Impact of prenatal exposure to mercury and selenium on neurodevelopmental delay in children in the Japan environment and Children's study using the ASQ-3 questionnaire : A prospective birth cohort

Neurodevelopmental delay is associated with neurodevelopmental disorders. Prenatal metal exposure can potentially cause neurodevelopmental delays in children. This study examines whether prenatal exposure to mercury (Hg) and selenium (Se) is associated with the risk of neurodevelopmental delays in children up to 4 years of age. Children enrolled in a prospective birth cohort of the Japan Environment and Children's Study were examined. Hg and Se levels in maternal (n(child )= 48,731) and cord (n(child )= 3,083) blood were analyzed by inductively coupled plasma-mass spectrometry. Neurodevelopmental delays were assessed in children between the ages of 0.5 to 4 years using the Ages and Stages Questionnaires, Third Edition. The association between exposure and outcomes was examined using the generalized estimation equation models. In maternal blood, compared to participants with Se levels in the first quartile (83.0 to < 156 ng/g), the odds ratio (95 % confidence intervals) for problem-solving ability in children of mothers in the third (168 to < 181 ng/g) and fourth quartiles (181 to 976 ng/g) were 1.08 (1.01 to 1.14) and 1.10 (1.04 to 1.17), respectively. Furthermore, communication, gross and fine motor skills, and problem-solving delays were also observed. However, prenatal Hg levels in maternal and cord blood and Se levels in the latter were not associated with neurodevelopmental delays in children. Thus, the findings of this study suggest an association between Se levels in maternal blood and slightly increased risks of neurodevelopmental delays in children up to the age of 4 years.