Effects of prenatal and postnatal methylmercury exposure from fish consumption on neurodevelopment: outcomes at 66 months of age in the Seychelles Child Development Study.

CONTEXT Human neurodevelopmental consequences of exposure to methyl-mercury (MeHg) from eating fish remain a question of public health concern. OBJECTIVE To study the association between MeHg exposure and the developmental outcomes of children in the Republic of Seychelles at 66 months of age. DESIGN A prospective longitudinal cohort study. PARTICIPANTS A total of 711 of 779 cohort mother-child pairs initially enrolled in the Seychelles Child Development Study in 1989. SETTING The Republic of Seychelles, an archipelago in the Indian Ocean where 85% of the population consumes ocean fish daily. MAIN OUTCOME MEASURES Prenatal and postnatal MeHg exposure and 6 age-appropriate neurodevelopmental tests: the McCarthy Scales of Children's Abilities, the Preschool Language Scale, the Woodcock-Johnson Applied Problems and Letter and Word Recognition Tests of Achievement, the Bender Gestalt test, and the Child Behavior Checklist. RESULTS The mean maternal hair total mercury level was 6.8 ppm and the mean child hair total mercury level at age 66 months was 6.5 ppm. No adverse outcomes at 66 months were associated with either prenatal or postnatal MeHg exposure. CONCLUSION In the population studied, consumption of a diet high in ocean fish appears to pose no threat to developmental outcomes through 66 months of age.