Assessment of uranium with toxicological and radiological implications in potable water sources of the eastern region of Kumaun Himalaya, India

In the present investigation, a total of 62 potable water samples were analyzed to assess uranium concentrations and the associated toxicological and radiological risks from the eastern region of Kumaun Himalaya, India, using LED fluorometry technique. The Oakton Benchtop device was used to measure physicochemical parameters, including pH, temperature, total dissolved solids and electrical conductivity. Uranium concentration in water samples ranged from 0.5 ± 0.1 to 96.1 ± 0.7 µg/L, with a mean value of 23.5 ± 27.7 µg/L; with 16 % of the water samples exceeding the provisional guideline value (30 µg/L) provided by the World Health Organization. Comparative analysis reveals that hand-pumped water showed a higher average (40.3 µg/L) than tap and spring water sources. Nevertheless, all samples remain below the radiological-based limit set by the Atomic Energy Regulatory Board. Radiological risks were evaluated by calculating annual effective doses and excess cancer risk. Results indicated that estimated annual effective ingestion doses for different age groups and genders were comparatively higher in males. Further, chemical risks were quantified by estimating the lifetime average daily dose and health quotient. The average excess cancer risk was found to be 3.23 × 10-5, with lifetime average daily dose ranging from 0.003 to 2.75 µg/kg/day, averaging 0.66 µg/kg/day. The investigation found no significant chemical toxicity from uranium in water, as the computed health quotient was below 1. A strong correlation was observed between uranium and total dissolved solids, with a Pearson's r value of 0.82. Statistical model, including ANOVA, indicates that the rock/soil types of the study area contribute to the uranium distribution over the region. Further, cluster analysis was also performed on the obtained data. The findings of the present study indicated that the sedimentation zone near river confluences shows elevated uranium content, likely due to the leaching of soil/rocks from the upper Himalayan terrain.