Rice methylmercury exposure and mitigation: a comprehensive review

Area of Science:

• Environmental Science
• Agricultural Science
• Toxicology

Background:

• Rice paddies are microbial hotspots for mercury methylation.
• Inorganic mercury is converted to toxic methylmercury, which can translocate to rice grain.

Purpose of the Study:

• To review studies on mercury and methylmercury in rice.
• To assess the impact of rice cultivation practices on mercury levels.
• To explore mitigation strategies for methylmercury in rice.

Main Methods:

• Reviewed 51 studies on rice (Oryza sativa) total mercury and methylmercury concentrations.
• Analyzed data from rice cultivated or purchased in 15 countries.
• Examined studies on aerobic rice cultivation and water management practices.

Main Results:

• Rice total mercury and methylmercury were higher in polluted sites.
• Percent methylmercury did not differ between polluted and non-polluted sites.
• Alternating wetting and drying caused soil methylmercury spikes, but grain translocation is uncertain.

Conclusions:

• Rice cultivation practices influence mercury methylation and accumulation.
• Further investigation is needed on methylmercury translocation under different water management.
• Tailored water management strategies are advisable for mercury-polluted and non-polluted sites to minimize exposure.