ARSENIC ACCUMULATION IN BROWN (UNPOLISHED) RICE GRAIN: A FIELD SCALE STUDY IN RURAL WEST BENGAL, INDIA

Rice (Oryza sativa) is a major dietary component to the population in rural Bengal (West Bengal, India and Bangladesh). Recently rice has been considered as an important dietary exposure route of inorganic arsenic (iAs) to the human system. The present study includes a well-structured questionnaire based survey followed by laboratory analysis to find out major varieties of rice that are mostly consumed by the population and their potentiality as a exposure route of As to the population of Debogram , West Bengal. From the present survey it has been observed that brown rice (unpolished) is often the most consumed rice variety among the population (ca. 70-80%), because of its low cost compare to polished white rice and aroma rice (Basmati). Moreover people think it takes longer time to digest and thus they feel less hungry, though amount of consumption varies with age and gender. Classification of the brown rice has also been carried out according to grain size, to demonstrate the variability and trends of the mean As concentration in different variety of brown rice. It indicates that mean As concentration increases with decreasing grain size of brown rice (mean: Short bold- 0.207; Medium slender - 0.161; Long slender - 0.154). Present study also indicates higher concentration of As (mean: 0.174mg/kg) in rice of this region compared to our earlier study in Chakdaha (mean: 0.117 mg/kg), another As hot spot area in West Bengal. The increase of As concentration is significant (~49%) in between earlier study and this study. This suggests that regionally As content in rice varies considerably. It has found that As concentration is significantly low in Indian aroma rice and can be safely recommended as a dietary food. Finally the value of Maximum Tolerable Daily Intake (MTDI) has been estimated to overview the risk from consumption of brown rice based diet.