Relation of Prenatal Methylmercury Exposure from Environmental Sources to Childhood IQ

Overview

Journal Environ Health Perspect

Date 2015 Mar 11

PMID 25757069

Citations 40

Authors

Joseph L Jacobson

Gina Muckle

Pierre Ayotte

Eric Dewailly

Sandra W Jacobson

Affiliations

Soon will be listed here.

Abstract

Background: Although prenatal methylmercury exposure has been linked to poorer intellectual function in several studies, data from two major prospective, longitudinal studies yielded contradictory results. Associations with cognitive deficits were reported in a Faroe Islands cohort, but few were found in a study in the Seychelles Islands. It has been suggested that co-exposure to another contaminant, polychlorinated biphenyls (PCBs), may be responsible for the positive findings in the former study and that co-exposure to nutrients in methylmercury-contaminated fish may have obscured and/or protected against adverse effects in the latter.

Objectives: We aimed to determine the degree to which co-exposure to PCBs may account for the adverse effects of methylmercury and the degree to which co-exposure to docosahexaenoic acid (DHA) may obscure these effects in a sample of Inuit children in Arctic Québec.

Methods: IQ was estimated in 282 school-age children from whom umbilical cord blood samples had been obtained and analyzed for mercury and other environmental exposures.

Results: Prenatal mercury exposure was related to poorer estimated IQ after adjustment for potential confounding variables. The entry of DHA into the model significantly strengthened the association with mercury, supporting the hypothesis that beneficial effects from DHA intake can obscure adverse effects of mercury exposure. Children with cord mercury ≥ 7.5 μg/L were four times as likely to have an IQ score < 80, the clinical cut-off for borderline intellectual disability. Co-exposure to PCBs did not alter the association of mercury with IQ.

Conclusions: To our knowledge, this is the first study to document an association of prenatal mercury exposure with poorer performance on a school-age assessment of IQ, a measure whose relevance for occupational success in adulthood is well established. This association was seen at levels in the range within which many U.S. children of Asian-American background are exposed.

Citing Articles

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Methylmercury Induces Apoptosis in Mouse C17.2 Neural Stem Cells through the Induction of OSGIN1 Expression by NRF2.

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Pre- and postnatal exposure to legacy environmental contaminants and sensation seeking in Inuit adolescents from Nunavik.

Gagnon-Chauvin A, Jacobson S, Jacobson J, Fornasier-Belanger M, Courtemanche Y, Ayotte P PLOS Glob Public Health. 2023; 3(10):e0002478.

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Postnatal methylmercury exposure and neurodevelopmental outcomes at 7 years of age in the Seychelles Child Development Study Nutrition Cohort 2.

Klus J, Thurston S, Myers G, Watson G, Rand M, Love T Neurotoxicology. 2023; 99:115-119.

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Mergler D, Philibert A, Fillion M, Da Silva J Environ Health Perspect. 2023; 131(7):77001.

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