COGNITIVE DEFICIT IN 7-YEAR-OLD CHILDREN WITH PRENATAL EXPOSURE TO METHYLMERCURY

A cohort of 1022 consecutive singleton births was generated during 198 6-1987 in the Faroe Islands. Increased methylmercury exposure from mat ernal consumption of pilot whale meat was indicated by mercury concent rations in cord blood and maternal hair. At approximately 7 years of a ge, 917 of the children underwent detailed neurobehavioral examination . Neuropsychological tests included Finger Tapping; Hand-Eye Coordinat ion; reaction time on a Continuous Performance Test; Wechsler Intellig ence Scale for Children-Revised Digit Spans, Similarities, and Block D esigns; Bender Visual Motor Gestalt Test; Boston Naming Test; and Cali fornia Verbal Learning Test (Children). Clinical examination and neuro physiological testing did not reveal any clear-cut mercury-related abn ormalities. However, mercury-related neuropsychological dysfunctions w ere most pronounced in the domains of lan guage, attention, and memory , and to a lesser extent in visuospatial and motor functions. These as sociations remained after adjustment for covariates and after exclusio n of children with maternal hair mercury concentrations above 10 mu g/ g (50 nmol/g). The effects on brain function associated with prenatal methylmercury exposure therefore appear widespread, and early dysfunct ion is detectable at exposure levels currently considered safe. (C) 19 97 Elsevier Science Inc.