Assessment of relative bioavailability of heavy metals in soil using in vivo mouse model and its implication for risk assessment compared with bioaccessibility using in vitro assay.

There is limited study to simultaneously determine the relative bioavailability of heavy metals such as Cd, Pb, Cu, Cr(VI), and Ni in soil samples. In the present study, the bioaccessibility of heavy metals using in vitro assay was compared with the relative bioavailability of heavy metals using in vivo mouse model. The bioaccessibility of heavy metals ranged from 9.05 ± 0.97 % (Cr) to 42.8 ± 3.52 % (Cd). The uptake profile of heavy metals in soil and solution samples in mouse revealed that the uptake kinetics could be fitted to a two-compartment model. The relative bioavailability of heavy meals ranged from 34.8 ± 7.0 % (Ni) to 131 ± 20.3 % (Cu). Poor correlation between bioaccessibility and relative bioavailability of heavy metals was observed (r (2) = 0.11, p > 0.05). The relative bioavailability of heavy metals was significantly higher than the bioaccessibility of heavy metals (p < 0.05). The present study indicated that the in vitro digestion method should be carefully employed in risk assessment.