A prospective health risks analysis of regulatory limits for heavy metals in rice from representative organizations and countries worldwide: Are they protective?

Heavy metals contamination in rice has been one of the most public concerns globally; thus, many countries and organizations issued the maximum acceptable limits (MALs) of their concentrations in rice to regulate food safety and health risks. However, the applicability of these MALs has rarely been thoroughly evaluated. This study collected the MALs of heavy metals for rice from representative countries and organizations around the world. We assessed the critical health risks in the case of metal concentrations that reached the MALs for the first time. Results showed great variability of rice regulation limits owing to different processing methods (paddy, polished, and brown rice) and metal types (mainly focusing on inorganic As, Cd, and Pb). Risk analysis revealed that the inorganic As limits and part of Cd limits for polished rice generated relatively high health risks, indicating that their risks may be underestimated. Monte Carlo simulation further showed that the daily intake rate of rice (IRrice) is the largest contributor to total variances for the derivation of MALs, and regulation limits decreased with the augment of IRrice. Overall, we suggest a cautious reduction in the allowable limits of certain metals (such as inorganic As and part of Cd) in rice as their health risks and toxicity may be underestimated.