Heavy Metal Pollution in River Ulhas, Maharashtra, India: Unraveling Contamination Dynamics Through Pollution Indices, Multivariate Analysis, and Health Risk Assessment

River water contamination with heavy metals (HMs), particularly induced by human activity, is a major problem, especially when utilised as drinking water supply. Inspite of many attempts and mitigating techniques, waterways get contaminated. As a result, we present a novel investigation to explore the HM content of the Ulhas River, an urban river near Mumbai in Maharashtra, India, which provides 320 million-litre water per-day for drinking. This study utilises pollution metrics, multivariate analysis, and health risk assessment to provide a comprehensive evaluation of contaminant levels. Nine HMs (Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn) were tested for 10 specimens monthly from October 2022 to September 2023 totaling 120 specimens. With the exception of Fe and Mn, all other HM fell below the permitted levels. Downstream sites were found to be more contaminated than upstream ones. Several indices, including HM pollution, HM assessment, degree of contamination, and water pollution, suggested minimum river pollution. Multivariate analysis found that metals had anthropogenic sources. Finally, health risk assessment found that the metals had no significant non-carcinogenic impacts on children and adults via ingestion and cutaneous routes; nonetheless, children and adults were exposed to carcinogenic effects, with children being more vulnerable than adults. The study's results demonstrate that, inspite of being subjected to moderate to low levels of HM pollution, the river has serious carcinogenic effects on the communities that rely on it for drinking water. Thus, long-term management plans and frequent monitoring, along with HM abatement measures, will minimise river pollution.