Investigation of contamination pathway and human health risk assessment from metals in milk from the cows grazing in an industrial area: a mass balance approach

The water bodies within the industrial areas are often used for the disposal of effluents leading to heavy metal contamination in water, soil, and vegetation. However, the impact of this metal enrichment on the food web has not been much explored. The present study investigates the food chain contamination of eight metals (Al, Cd, Cr, Cu, Fe, Mn, Pb, and Zn) in the milk from the cattle grazing on a shallow lake bed within the industrial town of Ranipet, India, and associated health risk from the consumption in adults and children. The average concentrations were found to be 24.93, 7.08, 3.31, 0.18, 0.12, 0.08, 0.014, and 0.008 in mg/L for Zn, Al, Fe, Cr, Pb, Mn, Cu, and Cd, respectively. The hazard indices ranged from 0.55 to 1.85 for children; the Incremental Lifetime Cancer Risk (ILCR) values of Cd and Cr were above 10 − 4 for consumption of milk in both adults and children, which signify serious health risk. The mass balance evaluates the primary intake of all the metals, except Al, are from forage; where for Al it is from the soil. The existing milk consumption patterns projected that 531 children and 1279 adults, drinking contaminated milk are at considerable risk. The analyses of tail switch hair samples indicated the cattle are also environmentally exposed to metals indicating their subclinical effect. Hence the study alerts the elevated and often overlooked risk associated with the food chain contamination from milk in the industrial belt and recommends stringent quality control and monitoring.