Mitigation Strategies for Cadmium and Arsenic in Rice

Abstract

Rice (Oryza sativa L.) is a major dietary source of not only cadmium (Cd) but also inorganic arsenic (iAs) in populations that consume rice as a staple food. When rice is cultivated under aerobic conditions, Cd in the paddy soil is solubilized and more likely to accumulate in the grain. Under flooded conditions iAs is more likely to accumulate in the grain. The application of intermittent irrigation consisting of 3 days of flooding and several days of drainage, during the heading stage of rice growth, was effective for simultaneously decreasing the accumulation of Cd and iAs in grain without negative effects on yield and quality. An alternative and promising strategy is a combination of water management and soil amendment to reduce the absorption of Cd and iAs. Growing a low-Cd-accumulating cultivar under aerobic conditions is the most practical way to simultaneously reduce the Cd and iAs contents in rice. Bacteria associated with the rice rhizosphere are involved in the formation of dimethylarsinic acid (DMA) in rice.