Malignant mesothelioma in Quebec.

All known, fatal cases of mesothelioma in the period 1960-1978 in the Province of Quebec are reviewed, because much of the world's chrysotile has been produced there and because there is also exposure to other types of asbestos. Of the 254 mesotheliomas registered, 181 were in males and 73 in females; occupational and residential histories were obtained for 91% of men and 86% of women. About 40% of male cases were probably attributable to occupational asbestos exposure; only 5.4% of females cases had been exposed occupationally. Intervals between first employment and death from mesothelioma were longer for miners and millers than for manufacturing workers: exposures of chrysotile miners and millers were mainly long and fairly low, while many factory workers had had short exposures. All tumours in miners and millers were pleural, while in factory workers, eight were peritoneal and two pleural and peritoneal. The evidence from this survey supports the view that the risk of mesothelioma after exposure to crocidolite is many times greater than that after chrysotile.