Developing Methylmercury-Targeted Strategies to Safeguard Rice Consumers

Abstract

Mitigating mercury (Hg) risk in the rice-paddy system is crucial for safeguarding food safety and human health, as rice is a main source of human exposure to neurotoxic methylmercury (MeHg). Current mitigation strategies predominantly focus on reducing the availability of inorganic Hg (IHg) for Hg methylation, achieved primarily through Hg emission control and in situ Hg immobilization. While these IHg-targeted approaches have effectively reduced MeHg bioaccumulation and subsequent human exposure, their efficacy is largely undermined by Hg transformations and fluctuating environmental conditions due to the complex and protracted pathway linking IHg from environmental sources to MeHg at the point of human exposure. In light of recent advancements in MeHg-related transformations, we emphasize the development of MeHg-targeted strategies to improve the overall efficiency of Hg risk management in rice-paddy systems. MeHg-targeted strategies include microbial regulation to diminish net MeHg production, facilitating MeHg demethylation in soils, and promoting the in vivo MeHg degradation within rice plants. Although these approaches are still in their nascent stages, they hold significant promise due to their potential high mitigation efficacy and reduced uncertainties, owing to the shorter pathway between MeHg production and human exposure. Integrating IHg- and MeHg-targeted strategies offers a comprehensive and synergistic approach, paving the way for more effective mitigation of human exposure to MeHg in rice-paddy systems.