Contents - Previous - Next

This is the old United Nations University website. Visit the new site at


1. In 1965 a similar, but less well known, example of methyl mercury poisoning was recognized near a Showa Denko KK. industrial plant in the Agano River basin of Niigata Prefecture.

2. Although the facts reported here are not contested by most analysts, other writers have emphasized different aspects of the Minamata disease disaster. Apart from general overviews, the English-language literature on Minamata is relatively sparse; see Ui (1992) and Ellis (1989).

3. Rulings are made on individual cases by a medical board of inquiry that examines the results of examinations conducted by prefectural authorities.

4. The sludge accumulated in Minamata Bay contained a high concentration of mercury. In 1987, sludge was dredged and used to fill in the distal part of the bay with the intention of covering over 209 m of sea bottom that contains mercury in concentrations of 25 ppm or more. Residents were alarmed that further contamination might be triggered by this action. They opposed the plan but it went ahead anyway and was completed in 1990, 14 years after initiation, at a cost of 48.5 billion. Nevertheless, fish and shellfish in the bay continue to exceed the provisional pollution control level stipulated by the national government (i.e. total mercury < 0.44 ppm; methyl mercury < 0.3 ppm). There is no sign that the ban on fishing in the bay will soon be raised.

5. The mimaikin contract was later annulled in legal proceedings that found Chisso guilty of violating public order and morale by "deliberately neglecting their responsibility to respond to the victims' proper and just claims for reparations, for further taking advantage of the ignorance and oppressed financial state of the victims' families and for tendering retribution in an extremely low sum." (Verdict from the First Lawsuit against Chisso, 1973.)

6. The syndrome is named after two investigators of methyl mercury poisoning at an agrochemical factory in England. Their work provided important clues about the cause of Minamata disease.


Chisso. 1955. Minamata Plant Newsletter, September.

Ellis, Derek. 1989. Environments at Risk: Case Histories of Impact Assessment. Berlin: Springer-Verlag, pp. 38-69.

Funaba, Masatomi. 1973. "Chisso and the community and municipality." Research into Industrial Pollution 2(4).

Nakamura, Masafumi. 1975. "Structure and features of Chisso's local dominance in Minamata." In: Kenji Kono, ed. Transfiguration of the Local Community and Resident Sentiment.

Ui, Jun. 1992. "Minamata disease." In: Jun Ui, ed. Industrial Pollution in Japan. Tokyo: United Nations University Press, pp. 103-132.

Contents - Previous - Next