Fish consumption, mercury exposure, and their associations with scholastic achievement in the Seychelles Child Development Study

Abstract

Studies of neurodevelopmental outcomes in offspring exposed to MeHg from maternal consumption of fish have primarily measured cognitive abilities. Reported associations have been subtle and in both adverse and beneficial directions. Changes in functional outcomes such as school achievement and behavior in exposed children and adolescents have not been examined. We undertook an assessment of school success of children in the Seychelles Child Development Study (SCDS) Main Cohort to determine if there were any associations with either prenatal or recent postnatal MeHg exposure. The primary endpoints were Seychelles nationally standardized end-of-year examinations given when the cohort children were 9 and 17 years of age. A subgroup (n = 215) from the Main Cohort was also examined at 9 years of age using a regional achievement test called SACMEQ. Prenatal MeHg exposure was 6.8 ppm in maternal hair; recent postnatal exposure was 6.09 ppm at 9 years and 8.0 ppm at 17 years, measured in child hair. Multiple linear regression analyses showed no pattern of associations between prenatal or postnatal exposure, and either the 9- or 17-year end-of-year examination scores. For the subgroup of 215 subjects who participated in the SACMEQ test, there were significant adverse associations between examination scores and postnatal exposure, but only for males. The average postnatal exposure level in child hair for this subgroup was significantly higher than for the overall cohort. These results are consistent with our earlier studies and support the interpretation that prenatal MeHg exposure at dosages achieved by mothers consuming a diet high in fish are not associated with adverse educational measures of scholastic achievement. The adverse association of educational measures with postnatal exposure in males is intriguing, but will need to be confirmed by further studies examining factors that influence scholastic achievement.

Biomonitoring of mercury, cadmium, and lead exposure in Japanese children: a cross-sectional study

“…A cohort study of MeHg exposure in Seychelles, a country with high fish consumption similar to that in Japan, did not find any relation between postnatal mercury exposure and academic achievement in 9-year and 17-year-old children [29]. Mean hair Hg level in that study was 6.09 lg/g at 9 years and 8.0 lg/g at 17 years.…”

Seafood Intake and Neurodevelopment: A Systematic Review

“…Among 20 articles identified and fully reviewed, 3 were further excluded because they did not meet the criteria for inclusion [11][12][13]. We also excluded a randomized control trial of a fish flour bread spread because of the different nature of the exposure compared to observational studies of seafood intake [14••].…”

Background lead and mercury exposures: Psychological and behavioral problems in children

“…, proximity to a battery factory) and thereby higher Pb levels (4). In contrast, high normal metal exposures would likely occur through less clear routes and as a result of relatively minor differences in diet (5, 6), dust exposure (7), and ambient air pollution (8). More needs to be learned about possible consequences of high normal Pb exposure.…”