Comparison of the Bioavailability of Waste Laden Soils Using ''In Vivo'' ''In Vitro'' Analytical Methodology and Bioaccessibility of Radionuclides for Refinement of Exposure/Dose Estimates

The bioavailability of soil contaminants can be measured using in vitro or in vivo techniques. Since there was no standard method for intercomparison among laboratories, we compared two techniques for bioavailability estimation: in vitro dissolution and in vivo rat feeding model for a NIST-traceable soil material. Bioaccessibility was measured using a sequential soil extraction in synthetic analogues of human saliva, gastric and intestinal fluids. Bioavailability was measured in Sprague Dawley rats by determining metal levels in the major organs and urine, feces, and blood. Bioaccessibility was found to be a good indicator of relative metal bioavailability. Results are presented from bioaccessible experiments with Cesium in contaminated DOE soils, and total alpha and beta bioaccessibility. The results indicate that the modified methodology for bioaccessibility can be used for specific radionuclide analysis