Bioavailability of arsenic in rice in arsenic endemic areas of West Bengal, India

Rice is a potentially important route of human exposure to arsenic, especially with rice-based diets. The WHO standard for As in drinking water of 10 μg L-1 has been adopted by many countries. Arsenic in water is generally inorganic and can be a mixture of arsenite (As (III)) and arsenate (As V). Arsenic in rice is of special concern because of the much higher levels of As in rice grain compared to other staple cereal crops. An effort has been made, through the present study, to take an account of arsenic speciation in rice in the arsenic affected villages of Chakdaha block, Nadia district, West Bengal, India having an arsenic concentration of irrigation water drifted from the shallow tube wells 0.32 mg l-1. The present study indicated that inorganic arsenic shared maximum arsenic load in rice straw while in grains it is considerably low. As species recovered from rice straw and grain are principally As-III and As-V. Rice grain As has been found to be principally As-III while in straw As-V predominated over As-III. The maximum dietary risk of exposure to inorganic arsenic through transplanted aus paddy in the present investigation was calculated to be almost 700 % of PTWI (Provisional Tolerable Weekly Intake) for an adult of 60 kg body weight.

Author : B Sinha and K Bhattacharyya