Food influence on lead relative bioavailability in contaminated soils: Mechanisms and health implications

To determine the effects of dietary constituents on soil Pb oral bioavailability, Pb relative bioavailability (RBA) in 3 soils contaminated by zinc smelting (ZS), wire-rope production (WR), and metal mining (MM) was measured under fasted and fed states with 9 foods. Under fasted state, Pb-RBA was 84.4 ± 10.3, 82.6 ± 4.70, and 32.3 ± 1.10% for ZS, WR, and MM soils; however, it decreased by 1.3-3.5 fold to 23.9-58.8, 25.6-49.9, and 14.8-24.2% under fed states with foods excluding Pb-RBA with egg in WR soil (97.3 ± 4.46%), and with cabbage and egg in MM soil (40.0 ± 8.62 and 44.4 ± 0.96%). In the presence of foods, egg and pork with significantly higher protein and fat contents leaded to the highest soil Pb-RBA (44.4-97.3%), while Pb-RBA determined with mineral-rich mouse feed was 1.6-7.9 fold lower (9.41-13.5%), suggesting high fat and protein foods tended to increase soil Pb-RBA, while high mineral diets decreased soil Pb-RBA. The increased Pb-RBA of MM soil with cabbage compared to fasted state was due to high organic content in cabbage, which could increase soil Pb solubility by inhibiting Fe and Pb co-precipitation in the intestine. For accurate assessment of health risks of contaminated soils, dietary influence on soil Pb-RBA should be considered.