Update:April 1, 2010

(5) Administrative Measures by the National Government, Kumamoto prefecture, and Minamata City

2.Mercury Poisoning and Control Responses

In January 1959, the Ministry of Health and Welfare organized the Special Task Group of the Food and Sanitation Investigation Committee and launched an investigation into the cause of Minamata Disease, They reported to the Minister of Health and Welfare in November that organic mercury compound was responsible for the disease.
The Ministry of International Trade and Industry then directed Chisso in October 1959 to stop discharging waste water from Hachiman Pool immediately and now them back to Hyakken port and to complete the waste water purification plant by the end of the year.
Subsequently, the national government started imposing methylmercury discharge control on all plants and factories releasing their industrial waste water into Minamata Bay in 1969. Also, in 1970, they enacted the Water Pollution Prevention Act to restrict the discharge of poisonous substances such as mercury and cadmium upon all water areas in Japan.
Together with the above, the Ministry of International Trade and Industry has advised not only Chisso and Showa Denko K.K. but other caustic soda (sodium hydroxide) plants to change their manufacturing processes if their discharge is likely to contain mercury.
Later, in 1971, Kumamoto University started a full-scale health survey on 110,000 residents in the vicinity of Minamata Bay.
In 1974, Minamata City and Chisso signed a Pollution Control Agreement. In 1978, the Environment Agency established the National Institute for Minamata Disease to conduct clinical studies and comprehensive research and survey for the development of the treatment method for the disease. The institute was designated by the World Health Organization as the cooperation center related to the study on the impact of mercury on human health and has been dedicated itself to environmental protection on a global basis.