Factors Relating to the Conditions and Characteristics of Mental Health among the Inhabitants in a Methylmercury Polluted Area

Abstract

Little attention has been paid to mental health of inhabitants of methylmercury-polluted areas. The objective of this study was to examine the factors relating to the conditions and characteristics of mental health of inhabitants residing in a methylmercury-polluted area. The eligible subjects of the study were inhabitants over the age of 40 years (n=301) living in two fishing village districts that were polluted by high concentrations of methylmercury. The study was conducted in two phases. In the first phase, a structured questionnaire was used to gather information on the current health condition and experience with Minamata disease of each subject through interviews. In the second phase, the General Health Questionnaire (GHQ)-30 was distributed to measure the psychological distress of the respondents. There were 133 (44.2%) study subjects. Factor analysis of the data collected using the GHQ was carried out and five factors that accounted for 57.9% of the total variance were selected. The first factor was labeled "depression and anxiety". Depression and anxiety were significantly associated with self-rated health status, the number of subjective symptoms, monthly outpatient visits and the receipt of compensation. Covariance structure analysis using the Amos 4.0 program demonstrated that depression and anxiety were significantly associated with the subjects' health condition, which in turn was influenced by experience with Minamata disease. Depression and anxiety of the inhabitants may be directly caused by the health condition. Further investigations with more precise and detailed measurements are needed to corroborate the causal relationship.