Project Summary (2000-2006)

This project is examining the human bioavailability of soils contaminated with lead (Pb) and arsenic (As). Through collaboration with EPA, soils were obtained from a mining site and a smelter site, which are ideal for study. Using the technique of stable Pb isotope dilution, project investigators have developed a model for estimating soil Pb bioavailability in humans. This model examines changes in the ratio of 206Pb to 207Pb in blood, following the ingestion of trace quantities of Pb-contaminated soils. In addition, the soil-amending agents currently being tested in the field by EPA are being tested to determine if they actually reduce soil Pb bioavailability in humans. This work is important because the same pre- and post-amended soils, from a former smelter site in Joplin, Missouri, are being evaluated in swine, rat and in vitro models. Finally, researchers are exploring the possibility that the ingestion of these particular soils, some of which contain trace quantities of As, may allow estimations of the urinary excretion fraction (UEF) for soil As. Collectively, these studies are improving the precision of risk assessments at sites contaminated with Pb and As.