肺内石綿繊維からみた石綿関連疾患

Abstract

An increase in the number of patients with asbestos-related diseases was manifested by analysis of autopsy cases registered in the Annual of the Pathological Autopsy Cases in Japan (by the Japanese Society of Pathology), and the increase incidence implies that health hazard due to asbestos exposure has extended to asbestos workers and some residents in Japan. Asbestos body counts in the lungs of autopsies performed at random of 235 patients revealed that the positive rate was 97.4%. Pollution by asbestos has widely affected the residents in Japan. In addition, from the counts of asbestos bodies in asbestos-related diseases, approximately a half of malignant mesothelioma and 10% of lung cancer patients has been received an occupational asbestos exposure. In our selected asbestos-related diseases, mainly amosite and crocidolite were found in the lungs. The long fibers with a high aspect ratio were frequently found to be amosite fibers. Among crocidolite fibers, thin fibers with a high aspect ratio were also found frequently. It is thought that such size in both fibers has biologically strong effects. Asbestos bodies were frequently formed in long fibers with a high aspect ratio, and it means that their counts evaluate harmful fibers. Therefore, the evaluation of asbestos body counts is a good indicator for asbestos exposure. It almost relies on the import for the use of asbestos in Japan, and an amount of the import was about 300000 tons until 1990. The latent period of the asbestos-related diseases is 20-40 year. Therefore, an increase of the patients with asbestos-related diseases will be worried in the future.