RESIDENTIAL EXPOSURES TO METALS IN HOMES NEAR THE TAR CREEK SUPERFUND SITE

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 neuro-developmental impairment. However, few studies have collected systematic data on concurrent exposure to multiple metals during the early stages of life or accounted for potential interactions. As part of the Center for Children's Environmental Health and Disease Prevention Research at the Harvard School of Public Health, we are conducting a longitudinal, multi-media exposure assessment study at the Tar Creek Superfund Site, a mining-related Superfund site contaminated by metal-enriched mining waste. Our objective is to evaluate the relationship between environmental exposures to metals and biomarkers of absorbed metals dose (as measured in blood and hair) in young children living proximate to the site. The residential environments of 50 children under 1 year of age ultimately will be sampled twice at 6 months intervals. From each home, we will collect samples of respirable, airborne particles (PM_2.5), house dust, drinking water, yard soil, and food. Samples will be analyzed for: lead, zinc, arsenic, iron, cadmium, copper, and manganese.

From July 2005-December 2005, exposure media in 35 residential homes with children under 9 months of age in Ottawa County, OK were sampled. House dust samples were collected with a portable vacuum cleaner, sieved to <125μm size fraction, and analyzed using XRF. Metal concentrations in dust varied considerably across all homes sampled (Range(ppm)): Pb (10-530), Zn (190-4600), As (9-65), Mn (50-470), Cu (12-1200), and Fe (940- 22000). Zinc dust concentrations were significantly higher (p<0.05) in homes located closest to the mining waste piles (1700 ± 1300 ppm vs. 880 ± 500 ppm). Lead dust concentrations were highly correlated with zinc concentrations (spearman correlation coefficient rS=0.82, p<0.0001) and also showed modest correlations with dust concentrations of As (rS=0.54, p<0.001), Cu (rS=0.56, p<0.001), and Fe (rS=0.67, p<0.0001) suggesting that these metals originated from common sources. Additional data from other environmental media as well relationships between various media will be evaluated as part of this ongoing study.