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Mortality among 535 asbestos-exposed and 205 nonexposed employees of an asbestos-cement factory was investigated. In the period beyond 20 yr from first exposure, the exposed workers had standardized mortality ratios of 175 for all causes of death, 370 for all malignancies, 480 for lung cancer, 240 for gastrointestinal cancers, and 17 deaths from mesothelioma; the factory control subjects had mortality rates similar to the general population. The cell-type distribution of the lung cancers was similar to that occurring in middle-aged smokers. Cumulative fiber exposures were calculated for the production workers, and mortality rates for the asbestos-associated malignancies were found to have significant trends with exposure. Exposure-related lung cancer risks were noted, with a large margin of uncertainty, to be similar to those observed in an American study of manmade mineral fiber workers.

We studied the development of small irregular opacities and bilateral pleural thickening in a longitudinal study of 181 asbestos-cement workers. The relationships between the 32-yr risks of developing abnormalities and cumulative exposure to asbestos dust could be described with log-normal curves. Smokers had higher risks of both abnormalities than did nonsmokers. In this cohort, men leaving asbestos exposure had a risk of radiographic progression similar to men continuing in exposure, and men with abnormal radiographs had higher mortality rates than did men with normal ones.

We studied the development of compensable (certified) asbestosis among the 201 workers at an asbestos-cement factory who were first exposed to asbestos dust prior to 1980 and who had been employed at least 15 yr. By July 1980, 39% of the production workers and 20% of the maintenance workers had developed a compensable chest disability; the "latent interval" generally exceeded 20 yr. Workers with asbestosis were found to have markedly elevated mortality rates with deaths caused by malignancies and respiratory disease being primarily responsible. We combined the limited air sampling data available with individual work histories to calculate 18-yr cumulative fiber exposures. The cumulative probability of certification was related to the cumulative exposures and the exposure-response relationship was found to be sigmoidal in form.