Minamata disease is a neurological syndrome caused by severe mercury poisoning. The name corresponds to the name of the Minamata Bay in Kumamoto prefecture where the disease was first identified. During 1932-1968 local residents, especially fisher families have been suffering from a variety of symptoms. The cause (recognized in 1958) was the release of methylmercury in the industrial waste by Chisso Corporation Factory over a period of 36 years. In this sense, the disease was caused by the consumption of heavy metals which the victims ingested through contaminated fish. Fishermen demanded compensation for fishing families to damage to fishing grounds . Fishermen demanded 100.000.000 Y but they only receive 35.000.000 Y (less than 100.000 $). On 2 November 1959 the fishermen stormed the Chisso factory, destroying machinery. The riot police arrested them. The regional labour union and the citizens of Minamat sided with the Chisso company, at this point. Chisso was ready to pay some compensations but refused legal liability, until a court case was started years later.
Minamata disease symptoms include ataxia, numbness in the hands and feet, general muscle weakness, narrowing of the field of 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 foetuses in the womb. The Minamata disease was first discovered in Minamata city in 1956. It was caused by the release of methylmercury in the industrial wastewater from the Chisso Corporation's petro-chemical and plastics factory, which continued from 1932 to 1968. The company dumped an estimated 27 tons of methylmercury into the Minamata Bay over a period of 37 years. Mercury was used as a catalyst in the production of acetaldehyde, a chemical employed in the production of plastics.This highly toxic chemical bioaccumulated in Minamata Bay and the Shiranui Sea, which was then eaten by the local populace resulting in mercury poisoning.
At first doctors were unable to diagnose the cause of the disease, then in 1959, doctors at Kumamoto University determined that organic mercury poisoning was the cause of the symptoms exhibited by so many of the townspeople. Only in 1968 however did the Tokyo government acknowledge that the mercury dumping by Chisso was the ultimate cause. Five years later, Chisso admitted legal responsibility. It was proven that Chisso withheld critical information in 1959 and continued to dump waste. The government also supported the company and they were not held legally liable for their negligence until 1972. Chisso stopped production of acetaledyde in 1968--when an alternative technology for producing plastics was developed.
As of March 2001, 2,265 victims had been officially recognised (1,784 of whom had died) and over 10,000 had received financial compensation from Chisso. Over $611 million has been paid to victims in compensation [2]. In 1977, the Japanese government cleaned up the bay by vacuuming up 1.5 million cubic meters of mercury-contaminated sludge. After $359 million dollars and 14 years, the project was completed in 1997. [1] Chisso still operates in Minamata and now produces chemicals, fertilizer.
The local population has declined by 70% since its peak.
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