Human health risk assessment using Monte Carlo simulations for groundwater with uranium in southern India

Uranium naturally occurs in groundwater and its concentration is mostly controlled by the geology of an area. The regular human consumption of groundwater with uranium causes health effects and hence the assessment of radiological and chemical toxicity effects on humans is essential. Hence, the present study was carried out to assess the general hydrochemistry of groundwater in different geological formations of southern India and its relation to uranium as well as to estimate the health risks posed to humans due to consumption of groundwater with uranium using both deterministic and probabilistic approaches. Four river basins representing the major geological formations of southern India were chosen for this study, from where a total of 141 groundwater samples were collected in the year 2016 and analyzed for the concentration of major ions and uranium. The groundwater occurring in granites had high concentration of uranium followed by gneiss and charnockites. Radiological risks to humans were higher in granitic terrain of Bhima basin, where about 1 in 10,000 may get affected due to cancer. The chemical toxicity risks were higher for the people in granite and gneissic terrain of Bhima basin followed by the people in charnockite terrain of Vaniyar basin. The deterministic method has overestimated the actual risk in comparison to the probabilistic risk assessment. The sensitivity analysis indicates that increase of exposure frequency and ingestion rates increases the chemical risks, whereas decrease of body weight increases the chemical risk. Therefore, the probabilistic approach is much superior to deterministic method since it exhibits variability in the values. The current study highlights the risks to humans by consuming groundwater with uranium, emphasizing on the urgent need for supplying treated water to the community.