Accidental ingestion of contaminated soil has been recognized as an important pathway of human exposure to lead (Pb), especially for children through hand-to-mouth activities. Intake of food following the soil ingestion may affect the bioaccessibility of Pb in the gastrointestinal tract. In this study, the effect of steamed bread and spinach on the transformation and subsequent bioaccessibility of Pb in two soils was determined by the physiologically based extraction test (PBET).

The bread increased the bioaccessibility of Pb in PbCO₃-contaminated soil in the intestinal phase, but the decreased bioaccessibility of Pb was observed in the gastric phase after the steamed bread was added. The decrease was attributed to the formation of Pb phosphate precipitates However, in the soil contaminated with free Pb²⁺ or sorbed Pb forms, the steamed bread increased the Pb bioaccessibility in both gastric and intestinal phases. This was probably due to the higher dissolved organic carbon induced transformation of Fe/Mn oxides-sorbed Pb into soluble Pb-organic complex. Addition of spinach into the two soils reduced the Pb bioaccessibility in both gastic and intestinal phases. This was probably due to the fiber-induced transformation of soluble Pb-organic complex and free Pb²⁺ into less soluble sorbed Pb.