1. Low-level Methyl-mercury Exposure from Fish Consumption and Child Neurodevelopment
- Author
-
Xu, Yingying
- Subjects
- Epidemiology, prenatal methylmercury exposure, child neurodevelopment, fish consumption, postnatal methylmercury exposure, Bayley scales, child IQ
- Abstract
There remains scientific uncertainty about the neurodevelopmental consequences of prenatal and postnatal exposure to low levels of methylmercury (MeHg). We examined the effects of low-level prenatal and postnatal mercury exposure from fish consumption on childhood neurodevelopmental outcomes in a longitudinal cohort.Neurodevelopment among 344 children at 1-8 years was assessed using the Bayley Scales of Infant Development-II (1,2,3y), Wechsler Preschool and Primary Scales of Intelligence-III (5y), and Wechsler Intelligence Scales for Children-IV (8y). We measured whole blood total mercury in serial maternal samples during pregnancy, and in children’s samples (cord, 1,2,3,4,5,8y). We surveyed maternal and child fish consumption and estimated intake of polyunsaturated fatty acids (PUFA). Associations between prenatal and postnatal mercury exposure and neurodevelopmental outcomes were examined using regression and structural equation modeling (SEM), adjusting for potential confounders. A majority of mothers (86%) reported consuming relatively small amounts of fish during pregnancy, mostly consuming fish with low MeHg content. Child fish consumption also included small amounts with low MeHg content. The geometric mean of maternal blood mercury was 0.64 ug/L. Children’s blood samples had lower concentrations (geometric mean range: 0.18 – 0.26 ug/L). Higher prenatal mercury concentrations were associated with lower scores on the Bayley Psychomotor Development Index (PDI). For each doubling of average maternal mercury concentration during pregnancy, the PDI decreased by 1.48 points (p=0.01). In the SEM model examining the joint effects of prenatal and postnatal mercury, each doubling of the prenatal mercury concentration was associated with a 1.55 point decrease in child PDI scores (p=0.03), and each doubling of child concurrent mercury concentration was associated with a 0.83 point decrease in PDI scores (p=0.10). We did not observe a consistent association between prenatal or postnatal mercury exposure and later child cognitive outcomes at ages 5 and 8 years. In this cohort of children with low mercury exposure from fish consumption, we found minimal evidence of detrimental effects from prenatal or postnatal mercury exposure on child cognitive abilities. However, we found negative effects from both prenatal and postnatal mercury exposure on infant and toddler motor abilities assessed at ages 1, 2, and 3 years, where prenatal exposure appeared to have a higher contribution to these mild deficits.
- Published
- 2017