Full length articleAssessment of cadmium bioaccessibility to predict its bioavailability in contaminated soils

- Cd bioaccessibility in soils was determined using UBM, SBRC, IVG, and PBET assays.
- Cd relative bioavailability in contaminated soils was determined using a mouse model.
- A 10-d steady state dosing was used with Cd in kidneys plus liver as a biomarker.
- PBET has the potential to predict Cd bioavailability in contaminated soils.

In vitro assays have been developed to determine metal bioaccessibility in contaminated soils; however, their application to Cd is limited. To assess their suitability to determine Cd relative bioavailability (RBA), Cd-RBA in 12 contaminated soils containing 3.00-296 mg kg− 1 Cd were determined using a mouse model and compared with Cd bioaccessibility data based on four assays including the UBM, SBRC, IVG, and PBET. After being administered feed amended with soil or CdCl2 for 10-day, the Cd concentrations in the mouse liver and/or kidneys were used as biomarkers to estimate Cd-RBA. Cd-RBA was comparable at 34-90% and 40-78% based on mouse liver and kidneys with RSD of 7.10-8.99%, and 37-84% based on mouse liver plus kidneys with lower RSD of 5.8%. Cadmium bioaccessibility in soils varied with assays, with 61-99, 59-103, 54-107, and 35-97% in the gastric phase and 20-56, 38-77, 42-88, and 19-64% in the intestinal phase of the UBM, SBRC, IVG and PBET assays. Based on the combined biomarker of liver plus kidneys, better correlation was observed for PBET (r2 = 0.61-0.70) than those for IVG, UBM and SBRC assays (0.12-0.52). The monthly Cd intake in children was 0.24-23.9 μg kg− 1 using total Cd concentration in soils, which was reduced by 43% to 0.18-12.3 μg kg− 1 using bioavailable Cd. Our data suggest it is important to consider Cd-RBA to assess risk associated with contaminated soils and the PBET may have potential to predict Cd-RBA in contaminated soils.

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