Methyl Mercury Exposure at Niigata, Japan: Results of Neurological Examinations of 103 Adults. (25th July 2012)

• Record Type: Journal Article
• Authors: Maruyama, Kimio; Yorifuji, Takashi; Tsuda, Toshihide; Sekikawa, Tomoko; Nakadaira, Hiroto; Saito, Hisashi
• Other Names: Dorea Jose G. Academic Editor.
• Is Part Of: Journal of biomedicine and biotechnology. Volume 2012(2012)
• Publication Date: 2012-07-25
• Subjects: Medicine -- Periodicals; Biology -- Periodicals; Biotechnology -- Periodicals; Medicine; Biology; Biotechnology; Médecine; Biologie; Biotechnologie; Biology; Biotechnology; Medicine; Biotechnology; Biomedicine; Electronic journals; Periodical; Periodicals; Electronic journals; 610
• DOI: 10.1155/2012/635075
• Languages: English
• ISSNs: 1110-7243

Abstract

Abstract : Background . Large-scale poisonings caused by methyl mercury (MeHg) have occurred in Japan (Minamata in the 1950s and Niigata in the 1960s) and Iraq (in the 1970s). The current WHO neurological risk standard for adult exposure (hair level: 50 μ g/g) was based partly on evidence from Niigata which did not consider any cases who were diagnosed later and/or exposed to low level of MeHg (hair mercury level less than 50 μ g/g). Methods . Early in the Niigata epidemic in June 1965 there were two extensive surveys. From these two surveys, we examined 103 adults with hair mercury measurement who consulted two medical institutions. We compared the prevalence and the distribution of neurological signs related to MeHg poisoning between exposure categories. Result . We found 48 subjects with neurological signs related to MeHg poisoning who had hair mercury concentration less than 50 μ g/g. Among the neurological signs, sensory disturbance of the bilateral distal extremities was observed more frequently, followed by disequilibrium, hearing impairment, and ataxia, in groups with hair MeHg concentration both below 50 μ g/g and over 50 μ g/g. Conclusion . The present study suggests the possibility that exposure to MeHg at levels below the current WHO limits could cause neurologic signs, in particular, sensory disturbance.