Minamata Disease from the Viewpoint of Occupational Health



Shigeru NOMURA, et al

Department of Public Health, Kumamoto University School of Medicine

Minamata disease, Methyl mercury poisoning, Environmental health hazards, Occupational disease
M. Futatsuka, Department of Public health, Kumamoto University School of Medicine, 2-2-1 Honjo, Kumamoto 860, Japan
J Occup Healthyear1998Vol40No11-8

Minamata disease is a neurological disorder caused by methyl mercury poisoning which occurred as the result of ingestion of large quantities of fish and shellfish polluted by industrial waste water in Minamata and Niigata, Japan. More than 40 years have passed since the epidemic was first reported in 1956 in Minamata. Inorganic mercury used as a catalyst in the acetaldehyde process had methylated inside the factory and had then been discharged into Minamata Bay. The waste from the acetaldehyde process continued to pour into the bay until 1968. In the process of researching possible causal elements, the Minamata Disease study Group of the Kumamoto University School of Medicine found that the clinical and pathological findings in eases of Minamata disease coincided with certain cases of methyl mercury poisoning in England reported in 1940 by D. Hunter and D.S. Russell and which were published in a monograph on occupational toxicology in 1958. The English cases involved the poisoning of workers in a factory producing methyl mercury pesticide. It is clear that occupational poisoning can provide an important guide for the investigation into the cause of an environmental disease such as Minamata disease but there are differences between the two types of poisoning as they occur under different conditions. Occupational poisoning is a direct poisoning of workers, which occurs under certain conditions, whereas Minamata disease involves the poisoning of the entire population of a contaminated area, including embryos, the aged and those who are already suffering from other diseases. When these points are considered, it becomes clear that although Minamata disease and occupational poisoning coincide with each other in some respects, they do not in others.