines—five mines located centrally and ten mines located peripherally; tremolite contamination had been demonstrated to be some four times higher in the former than in the latter. Odds ratios for work in the central mines were raised substantially and significantly for mesothelioma and lung cancer, but not for the gastric, intestinal or laryngeal cancer sites. In the peripheral mines, there was little or no evidence of increased risk for any of the five cancers. The hypothesis that, because of the difference in distribution of fibrous tremolite, cancer risks in the central area would be greater than in the periphery was thus substantiated. That the explanation may lie in the greater biopersistence of amphibole fibres than chrysotile is important in framing policies for the use and control of asbestos and is directly relevant to the selection of man-made mineral fibre substitutes.
ISSN:0003-4878
1475-3162
DOI:10.1016/S0003-4878(97)89350-7