Concentrations of cadmium and arsenic species in rice from production‐scale fields in Arkansas under variable water management

Abstract Rice ( Oryza sativa L.) accumulates arsenic when grown under flooded conditions; therefore, alternative water management strategies have shown promise in decreasing grain arsenic. We analyzed polished white rice grain from 103 field‐years of production for arsenic and cadmium. Fields were classified into either conventional flood, single aeration, or multiple aeration using measured water level. Only multiple aerations significantly decreased grain total arsenic and inorganic arsenic. Soil pH and clay content were negatively correlated with grain arsenic. Water management did not affect grain cadmium, which remained well below the Food and Agriculture Organization's Codex Alimentarius limit. Overall, 30% of rice grain samples exceeded the U.S. Food and Drug Administration's limit for inorganic arsenic of 0.1 mg/kg in infant rice cereals. When multiple samples were obtained from each field, the relative standard deviation of grain total arsenic was 20%. This study provides field‐scale validation of water management across different soils as a control on grain arsenic, although multiple aerations were necessary. Core Ideas We analyzed arsenic and cadmium in 103 field‐years of rice grown under different water management conditions. Multiple mid‐season soil aeration events were needed to decrease grain total arsenic, inorganic arsenic, and organic arsenic. 30% of samples exceeded the U.S. Food and Drug Administration (US FDA) action level of 0.1 mg/kg grain inorganic arsenic. Soil pH and clay content were negatively correlated with grain arsenic. Grain cadmium remained very low even under multiple soil aeration events.