LUCKNOW, March 9 -- A year-long scientific assessment at the Betwa-Yamuna confluence in Hamirpur district has found arsenic and other heavy metals at levels that may pose health risks, particularly to children, prompting calls for urgent source control and seasonal monitoring. The findings come from researchers at the Birbal Sahni Institute of Palaeosciences, Lucknow. The study examined the confluence of the Betwa, a tributary river, and the Yamuna, one of the major rivers of north India and a key tributary of the Ganga. The two rivers meet in Hamirpur district, forming an important hydrological and ecological zone where water from separate catchments mixes and flows downstream. Scientists analysed monthly samples collected between June 2023 and May 2024, studying pH, Total Dissolved Solids (TDS) and temperature, along with trace metals such as arsenic, lead and cadmium. K Prasanna, a scientist involved in the research, said arsenic exceeded World Health Organisation (WHO) limits in several samples, while lead occasionally crossed guideline values. Total Dissolved Solids surpassed the prescribed 500 mg/L during pre-monsoon months, indicating solute enrichment under low-flow conditions. "The median Hazard Quotient values indicate non-carcinogenic health risks including neurological, reproductive and developmental effects linked to arsenic exposure for both adults and children, with children at higher risk. Cancer risk related to arsenic exceeded the United States Environmental Protection Agency threshold in 38% of adults and 9% of children as per the study," Prasanna said. Researchers said contaminant levels were higher at the confluence due to cumulative upstream loading and hydraulic mixing of two chemically different river systems. According to the team, sources include natural mobilisation from sediments as well as human-related inputs such as agricultural runoff, untreated effluents, industrial discharge, thermal power generation and urban sewage. "The amplified contaminant levels and associated health risks underline the need for arsenic and lead source control, seasonally resolved monitoring and community-level drinking water treatment," Prasanna said. The study recommended priority control of heavy metals at the confluence, institutionalised seasonal monitoring to capture low-flow risk and installation of community-scale treatment systems such as adsorption-based filtration, coagulation-flocculation, membrane processes and decentralised units in cities dependent on untreated river water....