High geological background concentrations of As and Cd in karstic soils may not contribute to greater risks to human health via rice consumption

High geological background concentrations of toxic metal(loid)s arsenic (As) and cadmium (Cd) from natural enrichment in soils of karst regions have attracted much attention. In this study, paired soil-rice samples were collected from karst and non-karst regions in Guangxi, China to assess the potential risks of metal(loid) transfer from soil to rice grains, and rice grains to humans. Our results indicate that the karstic soils had greater As (25.7 vs. 12.4 mg·kg