Evaluating the protective capacity of soil heavy metals regulation limits on human health: A critical analysis concerning risk assessment - Importance of localization.

Heavy metal pollution of agricultural soil is a major global concern, prompting the establishment of maximum allowable limits (MALs) to ensure food safety and protect human health. This study collected and compared MALs for six heavy metals (As, Cd, Hg, Pb, Zn, and Cu) in agricultural soils from representative countries and organizations (EU and WHO/FAO). The research evaluated the critical health risks and efficacy of these MALs under the hypothetical scenario of metals concentrations reaching the maximum allowable level. Safe thresholds for heavy metals were then derived based on maximum acceptable health risk levels. The comparative analysis revealed significant variations in the specific limit values and terms of MALs across countries and organizations, even for the same metal. This suggests that there is no consensus among countries and organizations regarding the level of metal-related health risks. Furthermore, the risk analysis of metal concentrations reaching the maximum level accentuated heightened risks associated with As, suggesting that the current risk of soil As exposure was underestimated, particularly for children. However, soil Cu, Cd, and Zn limits generally resulted in low health risks, implying that the current limits may overestimate their hazard. Overall, the results highlight that the current MALs for soil heavy metals may not fully safeguard human health. There is a critical need to optimize current soil MALs based on localized risks and the actual impact of these metals on human health. It is suggested to appropriately lower the limits of metals (such as As) whose impact on health risks is underestimated, and cautiously increase the limits of metals (such as Cu, Cd, and Zn) that currently pose minor health risks. This approach aims to reduce both over and insufficient protection problems of soil heavy metal MALs, emphasizing the importance of considering the locality in setting these limits.

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.