Arsenic (As) is a carcinogen and the intake of inorganic As in rice is a significant risk factor for cancer in populations for whom rice is a staple foodstuff. In some cases, human As intake from the consumption of rice exceeds that from drinking water. For inorganic As, a PTWI of 15 μg/ kg body weight has been established by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). The Ministry of Agriculture, Forestry, and Fisheries of Japan analyzed the As contents of staple crops in Japan and found that As concentrations in brown rice ranged from 0.04 to 0,33 mg/ kg, with an average value of 0,16 mg/kg (n = 199). Rice is therefore a major source of dietary intake of inorganic As in the Japanese population. Contamination by As occurs to a greater extent in paddy rice than in other upland crops because anaerobic conditions in paddy soil lead to As mobilization and thus enhanced bioavailability to rice.
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