Mercury (Hg) vapor and monomethylmercury (MeHg) are separately potent neurotoxins. Dental amalgam restorations, which are composed of approximately 50% metallic Hg, are the principal source of human exposure to Hg vapor, while most exposure to MeHg comes from fish consumption. Both forms of Hg cross the placental and blood-brain barriers, exposing the developing fetus. Of significant concern, the human fetus appears especially vulnerable to MeHg. There is a paucity of data on the developmental effects of prenatal Hg vapor exposure, and no data on the combined exposure to Hg vapor and MeHg exposure, despite concerns that combined exposure may elevate risk via additive or synergistic mechanisms. The proposed study will build on the strength of the Seychelles Child Development Nutrition Study (SCDNS), a longitudinal cohort study examining the association between prenatal exposure to MeHg, nutritional status, and development. Residents of the Seychelles have free dental care using amalgams and consume large quantities of ocean fish. SCDNS children have been evaluated eight times and their nutritional and developmental status to date has been well characterized. Prenatal and postnatal exposure to MeHg to date has been determined by periodic sampling of the mother's/child's hair and maternal dental status during pregnancy was established by oral examinations following delivery. In the proposed study, we will conduct routine dental exams in children recording amalgam restorations placed/present/lost as a measure of postnatal Hg vapor exposure and hair analysis as a measure of postnatal MeHg exposure. Neurodevelopmental testing will occur at 72 and 96 months. Preliminary data from a prior Seychelles cohort suggests an adverse association when Hg vapor exposure (as measured by maternal amalgams present during gestation) is included in analyses.
The aim of the proposed project is to capitalize on the availability of the already well-characterized SCDNS cohort to quantify the level of risk for adverse neurodevelopmental outcomes attributable to prenatal and postnatal co-exposure to Hg vapor and MeHg. Three hypotheses will be tested: 1) The level of risk for adverse neurodevelopmental outcomes will be accentuated by combined exposure to Hg vapor and MeHg;2) Effects of prenatal exposure will be accentuated by postnatal exposure;and 3) Overall exposure effects will be modulated by prenatal nutritional factors.

National Institute of Health (NIH)
National Institute of Environmental Health Sciences (NIEHS)
Research Project (R01)
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Neurological, Aging and Musculoskeletal Epidemiology (NAME)
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Kirshner, Annette G
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University of Rochester
Public Health & Prev Medicine
Schools of Dentistry
United States
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Feiler, Marina Oktapodas; Patel, Deven; Li, Huiqi et al. (2018) The association between early-life relative telomere length and childhood neurodevelopment. Neurotoxicology 65:22-27
Yeates, Alison J; Thurston, Sally W; Li, Huiqi et al. (2017) PUFA Status and Methylmercury Exposure Are Not Associated with Leukocyte Telomere Length in Mothers or Their Children in the Seychelles Child Development Study. J Nutr 147:2018-2024
van Wijngaarden, Edwin; Harrington, Donald; Kobrosly, Roni et al. (2014) Prenatal exposure to methylmercury and LCPUFA in relation to birth weight. Ann Epidemiol 24:273-8
Watson, Gene E; van Wijngaarden, Edwin; Love, Tanzy M T et al. (2013) Neurodevelopmental outcomes at 5 years in children exposed prenatally to maternal dental amalgam: the Seychelles Child Development Nutrition Study. Neurotoxicol Teratol 39:57-62
van Wijngaarden, Edwin; Davidson, Philip W; Smith, Tristram H et al. (2013) Autism spectrum disorder phenotypes and prenatal exposure to methylmercury. Epidemiology 24:651-9
Strain, J J; McSorley, Emeir M; van Wijngaarden, Edwin et al. (2013) Choline status and neurodevelopmental outcomes at 5 years of age in the Seychelles Child Development Nutrition Study. Br J Nutr 110:330-6
McAfee, Alison J; Mulhern, Maria S; McSorley, Emeir M et al. (2012) Intakes and adequacy of potentially important nutrients for cognitive development among 5-year-old children in the Seychelles Child Development and Nutrition Study. Public Health Nutr 15:1670-7
Strain, J J; Davidson, Philip W; Thurston, Sally W et al. (2012) Maternal PUFA status but not prenatal methylmercury exposure is associated with children's language functions at age five years in the Seychelles. J Nutr 142:1943-9
Watson, Gene E; Evans, Katie; Thurston, Sally W et al. (2012) Prenatal exposure to dental amalgam in the Seychelles Child Development Nutrition Study: associations with neurodevelopmental outcomes at 9 and 30 months. Neurotoxicology 33:1511-7
Watson, Gene E; Lynch, Miranda; Myers, Gary J et al. (2011) Prenatal exposure to dental amalgam: evidence from the Seychelles Child Development Study main cohort. J Am Dent Assoc 142:1283-94

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