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EFFECT OF SOIL PB INACTIVATION TREATMENTS ON BIOAVAILABILITY OF JOPLIN, MO, SMELTER CONTAMINATED SOIL PB TO RATS
Citation:
Ryan*, J A., S. L. Brown, R. L. Chaney, J. Hallifrish, Q. Xue, C. V. Kristine, Y. Patterson, AND A. D. Hill. EFFECT OF SOIL PB INACTIVATION TREATMENTS ON BIOAVAILABILITY OF JOPLIN, MO, SMELTER CONTAMINATED SOIL PB TO RATS. Presented at ASA-CSSA-SSS Annual meeting, Charlotte, MC, 10/22-25/2001.
Description:
The effects of treating contaminated soils with various soil amendments on the bioavailability of lead were assessed in the weanling rat model. The effect of treatment was assessed by comparing the adsorption of Pb of animals fed soil samples treated with (0.5%, 1% P and 2.5% Fe + 1% P as phosphoric acid; 1% P, 1% Fe + 1% P as TSP; and 10% compost soil to the adsorption of lead of animals fed unamended soils. lead soil concentrations varied from approximately 3000-5000 ppm. Groups of 7 rats were fed the appropriate mass of soil/sand as 5% of diet to corresponding target average doses of 25, 50 or 75 ug Pb/g diet for 30 days. The amount of Pb absorbed by each animal was evaluated by measuring the amount of lead in the blood, liver, kidney and bone. The amount of lead present in tissues of animals ingesting test soils was compared to that for animals ingesting lead acetate. While tissue incorporation of lead from acetate was in a linear pattern, increasing as intake of Pb increased, results from unamended and amended soils were not. Bone data were more consistent than for blood. Liver and kidney incorporation of Pb generally followed the patern of incorporation of Pb into bone. The combination of Fe + P reduced bone Pb 59, 29, and 47% as dietary Pb increased from 25, 50, 75 ug/g. Amendment of soil with 1% phosphoric acid reduced bone Pb 12, 26, and 52% as Pb intake increased, compared to comparable Pb levels of unamended soils. Results for 0.5% are less impressive. There was no reduction in bone Pb for rats consuming 75 ug/g Pb. Ingestion of 25 and 50 ug/g Pb amended with 0.5% phosphoric acid resulted in 20-30% reductions in bone Pb. Pb incorporation into bone was reduced 34 & 40% by ingestion of soil amended with 10% compost at 50 & 75 ug/g Pb (34 & 40%), but not at 25 ug/g Pb. preliminary blood data suggest that P as TSP is not as effective as phosphoric acid. Results from these experiments indicate that amendments can substantially reduce the bioavailability of lead from contaminated soil.