Ingested Soil: Bioavailability of Sorbed Lead, Cadmium, Cesium, Iodine, and Mercury
1995
Sheppard, S. C. | Evenden, W. G. | Schwartz, W. J.
Ingestion of soil, inadvertent or otherwise, is an important route of exposure for contaminants that are not geochemically or biologically mobile. There is little known about the bioavailability of these contaminants, especially when the contaminants are sorbed onto native soil particles. We investigated this with in vitro acid-extraction and enzymolysis experiments and with in vivo single and chronic exposure studies with mice (Mus musculus). The only anion studied was ¹²⁵I, and soil in the diet had no effect on the carcass ¹²⁵I content. The bioavailability of the cations tested decreased in the order of ¹³⁴Cs > ²⁰³Hg > ¹¹⁵Cd = ²¹⁰Pb, and the effect of soil in the diet on concentrations in the carcass decreased in the same order. Soil in the diet significantly decreased the bioavallability of ¹³⁴Cs, by more than four-fold, whereas the effect on ²¹⁰Pb was only ≈1.1-fold and was not significant. The results of the in vitro digestions ordered the elements in the same way as observed in the in vivo analyses. These results indicate that for contaminants that are not very mobile and are sorbed onto native soil particles, the presence of soil in the diet does not markedly affect bioavailability in the gut.
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