Article

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

University of Rochester, School of Medicine and Dentistry, Department of Pediatrics, Rochester, NY 14642, USA.
NeuroToxicology (Impact Factor: 3.38). 09/2010; 31(5):439-47. DOI: 10.1016/j.neuro.2010.05.010
Source: PubMed

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.

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    • "In mammals, MeHg is a strong neurotoxicant, particularly affecting the developing nervous system, and has been associated with neurological problems (Davidson et al., 2010). The cytotoxicity of MeHg has been attributed to disturbance of intracellular Ca 2+ levels, induction of oxidative stress or by disrupting function of proteins and peptides containing cysteine and methionine (Ceccatelli et al., 2010). "
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    • "Longitudinal exposure to mercury was also evaluated in the Seychelles cohort. Mercury was analysed in hair samples from the prenatal period (maternal hair) to age 9 and 17 years (Davidson et al., 2010). A slight decreasing trend was observed from birth (6.8 ppm) to age 9 (6.09 "
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    • "In some studies boys seem to be more affected (Grandjean et al. 1998, Gao et al. 2007, Davidson et al. 2010), in others girls (Davidson et al. 1998, 2008). There are similar results of experimental studies on laboratory animals exposed to mercury. "

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