No cases of human poisoning by alkylmercury compounds in intended foodstuffs have been reported in North America to date.1 However, its symptoms are well known, from accidental poisonings and the tragic episodes at Minamata and Niigata, Japan. The chief culprit has been methylmercury. Summarized, these symptoms include, more or less in order of ascending severity, (a) excessive weakness, fatigue, apathy, lack of interest; (b) paresthesias of perioral area and extremities; (c) "tunnel vision," hearing difficulties, fits of rage, depression; (d) dysarthria, dysdiadochokinesia, ataxia, alexia, agraphia, clumsiness in handling familiar objects, intention tremor; (e) gross motor incoordination, spasticity, paralysis, coma, death.
Minamata disease, first reported in Japan in 1953, affected 121 persons, causing 46 deaths. Its origin was methylmercury chloride, discharged into the Minamata Bay and River by a plastics plant; fish containing 20