Consumption of rice contaminated with potentially toxic elements (PTEs) is a major pathway for human exposure to PTEs. This is particularly true in China's so called "Cancer Villages". In this study, sewage sludge biochar (SSBC) was applied to soil (at 5% and 10%) to suppress PTE phytoavailability and as a consequence to reduce PTE levels in rice grown in mining impacted paddy soils. Risk assessment indicated that SSBC addition (10%) markedly (P ≤ 0.05) decreased the daily intake, associated with the consumption of rice, of PTEs (As, Cd, Co, Cu,Mn, Pb and Zn by: 68, 42, 55, 29, 43, 38 and 22%, respectively). In treatments containing SSBC (10%) the health quotient (HQ) indices for PTEs (except for As, Cu and Mn) were b1, indicating that SSBC suppressed the health risk associated with PTEs in rice. The addition of SSBC (10%) markedly (P ≤ 0.01) reduced AsIII (72%),dimethylarsinic acid (DMA) (74%) and AsV (62%) concentrations in rice. Consequentially, following SSBC application (10%), the incremental lifetime cancer (ILTR) value for iAs (AsIII+AsV) associated with the consumption of ricewas significantly (P≤ 0.01) reduced by 66%. These findings suggest that SSBC could be a useful soil amendment to mitigating PTE exposure, through rice consumption, in China's “Cancer Villages”.

Biochar,Metals,Rice,Bioaccumulation,Daily intake,As speciation,Cancer risk