Status of heavy metals and metalloid concentrations in water resources and associated health risks in parts of Indo-Gangetic plain, India

Groundwater is a major source for the supply of water for drinking as well as supporting the industrial and irrigation demands in the urban and peri-urban regions of Shahjahanpur, Uttar Pradesh, India. However, the groundwater quality of the area is deteriorating due to rapid urbanization, industrialization and intensive agriculture. The present study investigates the heavy metal(loid)s pollution in surface and groundwater and the associated health risks to the inhabitants. The results revealed that most of the analyzed heavy metal(loid)s remained within the acceptable limits set by the Bureau of Indian Standards (BIS, 2012) except for As, Fe, Mn and Ni. The collective impact of heavy metals on water quality was assessed using heavy metal pollution index (HPI) which revealed low pollution in November 2018 and low to medium pollution in October 2021. Ficklin-Caboi plot indicates that metals fall in 'low' to 'high' classes and their mobility in 30% and 45% of groundwater samples in November 2018 and October 2021 respectively was comparatively higher in the aqueous phase due to slightly lower pH conditions. The evaluated Non-Carcinogenic Hazard Index (HI) was significantly higher than the threshold limit (>1) for children as compared to adults. Relatively higher hazard quotient of As over Fe, Mn and Ni revealed its maximum contribution to the hazard index. The total carcinogenic risk values also exceeded the prescribed acceptable limit (1 x 10(-4)) for children compared to adults. The greater vulnerability of children can be attributed to several factors such as higher water consumption per unit of body weight of children compared to adults; toxicokinetic differences, immature metabolic enzyme systems and clearance mechanisms that result in longer half-lives of contaminants. Overall, the study reveals an escalated concern regarding heavy metal(loid)s induced health risk and recommends the adoption of conventional techniques for the removal of these metals from water resources.