Dietary arsenic consumption and urine arsenic in an endemic population: response to improvement of drinking water quality in a 2-year consecutive study

We assessed the association between arsenic intake through water and diet, and arsenic levels in first morning-void urine under variable conditions of water contamination. This was done in a 2-year consecutive study in an endemic population. Exposure of arsenic through water and diet was assessed for participants using arsenic-contaminated water (≥50 μg L⁻¹) in a first year (group I) and for participants using water lower in arsenic (<50 μg L⁻¹) in the next year (group II). Participants with and without arsenical skin lesions were considered in the statistical analysis. Median dose of arsenic intake through drinking water in groups I and II males was 7.44 and 0.85 μg kg body wt.⁻¹day⁻¹(p <0.0001). In females, it was 5.3 and 0.63 μg kg body wt.⁻¹day⁻¹(p <0.0001) for groups I and II, respectively. Arsenic dose through diet was 3.3 and 2.6 μg kg body wt.⁻¹day⁻¹(p = 0.088) in males and 2.6 and 1.9 μg kg body wt.⁻¹day⁻¹(p = 0.0081) in females. Median arsenic levels in urine of groups I and II males were 124 and 61 μg L⁻¹(p = 0.052) and in females 130 and 52 μg L⁻¹(p = 0.0001), respectively. When arsenic levels in the water were reduced to below 50 μg L⁻¹(Indian permissible limit), total arsenic intake and arsenic intake through the water significantly decreased, but arsenic uptake through the diet was found to be not significantly affected. Moreover, it was found that drinking water mainly contributed to variations in urine arsenic concentrations. However, differences between male and female participants also indicate that not only arsenic uptake, but also many physiological factors affect arsenic behavior in the body and its excretion. As total median arsenic exposure still often exceeded 3.0 μg kg body wt.⁻¹day⁻¹(the permissible lower limit established by the Joint Expert Committee on Food Additives) after installation of the drinking water filters, it can be concluded that supplying the filtered water only may not be sufficient to minimize arsenic availability for an already endemic population.