Minamata disease is a neurological disease caused by severe mercury poisoning. Signs and symptoms include ataxia, numbness in the hands and feet, general muscle weakness, loss of peripheral vision, and damage to hearing and speech. In extreme cases, insanity, paralysis, coma, and death follow within weeks of the onset of symptoms. A congenital form of the disease can also affect fetuses in the womb and may cause cerebral palsy. Minamata disease was first discovered in the city of Minamata, Kumamoto Prefecture, Japan, in 1956, hence its name. It was caused by the release of methylmercury in the industrial wastewater from a chemical factory owned by the Chisso Corporation, which continued from 1932 to 1968. It has also been suggested that some of the mercury sulfate in the wastewater was also metabolized to methylmercury by bacteria in the sediment. This highly toxic chemical bioaccumulated and biomagnified in shellfish and fish in Minamata Bay and the Shiranui Sea, which, when eaten by the local population, resulted in mercury poisoning. While cat, dog, pig, and human deaths continued for 36 years, Chisso and the Kumamoto prefectural government did little to prevent the epidemic. The animal effects were severe enough in cats that they came to be named as having "dancing cat fever".As of March 2001, 2,265 victims had been officially recognized as having Minamata disease and over 10,000 had received financial compensation from Chisso. By 2004, Chisso had paid US$86 million in compensation, and in the same year was ordered to clean up its contamination.
The total compensation of ¥937 million ($3.4 million) was the largest sum ever awarded by a Japanese court. Uncertified patients fight to be recognised
While the struggles of the arbitration and litigation groups against Chisso were continuing, a new group of individuals with Minamata disease emerged. To qualify for compensation under the 1959 agreement, patients had to be officially recognised by various ad hoc certification committees according to their symptoms. However, in an effort to limit the liability and financial burden on the company, these committees were sticking to a rigid interpretation of Minamata disease. They required that patients must exhibit all symptoms of Hunter-Russell syndrome – the standard diagnosis of organic mercury poisoning at the time, which originated from an industrial accident in the United Kingdom in 1940. The committee certified only patients exhibiting explicit symptoms of the British syndrome, rather than basing their diagnosis on the disease in Japan. This resulted in many applicants being rejected by the committee, leaving them confused and frustrated. Legacies
Epidemiology
As of March 2001, 2,265 victims had been officially certified and over 10,000 people had received financial compensation from Chisso, although they were not recognised as official victims. The issue of quantifying the impact of Minamata disease is complicated, as a full epidemiological study has never been conducted and patients were recognised only if they voluntarily applied to a certification council to seek financial compensation. Many individuals with Minamata disease faced discrimination and ostracism from the local community if they came out into the open about their symptoms.