Background: Inconsistent results continue to be reported from studies linking low-level prenatal lead exposure and child development. Because of limited earlier epidemiological studies with birth cohort follow up design, it still remains inconclusive that either the associations of cord blood level of toxic, and essential elements, and postnatal raising environment on neurodevelopment of children remains constant throughout childhood or change over time. Aims: This study aims to investigate the influence of in utero toxic [lead (Pb) and arsenic (As)] and essential elements [zinc (Zn)] levels on neurodevelopment of 36 months children in Chitwan valley, Nepal taking the postnatal environment into account. Study Designs and Subjects: In this birth cohort study, participants (N=100 mother-infants' pairs) were recruited in Chitwan district, Nepal. We measured Pb, As and Zn concentrations in cord blood. Postnatal raising environment (i.e., Home score or home environment hereafter) was evaluated using Home Observation for Measurement of Environment (HOME) scale. Neurodevelopment of children at 36 months of age (n=70) were assessed using Bayley Scale of Infant Development, Second Edition (BSID II). Multivariate regression was performed (n=70) to see the association of in utero toxic and essential elements level and home environment with neurodevelopment score adjusted for covariates. Results: Cord blood levels of Pb, As and Zn were not associated with any BSID II cluster scores of 36 months children. The children with relatively superior HOME score and concurrent nutritional status (weight at 36 months) showed better cognitive development (i.e., MDI scores) and motor functions than their counterparts, respectively. Conclusion: In this general population in Nepal, prenatal Pb, As and Zn levels are not important determinants of the neurodevelopment of 36-month-old children while a consistent beneficial effect of a stimulating home environment on neurodevelopmental indicators is continued.
Parajuli, R. P., Umezaki, M., Fujiwara, T., & Watanabe, C. (2015). Association of cord blood levels of lead, arsenic, and zinc and home environment with children neurodevelopment at 36 months living in Chitwan Valley, Nepal. PLoS ONE, 10(3). https://doi.org/10.1371/journal.pone.0120992