Minamata disease, sometimes referred to as Chisso-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 fetuses . Minamata disease was first discovered in Minamata City in Kumamoto pre fecture , Japan in 1956. It was caused by the release of methylmercury in the industrial wastewater (point source pollution) from the Chisso Corporation 's chemical factory, which continued from 1932 to 1968. This highly toxic chemical bioaccumulated in shellfish and fish in Minamata Bay and the Shiranui Sea , which when eaten by the local populace resulted in mercury poisoning. While cat, dog, pig and human deaths continued ov