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In 1908 Chisso Corporation begins producing chemical fertilizers in Minamata village, Japan
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By 1932 Chisso had begun manufacturing acetaldehyde, a raw material of plastic. When this is produced, highly toxic methyl mercury is generated. The methyl mercury flowed into the sea with discharged water, and sludge containing a large amount of mercury accumulated at the bottom of the sea
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In 1950 shellfish started to die as well as fish with their bellies up, and seaweed stopped growing
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From 1954, many cats died and birds fell out of the sky. At homes in which fish was mixed with the feed and given to chickens and pigs, domestic animals went mad and died
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The director of SNC Hospital reports to the Minamata Public Health Center on an influx of patients with similar nervous system damage symptoms.
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The Kumamoto University Study Group makes its public official report concerning the causes of Minamata disease: "... causative agents of Minamata disease are methyl mercury compound extracted from shellfish caught in the bay and taken from sludge from the SNC plant. However, the extracted substances are slightly different in structure."
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In 1968, Minamata disease was finally recognized by the government as a pollution disease caused by methylmercury discharged from the Chisso Minamata Factory
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In 1968, Chisso Corporation finally stopped discharging mercury
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In 1977, Kumamoto Prefecture began construction of a landfill for the sludge containing mercury and sealed it off.
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In 1997, Kumamoto Prefecture issued a declaration of safety for Minamata Bay. As a result, currently Minamata Bay is one of the cleanest seas with high water clarity and low degree of contamination.
