Health conditions among fishermen living in the Minamata disease prevalent area

: More than thirty years have elapsed since the major outbreak of Minamata disease. The purpose of this study is to examine the current health conditions among fishermen living along the coastal area of Yatsushiro Sea which received high exposure to methylmercury contamination. From 1988 to 1990 an interview survey was conducted on a random sample of 215 fishermen in two adjoining areas classified as contaminated: Minamata City of Kumamoto Prefecture and Izumi City of Kagoshima Prefecture. Completed responses were collected from 181 (129 males and 52 females). Health conditions were measured by four indicators: activities of daily living, presence of chronic diseases, subjective symptoms, and depressive symptoms. The associations between each health indicator and estimated intake levels of fish and/or shellfish during the heavy contamination period were examined. Residents in areas designated as contaminated can be categorized into three groups: 1) persons who are officially recognized as patients with Minamata disease, 2) persons applying for recognition as having Minamata disease but who have not been officially recognized, and 3) persons who have not applied for official recognition. In the analysis this recognition-related status was used as one of the controlling factors. Findings may be summarized as follows: 1. In both areas, a significant relationship was observed between subjective symptoms and estimated fish intake levels after controlling for sex and age. Judging from subjective symptoms, it appeared that the health level of recognized patients was lowest among the three recognition-related groups; and the health level of non-recognized persons was lower than that of the non-applicants. 2. Among Minamata City fishermen, the significant effect of fish intake levels on subjective symptoms disappeared after controlling for sex, age and recognition-related status. On the other hand, among Izumi City fishermen, a significant relationship between subjective symptoms and fish intake levels still remained by the same analysis. 3. The mental health level of the non-recognized as well as of recognized patients was comparatively lower than that of the non-applicant. However, within the limits of this study, the association between mental health and fish intake levels was not clear.