Consumption of fish, fish products, and marine mammals is currently considered as the main pathway of human exposure to methylmercury (MeHg), posing a worldwide human health threat. However, recent studies have elucidated that rice consumption can be the main pathway of MeHg exposure to humans in Hg mining areas in Southwestern China.  The mechanism of MeHg accumulation in rice is a research hotspot in scientific community.

Prof. FENG Xinbin and his coworkers from Institute of Geochemistry, Chinese Academy of Sciences (IGCAS), have successfully demonstrated that, 1) the seed of rice has the highest ability to accumulate MeHg compared to other tissue; 2) the newly deposited Hg is more readily transformed to MeHg and accumulated in rice plants than Hg forms with an extended residence time in soil; 3) soil is the potential source of MeHg in the tissues of rice plants; 4) MeHg in soil is first absorbed by roots and then translocated to the above-ground parts (leaf and stalk).  During the full rice growing season only a very small amount of MeHg was retained in the root section.  In the premature plant, the majority of MeHg is located in the leaf and stalk; however, most of this MeHg is transferred to seed during the ripening period.

Those results titled “Distribution Patterns of Inorganic Mercury and Methylmercury in Tissues of Rice (Oryza sativa L.) Plants and Possible Bioaccumulation Pathways” and “The Process of Methylmercury Accumulation in Rice (Oryza sativa L.)” have been published in Journal of Agriculture and Food Chemistry (2010, 58, 4951-4958. DOI: 10.1021/jf904557x) and Environmental Science & Technology(Publication Date: March 2, 2011. DOI: 10.1021/es103384v), respectively.  The research was financed by the Chinese Academy of Sciences through a knowledge innovation project (KZCX2-YW-135) and the National Natural Science Foundation of China (20828008, 41073098, and 41073062).

 (Provided by FENG Xinbin)