Health Surveillance in the Population Living in a Methyl Mercury-Polluted Area over a Long Period

• Published in: Environmental research 2000-06, Vol.83 (2), p.83-92
• Main Authors: Futatsuka, Makoto, Kitano, Takao, Shono, Masahiro, Fukuda, Yoshiharu, Ushijima, Kayo, Inaoka, Tsukasa, Nagano, Megumi, Wakamiya, Junji, Miyamoto, Kenjiro
• Format: Article
• Language: English
• Subjects: Aged; Biological and medical sciences; Chemical and Drug Induced Liver Injury; Diabetes Mellitus - chemically induced; Diabetes Mellitus - epidemiology; dimethylmercury; Environmental Monitoring; Environmental Pollutants - adverse effects; Environmental pollutants toxicology; Epidemiological Monitoring; Female; Follow-Up Studies; General aspects; Health Status; health surveillance: population survey; Humans; Incidence; Japan; Japan - epidemiology; Kidney Diseases - chemically induced; Kidney Diseases - epidemiology; Liver Diseases - epidemiology; Male; Medical sciences; methyl mercury; Methylmercury Compounds - adverse effects; Middle Aged; Minamata disease; neurological complications; population studies; Population Surveillance; Risk Factors; Toxicology
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1006/enrs.1999.4014

It is important to follow up on the health status of inhabitants living in the methyl mercury-polluted area surrounding Minamata City, paying particular attention to diseases not only of the central nervous system but also of other organs. We have been carrying out such concentric studies for more than 10 years. We have previously studied the cause-specific standard mortality ratios in Minamata disease patients and reported that the SMRs for liver disease and renal disease were significantly raised in male and female patients, respectively. It was also found that complications arising from diabetes could be due to the large number of old people among the autopsy cases. The next step was to clarify the actual prevalence and incidence of liver disease, renal disease, and diabetes mellitus epidemiologically among the population in this area. The aim of this study was to determine the actual prevalence of these diseases and complaints, and to investigate the contribution of various risk factors to these diseases in this area. The study was a population-based cross-sectional mass screening survey. A case-control study was designed to estimate the role of various risk factors including methyl mercury exposure for these diseases. A mass multiple health examination survey was performed in 1500 subjects aged 40 years and older in Tsunagi Town, neighboring Minamata City, every summer since 1984. Tsunagi Town is located in a methyl mercury-polluted area and there are 36.9 certified Minamata disease patients per 1000 population. Data concerning liver disease, renal disease, and diabetes mellitus were collected on the basis of urine, hematological, physical, and ultrasonographic examinations. Data on risk factors and subjective complaints were collected by interview and other measures. The prevalence of these diseases was not higher in this methyl mercury-polluted area compared with other areas in Japan, contrary to what was expected based on standard mortality ratios and pathological findings. There were no positive correlations between those diseases and methyl mercury exposure. On the other hand, the population in the polluted area had more and a greater variety of complaints than those in the nonpolluted area. 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 methyl mercury exposure. This health surveillance in the population living in a methyl mercury-p