Project 1 – Prenatal Exposures to PAHs and Metals in an Impacted Community: Assessing Neurodevelopment Impacts and Tracing Metal Sources

Project Leaders

Goals and Importance of Research

While exposure to lead among children and the entire population has decreased over the past several decades, it is still a problem worth studying, as is interactions between lead and the various other chemicals that children are exposed to before and after birth. This study will look at a cohort of pregnant women in Durham, NC, to try and understand the types of chemicals exposures that occur during pregnancy, especially co-exposures to lead, cadmium, and polycyclic aromatic hydrocarbons (PAHs). The team will also assess associations between exposures in pregnant participants and early neurodevelopmental milestones in their children. Lastly, the team will try and determine the importance of different sources of lead in the home using isotopic analyses.

Summary

Perinatal exposure to lead remains a highly relevant pediatric environmental health problem, despite tremendous awareness and remediation efforts. Even at low levels, exposure to lead adversely impacts neurodevelopment; however, children are not exposed to lead in isolation. Most children are chronically exposed to hundreds of chemicals. Recent studies have found that pregnant women and children living in some areas of Durham, NC have elevated exposures to both lead and cadmium. Preliminary data demonstrate that lead and cadmium are also elevated in surface soils in some areas of Durham, as are the levels of polycyclic aromatic hydrocarbons (PAHs). Metals and PAHs also commonly co-occur in contaminated sites (e.g., Superfund Sites and Brownfields). Therefore, people living near these sites are exposed to mixtures of metals and PAHs simultaneously. While lead is a well-studied neurotoxicant, little research has been conducted to understand co- exposure to these compounds and their potential developmental impacts.

This project addresses prenatal exposure to mixtures of PAHs and metals in a community with known co-exposure. The researchers hypothesize that prenatal exposure to metals and PAHs is associated with neurodevelopmental changes that are greater than the impacts of lead alone. They first characterize exposures in a cohort of 400 pregnant women, leveraging resources available from an ongoing longitudinal study. Metals are measured in maternal blood samples collected during prenatal care visits, while PAHs (and other organic contaminants) are measured in silicone wristbands worn for a week in each trimester of pregnancy. Cognitive and behavioral assessments are being carried out with children during the first three years of life using a novel personal monitor and standard clinical assessments. Furthermore, they use a novel geochemical isotopic tracing approach to identify the primary sources of lead in a subgroup of the cohort that has the highest levels of exposures.

Project Aims

  1. Assess prenatal exposure to Pb, Cd, and PAHs and evaluate whether exposure patterns are clustered in areas of Durham.
  2. Assess associations between prenatal exposure to Pb, Cd and PAHs and early neurodevelopment.
  3. To estimate the relative source contributions of Pb from indoor dust, outdoor contaminated soils and drinking water (Pb pipes) using isotopic tracers.