Total and inorganic arsenic concentrations in rice sold in Spain, effect of cooking, and risk assessments

Rice can contain a relatively high amount of arsenic (As). We evaluated total and inorganic As concentrations in 39 samples of different types of rice sold in Spain. The analyses were performed in raw rice and in rice cooked by boiling to dryness in water spiked with As(V) (0.1-1 mu g mL(-1)). In raw rice, inorganic As represented 27-93% of total As: total As = 0.188 +/- 0.078 mu g g(-1) dry weight (dw); inorganic As = 0.114 +/- 0.046 mu g g(-1) dw. After cooking, the rice retained between 45% and 107% of the As(V) added to the cooking water, and the inorganic As concentrations ranged between 0.428 mu g g(-1) dw (0.1 mu g mL(-1) in the cooking water) and 3.89 mu g g(-1) dw (1.0 mu g mL(-1) in the cooking water). For raw rice, the inorganic As intake of the Spanish population (16 g raw rice/day) remains below the tolerable daily intake (TDI) proposed by the WHO (2.1 mu g inorganic As/day/kg body weight). In rice cooked with water contaminated with As(V), this cereal intake is sufficient to attain the TDI. The results reveal the need to consider the determination of inorganic As and the influence of cooking when evaluating the risks associated with the consumption of rice.