Mortality rates among employees potentially exposed to chrysotile asbestos at two automotive parts factories.

A study of the mortality rates among 1657 employees at two Ontario automotive parts factories that manufactured friction materials containing chrysotile asbestos was initiated in response to the workers' concerns about the effects of asbestos on their health. A total of 1194 men and 258 women had had their first potential exposure at least 10 years before the end of the study period; 563 of the men and 138 of the women had had such an exposure at least 20 years before the end of the study period. A significantly increased rate of death from laryngeal cancer and an elevated rate of death from lung cancer were observed in a cohort analysis. One or two deaths might have been due to pleural mesothelioma. There was no increase in the rate of death from gastrointestinal cancer or from nonmalignant respiratory disease. Case-control analysis showed no association between the risk of laryngeal or lung cancer and the total duration of employment (a surrogate for the extent of ambient exposure to asbestos or other workplace toxic substances) or employment in departments where asbestos had been used. An association between risk of death and occupational exposure is uncertain.