Soil Arsenic Availability and Transfer to Food Crops in Sahibganj, India with Reference to Human Health Risk

Irrigation of crops by arsenic contaminated groundwater leads to buildup of arsenic in soil and transfer to humans via bioaccumulation in crops. However, many factors, like available concentration of arsenic in soil, accumulation in edible portion of the crops and intake rate determine the final risk. The present study has attempted to characterize all these related factors. Groundwater arsenic content varied between 23 ± 5.33 to 176 ± 49 μg L −1 . Total arsenic in agricultural soil ranged from 3.92 to 7.05 mg kg −1 dry weight. Sequential extraction of soil revealed the major fraction in majority of the samples to be residual, with available fraction varying within 0.06 to 1.58 mg kg −1 , exhibiting positive correlation between total and available arsenic content in soil. Positive correlation was observed between As-Fe (R 2 = 0.55) and As-clay content (R 2 = 0.42). Accumulation in 25 plant species ranged from 0.07 to 0.58 mg kg −1 dry weight. The Bioconcentration Factor was highest in pigeon pea and significantly high in paddy. Analysis of the different parts of the plant indicated higher accumulation in potato tuber and radish, in which the below ground parts are edible. Apart from this, in the above ground edible parts, accumulation was high in wheat, maize, spinach, coriander, brinjal and cucumber. Further, the Health Risk Index, calculated on the basis of daily intake, indicated maximum risk with consumption of food according to the following order: wheat (2.18), paddy (1.13), potato (0.47), pumpkin (0.39) and spinach (0.24). Observations thus suggest high risk of food items which are generally consumed daily.