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EFFECTS OF TREATMENTS ON SOIL-LEAD BIOAVAILABILITY: IMPLICATIONS OF IN-VITRO EXTRACTION TESTING
Citation:
Ruby, M. G., S. L. Brown, K G. Scheckel*, AND D Allen*. EFFECTS OF TREATMENTS ON SOIL-LEAD BIOAVAILABILITY: IMPLICATIONS OF IN-VITRO EXTRACTION TESTING. Presented at American Society of Agronomy Annual Meeting, Charlotte, NC, 10/21-25/2001.
Description:
A field-scale study on the use of phosphate amendments to reduce lead bioavailabity from soil is being conducted at the Joplin site. One of the tools used to evaluate whether lead bioavailability is being reduced is an in vitro extraction test. The in vitro test simulates the gastric environment to establish the fraction of soil lead that wold be solubilized in the gastric environment, and therefore would be available for adsorption (i.e., the "bioaccessible" fraction). At the Joplin site, the in vitro data have been used to screen various phosphate amendments for their efficacy, and are being compared to in vivo results from rats, swine, and humans to establish whether the in vitro test produces data that are comparable to laboratory animals and humans. Data from three independent laboratories, each performing the same in vitro test method, indicate an inverse correlation between extraction test pH and lead bioaccessibility. This effect is more pronounced for phosphate-amended soils than for native soils. Comparison of the in vivo lead bioavailability results for rats, swine, and humans, to the in vitro results suggests that an extraction test pH of approximately 2.3 yields the best in vivo to in vitro correlation.