Abstract
Extensive evidence of elevated arsenic (As) in the food-chain, mainly rice, wheat and vegetables exists. Nevertheless, the importance of exposure from food towards total As exposure and associated health risks in areas with natural occurring As in drinking water is still often neglected, and accordingly mitigations are largely focused on drinking water only. In this study, the contribution of food over drinking water to overall As exposure was estimated for As exposed populations in Bihar, India. Increased lifetime cancer risk was predicted using probabilistic methods with input parameters based on detailed dietary assessment and estimation of As in drinking water, cooked rice, wheat flour and potato collected from 91 households covering 19 villages. Median total exposure was 0.83 μg/kgBW/day (5th and 95th percentiles were 0.21 and 11.1 μg/kgBW/day) and contribution of food (median = 49%) to overall exposure was almost equal to that from drinking water (median = 51%). More importantly and contrary to previous studies, food was found to contribute more than drinking water to As exposure, even when drinking water As was above the WHO provisional guide value of 10 μg/L. Median and 95th percentile excess lifetime cancer risks from food intake were 1.89 × 10−4 and 7.32 × 10−4 respectively when drinking water As was below 10 μg/L and 4.00 × 10−4 and 1.83 × 10−3 respectively when drinking water As was above 10 μg/L. Our results emphasise the importance of food related exposure in As-endemic areas, and, perhaps surprisingly, particularly in areas with high As concentrations in drinking water – this being partly ascribed to increases in food As due to cooking in high As water. These findings are timely to stress the importance of removing As from the food chain and not just drinking water in endemic areas.
Highlights
The severity of arsenic (As) contamination in the state of Bihar, located in the eastern region of India, next to West Bengal is well acknowledged (Chakraborti et al, 2003; Chakraborti et al, 2016a; Chakraborti et al, 2016b; Chakraborti et al, 2017; Kumar et al, 2016c; Richards et al, 2020; Saha, 2009)
We focused on (a) cooked rice rather than raw rice since cooking can either increase or decrease the As concentration of rice depending on cooking method, rice variety and As concentration of cooking water (Mwale et al, 2018; Mondal and Polya (2008), Raab et al, 2009); (b) wheat flour rather than wheat grain as they were the major forms in which wheat is normally consumed in rural populations of India, in Bihar; and determined As exposure from (c) potato, the main vegetable consumed throughout the year
While a wide range of As concentration in drinking water was noted, 77% of the households had As concentration in drinking water below the WHO provisional guide value of 10 μg/L, 14% had As concentration greater than or equal to 10 μg/L but less than 50 μg/L, the Indian permissible limit in absence of an alternative source (Cgwb.gov. in., 2020) and 9% had As concentration more than or equal to 50 μg/L
Summary
The severity of arsenic (As) contamination in the state of Bihar, located in the eastern region of India, next to West Bengal is well acknowledged (Chakraborti et al, 2003; Chakraborti et al, 2016a; Chakraborti et al, 2016b; Chakraborti et al, 2017; Kumar et al, 2016c; Richards et al, 2020; Saha, 2009). Out of 38 districts (the highest administrative division in a state), 22 were reported to have As in drinking water above the WHO provisional guide value of 10 μg/L (Chakraborti et al, 2018). Systematically covering all 38 districts of Bihar, just 16% of the samples (n = 273), were found to have As above the concentration of 10 μg/L (Richards et al, 2020) These differences likely reflect differences in sampling frame, successful mitigations and public education/awareness interventions by various agencies, including the Government of Bihar, over the last decade. All these studies indicate that a majority of sampled sources might have As lower than 10 μg/L
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