Toxicological risk assessment of protracted ingestion of uranium in groundwater

Groundwater samples have been collected from far-reaching locations in Solan and Shimla districts of Himachal Pradesh, India, and studied for uranium concentration using LED fluorimetry. In this region, uranium in groundwater varies from 0.12 to 19.43 μg L^-1. Radiological and chemical toxicity is accounted for different uranium isotopes. The average mortality risk for uranium isotopes ²³⁴U, ²³⁵U, and ²³⁸U are 2.6 × 10^-12, 3.5 × 10^-10, and 5.9 × 10^-8, respectively. Similarly, the mean morbidity risk for ²³⁴U, ²³⁵U and ²³⁸U are 4.1 × 10^-12, 5.6 × 10^-10 and 9.5 × 10^-8, respectively. An attempt has also been made to calculate doses for different age-groups. Highest doses, ranging from 0.30 to 48.23 µSv year^-1, are imparted to infants of 7-12 months of age which makes them the most vulnerable group of population. Using Hair Compartmental Model for uranium and mean daily uranium intake of 3.406 μg for 60-year exposure period, organ-specific doses due to uranium radioisotopes, retention in prime organs/tissues and excretion rates via urine, feces and hair pathway are estimated. In this manuscript, the transfer coefficients for kidney, liver, skeleton, GI tract, soft tissues, urinary bladder, and blood are analyzed. Hair compartment model and ICRP's biokinetic model are compared in terms of uranium load in different organs after 60 years of protracted ingestion. The study on biokinetic behavior of uranium is the first of its kind in the area which is dedicated to environmental and social cause.