Health risk assessment and source identification of groundwater arsenic contamination using agglomerative hierarchical cluster analysis in selected sites from upper Eastern parts of Punjab province, Pakistan

Abstract

Geogenic contamination of Arsenic (As) poses major health threat to people living in Indus Plain of Pakistan particularly in Punjab. In this paper, we described in detail the hydrogeochemistry of As contaminated groundwaters in selected sites from Lahore, Kasur and Okara districts and its associated potential health risks. Sampling was done in 2019 and 141 groundwater samples were collected. High variability in As concentrations was observed varying between below detection level (<0.1 µg/L) and 655 µg/L. More than 85% of these samples exceeded WHO limit of 10 µg/L while 30% exceeded national limit of 50 µg/L. The results of statistical analysis and agglomerative hierarchical cluster (HCA) analyses indicate mainly pH-dependent desorption of As from mineral oxide surfaces under alkaline conditions to be responsible for As pollution with some minor controls from NO3 − and Fe-reduction in groundwaters was also seen. Furthermore, higher potential health risks were found to be associated with elevated As levels in terms of estimated average daily dosage (EDI), hazard quotient (HQ) and carcinogenic risk assessment (CR). The average values for HQ for adults, teenagers and children were found to be 9.06, 13.6 and 13.07, respectively. Meanwhile average CR values were found to be 0.004, 0.01, 0.006 mg/Kg/day in adults, teenagers and children respectively. These results suggest an increased risk of adverse health impacts in current study sites and require effective remedial measures at urgent basis.