Our Research Quantifying mercury contamination of rice and its impact on food security in China

Ensuring food security into the future, especially in industrializing regions, will involve not just ensuring sufficient supply and distribution, but also ensuring that food remains safe for human consumption. A key pollutant that can cause health impacts in humans is mercury, which is released into the atmosphere via coal-fired electricity generation and other industrial activities. As monomethylmercury (MMHG), it is toxic and bioaccumulative, and can cause neurotoxic impacts. Recently, rice – a staple food for over half the global population -- was identified as a potential MMHg exposure pathway to humans. In China in particular, MMHg exposure via rice ingestion is becoming an emerging food security issue. China is the world’s largest producer and consumer of rice as well as the largest source of mercury pollution in the world. Despite this, there has been little attention to exploring this problem to better understand where and when this contamination can affect food security. In particular, this is because mercury sources, deposition and biogeochemical processes governing MMHg bioaccumulation in rice are complex and vary in time and space.

The research of this project sought to better understand the issue of MMHg in rice, from the perspective of food security. There were three main objectives: 1) identify critical locations in China where the risk of MMHg is high, 2) understand the sources and processes by which MMHg contaminates rice, and 3) project future changes in MMHg levels in rice grains. To do this, the research team linked environmental modeling (including atmospheric mercury transport and rice MMHg bioaccumulation) with economic cost analysis of MMHg contamination. They used state-of-the-art tools, linking the GEOS-Chem atmospheric chemical transport model for mercury with the China-Regional Energy Model (C-REM), a global energy-economic model with provincial-level detail in China.

This project resulted in a greater understanding of present and projected future changes in MMHg levels in rice and potential impacts to food security. Results can aid in identifying policy recommendations and remediation strategies for minimizing risks and were communicated with local and national communities in China.