Japan, human mercury poisoning

Minamata disease was first discovered in 1956 around Minamata Bay, Japan. A similar epidemic occurred in 1965 along the Agano river, Japan. Minamata disease is methyl mercury poisoning that occurred in humans who ingested fish contaminated with methylmercury discharged in waste water from a chemical plant. Methylmercury is also teratogenic (Ui 1992, Harada 1995, Eto 1997, Schardein 2000 see also Part III, Chapter 17). 

One of the earhest and most extensively documented cases of mercury poisoning occurred in the 1950s at Minamata Bay, in southwestern Kyushu, Japan - especially among fishermen and their famihes. Deaths and congenital birth defects in humans were attributed to long-term ingestion of marine fish and... 

Another major incident concerning methyl mercury was the severe pollution of Minamata bay in Japan (see Box 8.1). Here fish, fish-eating and scavenging birds, and humans feeding upon fish all died from organomercury poisoning. There may have been localized declines of marine species in this area due to methyl mercury, but there is no clear evidence of this. 

During the 1970s-1980s, a famous catastrophe of human poisoning by mercury and cadmium struck Japan, and this attracted anthropogenic attention to ecological and ecotoxicological problems related to heavy metals. These were uncovered to be influenced by two characteristic peculiarities of the behavior of heavy metals in the environment ... 

In one tragic incident, an entire community on Minamata Bay in Japan was poisoned, with extremely serious birth defects, very painful reactions, mental disorders, and many deaths. Only after lengthy research was the cause determined to be mercury compounds discarded into a river by a plastics factory. Whether it was inorganic salts or methylmercury compounds seems uncertain, but the contamination was immense and methylmercury compounds were found in the silt and in animals and humans. The methylmercury was readily taken up by the organisms living in the bay and, because the people of the community depended on fish and other seafood from the bay for much of their diet, the entire community was poisoned. 

Methyl mercury is toxic to humans causing CNS and peripheral nervous system injuries. 13 Those exposed suffer a degeneration of their nervous systems. Symptoms include numbness in lips and limbs, involuntary movement, constricted vision, slurred speech, and hallucinations. The most famous historic example of MeHg poisoning is the Minamata disease outbreak in Japan. 14 ... 

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