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.
ACKNOWLEDGMENTS
Data used in this report were obtained by site investigations funded by the U.S. Environmental Protection Agency Superfund Program.
DISCLAIMER: SRC, Inc. is a contractor for USEPA. The authors declare there are no specific potential competing financial interests as a consequence of employment. The opinions expressed in this report are not necessarily those of the U.S. Environmental Protection Agency.
Notes
Editor's note: Superfund sites are uncontrolled hazardous waste sites that fall under the provisions of the Comprehensive Environmental Response, Compensation, and Liability Act, as amended.
aOutliers characterized as values ±3 SD of the mean were excluded.
bSecond outlier emerged after repeating the outlier analysis excluding the first outlier.
cValues in parentheses represent the 95% confidence intervals around the mean.
aValue not reported.