Heavy metal contamination in groundwater and associated human health risk in the industrial region of southern Sonbhadra, Uttar Pradesh, India

The present study region, known as "Energy capital of India", is dominated by several thermal power plant and coal mining activities. This study highlights to assess the pollution load of groundwater with reference to heavy metals (i.e. As, Hg, Cr, Cd, Fe, Cu, Mn, Co, Zn, Ni and Pb) and associated potential health risk by its consumption to local residents of Obra, Renukoot and Anpara industrial clusters of Southern Sonbhadra, by collecting 220 groundwater samples for post- and pre-monsoon seasons in the year 2015. Results show that few of the heavy metals in majority of the samples are exceeding the limit of WHO and BIS, which indicates that most of the water samples in all the three clusters are highly contaminated with Fe, Pb, Cd, Cr, As and Hg in both the seasons. Almost all samples in Caboi plot fall within the near-neutral-high metal field in both the seasons. Mean values of heavy metal pollution index (HPI) of the three clusters were found above the critical index in both the seasons. Target hazard quotient (THQ) values of Cr, Cd, As, Hg and Pb in majority of the samples of the three clusters in both the seasons display more than unity which indicate significant noncarcinogenic risk (NCR). Based on the hazard index (HI) value, children are more susceptible for health impairment than the adults. The carcinogenic risk (CR) for Cr, Pb and As was found very high than the prescribed (10^-4 -10^-6) tolerant safe guideline of cancer risk and shows higher risk for adult than children.