Assessment and Control of Metals Exposures in the Residential Environment During the Early Stages of Life

Abstract

WS4-04 Abstract: Metals such as lead, arsenic, and cadmium are common contaminants at many hazardous waste sites and may pose a particular risk to young children due to differences in behavior and their increased susceptibility for neurodevelopmental impairment. Few studies have collected systematic data on concurrent exposure to multiple metals during the early stages of life or accounted for potential interactions. We conducted a longitudinal, multimedia exposure assessment study at the Tar Creek Superfund Site, a mining-related hazardous waster site contaminated by metals in mining tailings and populated by many residents of Native American descent. The objective was to evaluate the relationship between exposures to metals in the residential environment and biomarkers of absorbed metals dose at various stages of development to characterize pathways and sources of exposure. The residential environments of 50 children under 1 year of age were inspected and sampled twice at 6-month intervals. Thirty-six percent of homes lived within the Superfund site boundaries and 14% lived in 2 high-risk towns. From each home, we collected samples of respirable, airborne particles (PM2.5), house dust, drinking water, yard soil, and food to be analyzed for lead, zinc, arsenic, iron, cadmium, copper, and manganese. Metal concentrations in ambient air were assessed at 3 fixed sites and a cascade impactor was used to separate <37 μm fraction into smaller-sized particles. Although ambient air concentrations for PM10 and PM2.5 were less than the EPA standards, metals concentrations in smaller (0.1–1.0 μm) particles were approximately 3 times higher than average (<37 μm) -sized particles. In addition to the thousands of tons of mine tailings piles scattered throughout the area, the “chat,” or the smaller particles of mine tailings, has been used as gravel base for roads, parking lots, and concrete slabs in new home construction. Based on the results of an interview, 20% of residents responded that chat had been used in the foundations of their homes, 26% reported knowing of chat used in neighborhood roads, and over 40% said that chat was used in their home's driveway. This information will be used to design, implement, and evaluate a culturally based risk assessment and nutritional, behavioral, and environmental intervention strategy to reduce children's potential in-home exposures. Results from this research can be used to better understand multimedia exposure pathways and to develop practical approaches for studying complex metals mixtures in the residential environment.