13 14More and more people in Bangladesh have recently become aware of the risk of drinking 15 arsenic-contaminated groundwater, and have been trying to obtain drinking water from less 16 arsenic-contaminated sources. In this study, arsenic intakes of 18 families living in one block of a rural 17 village in an arsenic-affected district of Bangladesh were evaluated to investigate their actual arsenic 18 intake via food, including from cooking water, and to estimate the contribution of each food category 19 and of drinking water to the total arsenic intake. Water consumption rates were estimated by the 20 self-reporting method. The mean drinking water intake was estimated as about 3 L/d without gender 21 difference. Arsenic intakes from food were evaluated by the duplicate portion sampling method. The 22 duplicated foods from each family were divided into four categories (cooked rice, solid food, cereals 23 for breakfast, and liquid food), and the arsenic concentrations of each food category and of the 24 drinking water were measured. The mean arsenic intake from water and food by male subjects was 25 0.18 ± 0.13 (n = 12) and that by female subjects was 0.096 ± 0.007 mg/d (n = 6), and the range for all 26 18 respondents was 0.043-0.49 mg/d. The average contributions to the total arsenic intake were, from 27 drinking water, 13%; liquid food, 4.4%; cooked rice, 56%; solid food, 11%; and cereals, 16%. Arsenic 28 intake via drinking water was not high despite the highly contaminated groundwater in the survey area 29 because many families had changed their drinking water sources to less contaminated ones. Instead, 30 cooked rice contributed most to the daily arsenic intake. Use of contaminated water for cooking by 31 several families was suspected based on comparisons of arsenic concentrations between drinking 32 water and liquid food, and between rice before and after cooking. Detailed investigation suggested that 33 six households used contaminated water for cooking but not drinking, leading to an increase of arsenic 34 intake via arsenic-contaminated cooking water. 35 36 2

The effect of rice-cooking water to the daily arsenic intake of Bangladeshi people was investigated. At the first field survey, uncooked rice and cooked rice of 29 families were collected. Their arsenic concentrations were 0.22+/-0.11 and 0.26+/-0.15 mg/kg dry wt, respectively. In 15 families, arsenic concentration in rice increased after cooking. Good correlation (R(2)=0.89) was observed between arsenic in rice-cooking water and the difference of arsenic concentration in rice by cooking. In the second survey, we collected one-day duplicated food of 18 families. As a result, we estimated that six of 18 families likely used the arsenic contaminated water for cooking rice even they drank less arsenic-contaminated water for drinking purpose. We also conducted rice-cooking experiments in the laboratory, changing arsenic concentration in rice-cooking water. Clear linear relationships were obtained between the arsenic in rice-cooking water and the difference of arsenic concentration in rice by cooking. Factors that affect arsenic concentration in cooked rice are suggested as follows: (1) arsenic concentration in uncooked rice, (2) that in rice-cooking water, (3) difference in water content of rice before and after cooking, and (4) types of rice, especially, the difference between parboiled and non-parboiled rice.

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