Evaluation of the Contribution of Lead in Soil to Lead in Dust at Superfund Sites

Abstract

The concentration of lead in indoor dust is a key parameter in the Integrated Exposure Uptake Biokinetic (IEUBK) model used by the U.S. Environmental Protection Agency (USEPA) to evaluate risks to children from lead in soil. The default assumption is that the concentration of lead in indoor dust is 70% of the concentration of lead in outdoor soil. This report reviews the basis of this assumption, and compares the assumption to data obtained at mining/smelting Superfund sites in USEPA Region 8. Data for lead concentrations measured in both indoor dust and outdoor soil at a number of different properties at nine different Superfund sites were fit to a linear model (Cdust = K0 + Ksd·Csoil). Based on ordinary linear regression, values of Ksd ranged from 0.04 to 0.34. Values of Ksd estimated using a simple method to account for measurement errors yielded values from 0.04 to 0.35. These findings indicate that the concentration of lead in dust at mining/smelting sites in Region 8 is usually not as large as the IEUBK default assumption indicates. Use of the default is likely to be protective, but will likely result in an overestimation of childhood exposure and risk from lead in soil.