[Twenty years' follow-up study of asbestos workers]

This report describes a cohort study conducted on workers who were employed in a factory mainly manufacturing asbestos yarn and cloth and were followed from 1964 to 1981. A total of 208 workers (73 males and 135 females) could be traced and 15 deaths were observed by the end of 1983. Among them, three had lung cancer and its relative risk was 6.8 (p less than 0.05) computed based on the age, sex and year specific death rates of Osaka Prefecture. One case of peritoneal mesothelioma was also found. The period from first asbestos exposure to death of these four cases of asbestos-related malignancies was more than 25 yr. In the analysis of the employees who had more than 1 yr of exposure to asbestos and those who had already been engaged in this factory at the beginning of the observation, the relative risk of lung cancer was 8.1 and 13.6, respectively.