Minamata’s Fight for Justice:
How Japan’s Failed Debate and Response Sparked
Local and Global Change
Investigation of Minamata Disease
Debate developed over the disease’s cause. On May 28, 1956, Minamata’s government and hospitals formed the Minamata Strange Disease Action Committee.
In November, the Kumamoto University Medical School refuted claims that the disease was infectious. Rather, they determined that it resulted from heavy metal poisoning caused by consuming local seafood, which was later confirmed by Professor Takeuchi’s July 1959 report.
"Minamata disease is a disease of the nervous system which is caused by eating fish and shellfish of the local area (Minamata Bay). Mercury has come to our attention as a likely cause of pollution of the fish and shellfish.”
~Kumamoto University Study Group's announcement, July 22, 1959, Minamata Disease Municipal Museum
Workers discarding mercury-tainted fish from Minamata Bay, 1986, Asahi Shimbun
Mercury-contamined fish from Minamata Bay, 1976, Mainichi Shimbun
Mercury content measured in organs and tissues of cats by the Kumamoto University Medical School, 1959, Water Environment Partnership in Asia
Mercury content measured in human organs (ppm wet weight) by the Kumamoto University Medical School, 1959, Water Environment Partnership in Asia
However, Chisso asserted that “the organic mercury theory of Kumamoto University [was] a speculation without actual proof" (Minamata Disease Municipal Museum), arguing that the factory had successfully used mercury since the 1930s and disputing the researchers’ credibility.
"The organic mercury theory is not only fraught with the same problems as the manganese, selenium, and thallium theories. In addition, looking at it from the view of scientific common sense, it is based on assumptions and contradicts the facts. At this stage it would be premature to immediately conclude that organic mercury is the cause of Minamata disease. Even linking it to the Minamata factory’s waste would be jumping to conclusions."
~Plant manager Nishida Eiichi at Kumamoto Prefecture’s Special Committee on Minamata Disease Countermeasures, August 5, 1959, Minamata: Pollution and the Struggle for Democracy in Postwar Japan
“Because it is a fact that the Minamata factory uses mercury as a catalyst, and that it is discharged in its effluent, we believe there is no doubt that the cause of Minamata disease is the factory’s effluent.”
Two weeks later: “At the present stage, it has not been determined that the [Chisso] factory is the cause of Minamata disease.”
~Kumamoto Nichinichi Shimbun (newspaper) before and after the Special Committee on Minamata Disease Countermeasures, August 1959, Minamata: Pollution and the Struggle for Democracy in Postwar Japan
In the early 1960s, the university identified methylmercury, isolated from the factory’s acetaldehyde process, as the disease’s causative agent.
"Minamata disease is…caused by eating fish and shellfish from Minamata Bay. The cause of intoxication is a methylmercury compound found in the shellfish, as well as in the sludge of the Chisso Minamata factory.”
~Kumamoto University Study Group, February 20, 1963, Minamata Disease Municipal Museum