EXPANSION OF METHYLMERCURY POISONING OUTSIDE OF MINAMATA - AN EPIDEMIOLOGIC-STUDY ON CHRONIC METHYLMERCURY POISONING OUTSIDE OF MINAMATA

The first methylmercury poisoning by consumption of fish arose in Mina mata, Japan, in 1953. Methylmercury dispersed from Minamata to the Shi ranui Sea until 1968. Mercury concentration in the hair oi residents o n the coast of the Shiranui Sea was 10 to 20 times higher than that in nonpolluted people in Kumamoto Prefecture in 1960. People on the coas t of the Shiranui Sea have consumed fish containing low-dose methylmer cury without a ban over decades until 1968. We studied the effect of l ong-term consumption of methylmercury on those people 10 years later a fter the end of methylmercury dispersion. Our epidemiological study cl arified that people in a fishing village (Ooura) on the coast of the S hiranui Sea showed a significantly higher frequency of neurological si gns characteristic of methylmercury poisoning (hypoesthesia, ataxia, i mpairment of hearing, visual change, and dysarthria) in comparison wit h people in a nonpolluted fishing village (Ichiburi), The neurological disorders mere still detected 10 years later in Ooura after the end o f methylmercury dispersion from Minamata; hypoesthesia showed the high est frequency in Ooura, These results suggest that people on the coast of the Shiranui Sea were affected by long-term dietary exposure to me thylmercury. (C) 1995 Academic Press, Inc.