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Relationship Between Total and Bioaccessible Lead on Children’s Blood Lead Levels in Urban Residential Philadelphia Soils
Bradham, K., C. Nelson, J. Kelly, A. Pomales, K. Scruto, T. Dignam, J. Misenheimer, K. Li, D. Obenour, AND D. Thomas. Relationship Between Total and Bioaccessible Lead on Children’s Blood Lead Levels in Urban Residential Philadelphia Soils. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 51(17):10005-10011, (2017).
Lead (Pb) is a potent developmental neurotoxin; even low levels of exposure in early life have the potential for profound and long-lasting health effects (Surkan et al., 2007; Bellinger, 2008). Lead occurs naturally in soils typically at concentrations that range from 10 to 50 mg/kg. Human activity has dispersed Pb in the environment, resulting in exten1970s and leaded gasoline until the mid-1980s, and contamination from various industrial sources, resulted in extensive contamination of urban soils with Pb. Urban soils often have Pb concentrations much greater than normal background levels. These concentrations frequently range from 150 mg/kg to as high as 10,000 mg/kg at the base of a home painted with lead-based paint (U.S. EPA, 1986). Because Pb does not biodegrade or dissipate over time, soil Pb levels remain elevated for many years. Elevated Pb levels in soil and dust represent significant sources of exposure for children (Laidlaw et al., 2014, von Lindern et al., 2016).sive and persistent contamination of soil and dust (Datko-Williams et al., 2014). Widespread use of leaded paint until the mid-
Relationships between total soil or bioaccessible lead (Pb), measured using an in vitro bioaccessibility assay, and children’s blood lead levels (BLL) were investigated in an urban neighborhood in Philadelphia, Pennsylvania, USA, with a history of soil Pb contamination. Soil samples from 38 homes were analyzed to determine whether accounting for the bioaccessible Pb fraction improves statistical relationships with children’s BLLs. Total soil Pb ranged from 58 to 2,821 mg/kg; the bioaccessible Pb fraction ranged from 47 to 2,567 mg/kg. Children’s BLLs ranged from 0.3 to 9.8 μg/dL. Hierarchical models were used to compare relationships between total or bioaccessible Pb in soil and children’s BLLs. Total soil Pb as the predictor accounted for 25% of the variability in child BLL; bioaccessible soil Pb as the predictor accounted for 28% of BLL variability. A bootstrapping analysis confirmed a significant increase in R2 for the model using bioaccessible soil Pb as the predictor with 99.3% of bootstraps showing a positive increase. Estimated increases of 1.4 μg/dL and 1.6 μg/dL in BLL per 1,000 mg/kg Pb in soil were observed for this study area using total and bioaccessible Pb, respectively. Children’s age did not contribute significantly to the prediction of BLLs.