Minamata Disease: The History and Measures
Environmental Health Department, Ministry of the Environment, 2002
Minamata Disease, which is a typical example of the pollution-related health damage in Japan, was first discovered in 1956, around Minamata Bay in Kumamoto Prefecture, and in 1965, in the Agano River basin in Niigata Prefecture. Since the discovery of the disease, investigation of the cause has been made, and finally in 1968, the government announced its opinion that Minamata Disease was caused by the consumption of fish and shellfish contaminated by methylmercury compound discharged from a chemical plant.
It is known that Minamata Disease is a disorder of the central nervous system and shows various signs and symptoms including sensory disturbance in the distal portions of four extremities, ataxia, concentric contraction of the visual field, etc. At the end of March 2001, 2,955 Minamata Disease patients have been certified, of which 2,265 patients have been located on Yatsushiro Sea coast.
Due to the clinical and protective measures taken after the discovery of the disease, Minamata Disease no longer seems to occur in Japan.
As measures against the environmental pollution, maximum efforts to improve of the environmental pollution have also been made; removal of the contaminated sediments of the bay and the river floor, monitoring of methylmercury levels in fish and wastewater, and so on.
With regard to relief of the victims, a large-scale survey of health damage was carried out in order to grasp the extent of health damage. The structure is set up, that the government certifies persons as Minamata Disease based on Pollution-related Health Damage Compensation Law, and those who are recognized as Minamata Disease from the point of view of medical science can receive compensation from the company which is responsible for the pollution. (A lump-sum payment of about 22,000,000 yen had been paid to each of 2,955 certified patients on average, and the total payment amounts to approximately 144 billion yen by March 2001.) And furthermore, from fiscal year of 1992, in order to get rid of the worry in health which is felt by people who might have been exposed to methylmercury, the government does medical examinations to the area inhabitants and assists financially medical expense of one who has signs and symptoms resembled Minamata Disease, and so on.
In addition, the government has financed the responsible company to assist in payment of enormous compensation and promoted research and investigation about Minamata Disease, one of which was the establishment of the National Institute for Minamata Disease.
Like this, the case of Minamata Disease in Japan makes it clear that activities which give priority to economic goals but lack proper attention to the environment cause irreparable damages and bring undesirable results even from an economic point of view as well, since so many measures, huge costs and a long time period are required against these damages.
We hope that it will be realized again how consideration of environment is important and the efforts will be made to prevent environmental pollution in other countries having such experience in Japan as a lesson.
