Prenatal exposure to lead and neurodevelopment in childhood

Lead (Pb) is extremely toxic environmental chemical and higher concentration of lead increases the risk of irreversible neurological, cognitive and physical impairments.  The sources of lead exposure are primarily linked to industrial processes contaminating food and drinking water, as well as domestic sources. Both prenatal and postnatal exposure to lead can impair growth and cognitive development in children. The timing of exposure might play a major role in determining the effect on the developing brain. Due to high maternal-fetal transfer of lead across the placenta, lead exposure likely starts prenatally and exposure early in life may be related to more adverse consequences and more profound cognitive impairment and deficits. Lead exposure in late pregnancy has been associated with adverse mental development in infancy and specifically with poorer executive functioning and social emotional behaviors in children. Still, detailed information on how lead exposure during pregnancy and in infancy impacts specific cognitive functions, including executive functions during childhood is lacking, especially among vulnerable infants that have multiple risks for poor development.  Inflammation and oxidative stress due to lead exposure may be important mediating factors underlying the link between lead exposure in early life and neurodevelopment outcomes, but needs further investigation. 

The importance of investigating lead exposure and neurodevelopment outcomes in Low to middle income countries (LMIC) such as Nepal, is underscored by the high level of lead exposure from products such as paints, cosmetics, toys and even fuels in these settings. In other words, young children in Nepal are at high risk of elevated blood lead concentrations which has potentially lifelong adverse consequences for their health and neurodevelopment.

The overall aim of this PhD project is to explore the association between lead exposure during pregnancy and child neurodevelopment through early childhood. The current project will be based on longitudinal data from a community-based study following mothers from early pregnancy and their offspring until they are 60 months. The sample consist of 800 pregnant women who were residing in the Bhaktapur district, Nepal. They originally participated in a large community-based, individually randomized, double-blinded placebo-controlled trial measuring the effects of daily vitamin B12 supplementation from early pregnancy (<15 weeks of gestation) up to 6 months post-partum on child growth and neurodevelopment. (https://www.uib.no/en/cismac/117184/b12-pregnancy).