Article

Postnatal exposure to methyl mercury from fish consumption: A review and new data from the Seychelles Child Development Study

University of Rochester School of Medicine and Dentistry, Department of Neurology, Rochester, NY, United States.
NeuroToxicology (Impact Factor: 3.05). 06/2009; 30(3):338-49. DOI: 10.1016/j.neuro.2009.01.005
Source: PubMed

ABSTRACT Fish is an important source of nutrition worldwide. Fish contain both the neurotoxin methyl mercury (MeHg) and nutrients important for brain development. The developing brain appears to be most sensitive to MeHg toxicity and mothers who consume fish during pregnancy expose their fetus prenatally. Although brain development is most dramatic during fetal life, it continues for years postnatally and additional exposure can occur when a mother breast feeds or the child consumes fish. This raises the possibility that MeHg might influence brain development after birth and thus adversely affect children's developmental outcomes. We reviewed postnatal MeHg exposure and the associations that have been published to determine the issues associated with it and then carried out a series of analyses involving alternative metrics of postnatal MeHg exposure in the Seychelles Child Development Study (SCDS) Main Cohort.
The SCDS is a prospective longitudinal evaluation of prenatal MeHg exposure from fish consumption. The Main Cohort includes 779 subjects on whom recent postnatal exposure data were collected at the 6-, 19-, 29-, 66-, and 107-month evaluations. We examined the association of recent postnatal MeHg exposure with multiple 66- and 107-month outcomes and then used three types of alternative postnatal exposure metrics to examine their association with the children's intelligence quotient (IQ) at 107 months of age.
Recent postnatal exposure at 107 months of age was adversely associated with four endpoints, three in females only. One alternative postnatal metric was beneficially associated with 9-year IQ in males only.
We found several associations between postnatal MeHg biomarkers and children's developmental endpoints. However, as has been the case with prenatal MeHg exposure in the SCDS Main Cohort study, no consistent pattern of associations emerged to support a causal relationship.

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    • "The data we reported upon here from the ELEMENT cohort may have an important role in the global effort to understand the public health risks of mercury, especially methylmercury exposure from seafood. To date, decisions have mainly relied upon data from two longitudinal birth cohort studies in the Faroe Islands and Seychelles which address neuropsychological outcomes in relation to current, early-life, and developmental exposures to methylmercury and fish consumption (Davidson et al., 2006; Debes et al., 2006; Myers et al., 2009). The studies differ in many regards (e.g., exposure biomarkers, neurodevelopmental tests, timing of tests, co-stressors, participant diet). "
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    • "Examples include inhalation of Hg vapor from atmospheric sources or from dental amalgam fillings, and, most importantly, ingestion of fish and shellfish contaminated with Hg, primarily methyl Hg (U.S. ATSDR, 1999; Mahaffey et al., 2009). The health effects of dietary Hg have been studied most extensively with respect to neurodevelopment and cardiovascular endpoints (Grandjean et al., 1999; Guallar et al., 2002; Hallgren et al., 2001; Mozaffarian et al., 2011; Myers et al., 2009; Oken et al., 2008). The epidemiologic evidence is mixed in these cases, in part because of differences in relative Hg and omega-3 fatty acids (FAs) in the available dietary fish. "
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