Clinical observations following asbestos exposure.

There is a spectrum of clinical entities following occupational exposure to asbestos. Methods of evaluation for these problems are reviewed. Nonmalignant clinical conditions include asbestos warts, asbestos bodies, parenchymal fibrosis (asbestosis), pleural fibrosis and calcification, and benign asbestotic pleural effusion. Asbestosis, though a benign process, is a significant cause of death. Malignant conditions associated with asbestos exposure include lung cancer, accounting for about 20% of all deaths among insulation workers and significantly related to cigarette smoking. The lung cancers tend to occur more frequently in the lower lobes and are more peripheral. Pleural and peritoneal mesothelioma and some excesses in gastrointestinal cancers are found with asbestos exposure, although these are not related to cigarette smoking. Increased rates of malignancy first become significant after 20 years from onset of exposure and are also related to duration of exposure. Difficulties with the use of death certificate data are reviewed.