Relative risk of mesothelioma associated with different levels of exposure to asbestos.

The relative risk of mesothelioma associated with different levels of exposure to asbestos was evaluated. The exposure was assessed from work histories of 51 mesothelioma cases and 51 sarcoidosis referents. The lung fiber concentration of the mesothelioma patients was compared with that of two reference groups (13 random autopsy cases and 43 male lung cancer patients). When the categories definite and probable were used as an estimated probability of occupational exposure, an odds ratio of 17.7 [90% confidence interval (90% CI) 3.4-253] and 3.0 (90% CI 0.9-10.6), respectively, was obtained. A lung fiber concentration of greater than 1 million fibers/g of dry tissue as an indicator of accumulated exposure gave an odds ratio of 14.4 (90% CI 2.5-178) for the men in comparison with the autopsy cases and 3.1 (90% CI, 1.3-7.5) in comparison with the lung cancer patients. Elevated risk of mesothelioma was shown to be associated with a lung fiber concentration of greater than 1 million fibers/g of dry tissue.