Minamata Disease — Mercury Poisoning and the Fight for Recognition (1956–2013)

Physicians led by Hajime Hosokawa at the Chisso Corporation's factory hospital reported an epidemic of an unknown disease of the central nervous system, beginning with two young girls who suffered convulsions, loss of consciousness, and involuntary movement. Dozens of similar cases were soon identified among fishing families who ate fish and shellfish from Minamata Bay.

Location: Minamata, Kumamoto Prefecture, Japan

After investigations uncovered heavy mercury contamination of Minamata Bay in February 1959, Japan's Ministry of Health and Welfare reported that Minamata disease was a poisoning caused by consuming fish and shellfish from the bay, "the major causative agent being some sort of organic mercury compound." Chisso continued to deny responsibility and wastewater discharge continued.

Location: Tokyo and Minamata, Japan

A second outbreak of mercury poisoning, later named Niigata Minamata disease, was made public among residents downstream of the Showa Denko chemical plant on the Agano River. The repeat outbreak showed that the problem belonged to Japan's postwar chemical industry as a whole, and it triggered a new wave of lawsuits.

Location: Niigata Prefecture, Japan

The national government issued its official conclusion that Minamata disease was caused by methylmercury wastewater from Chisso's acetaldehyde plant and that Niigata Minamata disease was caused by Showa Denko. The finding came twelve years after the disease was first reported, following years in which the company disputed causation and authorities delayed acknowledgment.

Location: Japan

The Litigation Group of the Minamata Disease Patients Families Mutual Aid Society filed a damages suit against Chisso in the Kumamoto District Court, following the Niigata patients who had sued Showa Denko in 1968. The plaintiffs argued the company had known of the poisoning and continued discharging wastewater, while Chisso maintained its conduct had not been proven to cause the disease.

Location: Kumamoto, Japan

The Kumamoto District Court found Chisso negligent and ordered the company to pay damages to the Litigation Group patients, the first judgment to hold it legally responsible for the poisoning. A parallel appellate process produced a mediated settlement the same year, but the Kansai patients' association rejected it and continued litigating until the Supreme Court affirmed their victory in 2004.

Location: Kumamoto, Japan

Photographers W. Eugene Smith and Aileen Smith published the book Minamata: The Victims and Their World, including the image "Tomoko Uemura in Her Bath," which showed a congenitally poisoned girl being bathed by her mother. The book brought international attention to industrial mercury poisoning and became one of the defining works of environmental photojournalism.

Location: Minamata, Japan

The Supreme Court of Japan ruled that the national government and Kumamoto Prefecture were responsible for failing to prevent the spread of Minamata disease after 1960, when the cause had become scientifically plausible, and ordered compensation for plaintiffs who had been denied official certification. The ruling placed part of the liability on the state that failed to act, not only on the polluter.

Location: Tokyo, Japan

The Japanese government, Kumamoto Prefecture, and Chisso agreed to a settlement providing relief to thousands of people who had never been officially certified as victims, ending decades of dispute over restrictive recognition criteria. By then some 2,265 people had been certified and more than 10,000 had received compensation of some kind.

Location: Japan

Governments adopted the Minamata Convention on Mercury, a global treaty to protect human health and the environment from mercury emissions and releases, named after the city whose poisoning came to symbolize industrial pollution. The convention entered into force in 2017 and governs mercury use, trade, and disposal internationally.

Location: Kumamoto, Japan