A Review on Arsenic in Rice

Arsenic(As) is now regarded as one of the most serious contaminants as a typical noxious element,especially inorganic arsenic. Indeed, arsenic has a chronic poisoning effect in human body. Recent studies have shown that rice is much more efficient in assimilating arsenic into its straw and grains than other staple cereal crops, and consumption of rice constitutes a large proportion of dietary intake of arsenic. Therefore, scientists pay a high degree of attention to arsenic in rice. In rice total As content varies from 0.005 to 0.710 mg/kg. Arsenic speciation in rice grain is dominated by inorganic As(Ⅲ+V) and dimethylarsinic(DMA). The inorganic As content in rice varies from 10% to 90% of total As. Now, studies have shown that there are two types of arsenic contained rice, one with arsenic speciation dominated by DMA, and the other by inorganic arsenic. Both of them show an increasing trend in DMA/As(Ⅲ+V) content with rising total arsenic. The flooded conditions is one of the main reasons for enhanced arsenic accumulation in rice, and growing rice aerobically can dramatically decrease the arsenic transfer from soil to rice. Differing chemical states of arsenic, the mechanism of arsenic mobility in rhizosphere and mediated by microbial activity is need to be further researched in the near future. In addition, molecular approaches and functional genomics may also help understand the mechanisms of arsenic transportation and transform in rice.