Wheat is an emerging exposure route for arsenic in Bihar, India

In arsenic (As) endemic areas of south-east Asia, where a subsistence rice-based diet is 19 prevalent, As exposure from food is mainly focused on rice intake. However, consumption of 20 wheat is substantial and increasing. We present a probabilistic assessment of increased cancer 21 risk from wheat-based food intake in a study population of rural Bihar, India where As exposure 22 is endemic. Total As in wheat grains (43.64±48.19 μg/kg, n=72) collected from 77 households 23 across 19 villages was found to be lower than reported As in wheat grains from other south-24 east Asian countries but higher than a previous study from Bihar. As concentration in wheat flour was used for risk estimation, bearing in mind that it was the 26 flour obtained after indigenous household processing of the grains that was used for making 27 the home-made bread (chapati) which contributed 95% of wheat intake for the studied 28 population. Interestingly, while 78% of the surveyed participants (n=154) consumed rice every 29 day, chapati was consumed every day by 99.5% of the participants. In contrast to previous 30 studies, where As concentration in wheat grain was found to be lower than the flour due to the 31 removal of the bran on grinding, we did not find any appreciable lowering of arsenic in the 32 wheat flour (49.80±74.08 μg/kg, n=58), most likely due to external contamination during 33 processing and grinding. Estimated gender adjusted excess lifetime cancer risk of 1.23x10-4 for 34 the studied rural population of Bihar indicated risk higher than the 10-4-10-6 range, typically 35 used by the USEPA as a threshold to guide regulatory values. Hence, our findings suggest As 36 exposure from wheat-based food intake to be of concern not only in As endemic areas of rural 37 Bihar but also in non-endemic areas with similar wheat-based diet due to public distribution of 38 the wheat across India.