Indications of an increase of occupational pleural mesothelioma in Japan.

In order to obtain an epidemiological picture of occupational pleural malignant mesotheliomas in Japan, the author surveyed the Annual of Pathological Autopsy Cases (published by the Japanese Pathological Society) from 1974 through 1980. Two hundred and twenty-two malignant mesotheliomas (0.114% of all autopsy cases) were found in that period. One hundred and forty-five cases (0.074%) of them were of pleural origin. Until 1977, there were no pleural malignant mesotheliomas associated with asbestosis, but there were one in 1978, three in 1979 and two in 1980. Two of them were housewives and the others were a ship builder, a welder, a ceramist and a steel factory worker. Two lived in Sakae City, and the others in Kure City, Kaizuka City, Nagasaki City and Kanagawa Prefecture, where large shipyards are located. Compared to the Western countries, there is a time lag of 10 to 20 years in the increase of consumption of asbestos in Japan, where the increase has occurred rapidly after World War II. The epidemiological picture obtained by this study clearly states that the number of occupational pleural malignant mesotheliomas began to increase in the past few years in Japan.