The Four Big Pollution Diseases of Japan were a group of manmade diseases all caused by environmental pollution due to improper handling of industrial wastes by Japanese corporations. Although some cases of these diseases occurred as early as 1912, most occurred in the 1950s, 1960s, and 1970s. Minamata disease: Mercury poisoning, 1932-68; Niigata Minamata disease: Mercury poisoning, 1965; Yokkaichi Asthma: Sulfur dioxide and nitrogen dioxide, 1961; Itai-itai disease: Cadmium poisoning,1912.
Protestors at the gates of the Chisso factory: Minamata disease is caused by severe mercury poisoning. It was first discovered in Minamata city in Kumamoto prefecture in 1956. It was caused by the release of methylmercury in the industrial wastewater from the Chisso Corporation's chemical factory, which continued from 1932 to 1968. While deaths continued for 36 years, the government and company did little to prevent the pollution. In 2004, Chisso was ordered to clean up its contamination.
Minamata disease is a neurological syndrome caused by severe mercury poisoning. 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.
W. Eugene Smith photo of mother with child suffering from severeMinamata Disease (methylmercury poisoning) on Public Health & Social Justice Website - The Social Medicine Portal--link to open access power point.