Quantification of health risks and spatial distribution of heavy metals in groundwater of Lower Himalayas, India

In this systematic research work, fifty-four groundwater samples of Solan and Shimla districts of Himachal Pradesh, India, have been analysed for heavy metals like As, Cd, Cr, Co, Cu, Ni and Pb using atomic absorption spectrophotometer as well as physico-chemical parameters like pH, redox potential, electrical conductivity and total dissolved salts (TDS). Most of the water samples were found to be alkaline. Based on their TDS values, 53 groundwater samples were considered 'fresh' and 'desirable for drinking'. The investigated groundwater samples were found to be heavily contaminated with As, Co, Cr, Ni and Pb, as their average values of 84.3, 106.7, 101.4, 84.1 and 131.9 ppb, respectively, far exceeded the guideline values recommended by World Health Organization and United States Environment Protection Agency. Doses due to ingestion via drinking water pathway and dermal absorption were computed for two different age groups of child and adult. The non-carcinogenic risk expressed in terms of target hazard quotient was found to be greater than unity for As, Co, Cr and Pb. The average carcinogenic risk of As and Cr calculated as 1.56 × 10–3 and 2.38 × 10–2, respectively, crossed the acceptable range of 10–6–10–4. It may thus be concluded that the residents of the study region have high probability of developing adverse health effects from heavy metal exposure.