LONGITUDINAL NEURODEVELOPMENTAL STUDY OF SEYCHELLOIS CHILDREN FOLLOWING IN-UTERO EXPOSURE TO METHYLMERCURY FROM MATERNAL FISH INGESTION - OUTCOMES AT 19 AND 29 MONTHS

Despite the importance of defining developmental consequences for huma ns of in utero exposure to low levels of methylmercury, it is not yet clear if there are postnatal effects in fish-eating populations. The S eychelles Child Development Study (SCDS) now underway in the Republic of Seychelles, is following children to test the hypothesis that prena tal exposure to low concentrations of MeHg through maternal ingestion of fish is related to child development outcomes. In this study, child ren were evaluated with the Bayley Scales of Infant Development (BSID) at 19 mos. of age (N = 738). The cohort was evaluated again at 29 mos . (N = 736) with the BSID and the Bayley Infant Behavior Record. Mercu ry exposure determined by cold vapor atomic absorption analysis of mat ernal hair segments corresponding to pregnancy revealed a median expos ure of 5.9 ppm (Range 0.5 - 26.7 ppm). The association between materna l hair mercury concentrations and neurodevelopmental outcomes at 19 an d 29 mo. of age was examined by multiple regression analysis with adju stment for confounding variables. Results: BSID Intertester reliabilit y was ascertained by the Kappa statistic and was high. The mean BSID M ental Sea le Indexes at both 19 and 29 mo. were comparable to the mean performance of US children. The mean BSID Psychomotor Scale Indexes a t 19 and 29 mo. were 2 SD units above US norms, but consistent with pr evious findings of motoric precocity in children reared in African cou ntries. No effect of mercury was detected on BSID scores at either age . On the Bayley Infant Behavior Record, activity level in boys, but no t girls, decreased with increasing mercury exposure. Only one subjecti ve endpoint was correlated with prenatal exposure to mercury. This stu dy may have implications for environmental health policies concerning mercury in fish or fish consumption during pregnancy. Follow-up data a re needed to determine if adverse effects occur at older ages and if s uch effects are determined to be related to mercury. (C) 1995 Intox Pr ess, Inc.