Effect of Feeding Mice Soluble Metals and Heavy Metal Contaminated Soil on Feces Metal Concentrations.

The effect of heavy metal availability and interaction in feed on feces heavy metal excretion in mice has rarely been investigated. In this work, feed containing a polluted soil (total Cd = 6.34, total Pb = 387 mg kg) amended with phosphate, bentonite and lime, or feed spiked with soluble Pb and Cd were fed to mice for 10 days. Feces were collected on Day 2 and Day 10 and analyzed for Cd, Cu, Mn, Ni, Pb and Zn concentrations. Results indicated that Day 10 samples had 10% greater heavy metal concentrations in some treatments than Day 2. For the Pb and Cd spiked treatments, significant positive correlations were found between Pb and Cd rates and feces Pb and Cd concentrations on both dates. Significantly greater feces Pb and Cd concentrations were found in Day 10 samples than in Day 2 samples. Significant correlations were also found between feed Pb and Cd spiking rates and feces Cu, Mn, Ni and Zn concentrations, indicating mouse metal absorption dynamics and metal interactions. Although the phosphate and lime amended soils had lower DTPA-Pb and Cd than the unamended soil (6.2-17.9%, p < 0.05), no significant difference was found for feces Pb and Cd concentrations between treatments. A marginally negative correlation (p = 0.073) between soil DTPA-Zn and feces Zn concentration for Day 2 samples implied the soil amendment only affected mice absorption of Zn. Overall results imply that mice feces heavy metal concentrations can be used to indicate heavy metal absorption from feed and metal interactions in mice.