The effect of soil parameters on the bioavailability and retention of lead in rats
Malpas, Phyllis B.
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Permalink
https://hdl.handle.net/2142/22469
Description
Title
The effect of soil parameters on the bioavailability and retention of lead in rats
Author(s)
Malpas, Phyllis B.
Issue Date
1996
Doctoral Committee Chair(s)
Buck, William B.
Department of Study
Comparative Biosciences
Discipline
Comparative Biosciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Health Sciences, Toxicology
Agriculture, Soil Science
Environmental Sciences
Language
eng
Abstract
This study investigated the relationship between soil cation exchange capacity (CEC) and soil amendments (lime and phosphate) to the retention of lead in soil fed to rats. This study also related the amount of lead that can be extracted from in situ contaminated soils from a secondary smelter site to both soil properties and to the tissue lead concentrations in rats. In a six week feeding trial, 208 rats were divided into 26 groups and fed diets containing contaminated and uncontaminated soils (5% of diet) of three CEC levels that were amended with lime and/or phosphate or unamended. A soil-free negative control and lead acetate positive control group were included. Lead concentrations were measured in blood, liver, kidney, and femur. There were no significant amendment effects in the low lead soils, although there was a small CEC effect. The high lead soil groups showed no CEC effect; however, amendment type was significant and consistent across the tissues, with the lime and phosphate/lime groups generally being lower than the unamended and phosphate-amended groups. However, the total lead had more influence on the tissue values than the amendment effects. A third soil concentration (220-250 mg/kg) that did not fit into the low soil groups (40-50 mg/kg) showed a significant amendment effect for week 3 and 6 blood and femur.
The extraction studies used 4 extractants: HNO$\sb3$, EDTA, ammonium acetate (1N) and the Bray P-1 (PA) solution (0.03 M NH$\sb4$F in 0.025 M HCl). The results of these studies indicated that all of the extractable lead concentrations were well correlated with total lead, but the ammonium acetate and the PA extractants were able to extract a slightly greater amount of lead from the low CEC than the high CEC soil.
The conclusions were that sorption (CEC) effects were more notable at low lead concentrations, and solubility effects had more influence at high lead concentrations. However, the overriding effect on the bioavailability of lead to rats, in this study, was the total amount of lead in the soil.
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