An analysis of subjective complaints in a population living in a methylmercury-polluted area

The aim of this study is to document subjective complaints, to analyze the structure of a population living in a methylmercury-polluted area, and to investigate the relationship between the subjective complaints and methylmercury pollution. A total of 1304 adults in the polluted area, who were living in the methylmercury-polluted area near Minamata City in Kumamoto Prefecture, Japan, and 446 age-matched adults in a nonpolluted area were interviewed. Comparison of prevalence, factor analysis, and cluster analysis were conducted using data drawn from a questionnaire survey about 64 subjective complaints. The population in the polluted area had more various complaints than that living in the nonpolluted area. The factor analysis proposed four factors: nonspecific, sensory, arthritic, and muscular. Each of the four factor scores was significantly higher in the population in the polluted area. Subjects who had more complaints were classified into three clusters using cluster analysis. It is possible that not only neurological subjective complaints but also nonspecific complaints of the population in the polluted area might be influenced by past methylmercury exposure.