A large-scale food poisoning caused by methylmercury was identified in Minamata, Japan, in the 1950s. The severe intrauterine exposure cases are well known, although the possible impact of low-to-moderate methylmercury exposure in utero are rarely investigated. We examined neurocognitive functions among 22 participants in Minamata, mainly using an intelligence quotient test (Wechsler Adults Intelligent Scale III), in 2012/2013. The participants tended to score low on the Index score of processing speed (PS) relative to full-scale IQ, and discrepancies between PS and other scores within each participant were observed. The lower score on PS was due to deficits in digit symbol-coding and symbol search and was associated with methylmercury concentration in umbilical cords. The residents who experienced low-to-moderate methylmercury exposure including prenatal one in Minamata manifested deficits in their cognitive functions, processing speed in particular.

Original languageEnglish
Pages (from-to)297-302
Number of pages6
JournalArchives of Environmental and Occupational Health
Issue number5
Publication statusPublished - Sept 3 2015


  • Minamata disease
  • environmental pollution
  • food contamination
  • methylmercury compounds
  • neurocognitive evaluations
  • prenatal exposure delayed effects

ASJC Scopus subject areas

  • Toxicology
  • Environmental Science(all)
  • Public Health, Environmental and Occupational Health
  • Health, Toxicology and Mutagenesis


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