Children are emerging as the most vulnerable victims of toxic metal contamination in river systems, with new research flagging a far more complex and persistent threat than conventional assessments suggest.
A study by the Lucknow-based Birbal Sahni Institute of Palaeosciences, an autonomous institute under the Department of Science and Technology (DST), conducted at the Betwa–Yamuna confluence in Uttar Pradesh, has pointed to alarming exposure risks arising from contaminants such as arsenic, lead, and cadmium.
Published in Nature Scientific Reports, the study indicated that these toxic metals are not confined to the flowing water alone but are also embedded in surficial sediments, which function as hidden reservoirs of pollution. Over time, these sediments accumulate contaminants from a mix of natural processes and human activities, creating a long-term source of toxicity within river ecosystems.
What makes the situation particularly concerning is the dynamic nature of these sediments. Changes in river flow, seasonal variations, or flooding events can trigger the release of stored toxins back into the water. This process, often overlooked in routine monitoring, heightens the risk of human exposure even when surface water measurements appear within permissible limits, said the study titled, “Human health implications of metal pollution in the Betwa–Yamuna river system, India: evidence from Monte Carlo risk modelling.”
The implications are especially severe for children. Due to their lower body weight and developing physiological systems, they are more susceptible to the harmful effects of prolonged exposure to contaminated water. The study underscored that such exposure, even at low levels, can translate into significant health risks over time.
Focusing on the Betwa–Yamuna confluence, surface water samples were collected every month from June 2023 to May 2024 at a depth of about 20 cm from three locations: the Betwa River, the Yamuna River, and the Yamuna River (downstream).
These sites were chosen to track seasonal changes in water quality and to understand how the waters mix before and after the confluence in the Hamirpur district of Uttar Pradesh.
The researchers found that children face disproportionately higher non-carcinogenic risks compared to adults. Using advanced modelling techniques, the study revealed that contamination in this region is not merely a localized issue but part of a broader pattern linked to cumulative upstream pollution.
Instead of relying solely on average contamination levels, the researchers employed the Monte Carlo simulation to generate 10,000 possible exposure scenarios. These simulations incorporated variations in water consumption, body weight, and seasonal changes, allowing for a more realistic estimation of risk.
The results were striking. In nearly 67% of the simulated scenarios, children exceeded safe thresholds for non-carcinogenic health risks, as indicated by the hazard index—a widely used measure of potential adverse health effects. Arsenic exposure, in particular, was found to carry a significant carcinogenic risk when variability in real-world conditions was taken into account.
The findings also reinforce earlier observations from studies across the Ganga Plain, which identified riverbed sediments as both sinks and secondary sources of contamination. The interaction between sediment chemistry and hydrological processes plays a decisive role in determining how and when these pollutants re-enter the water system.
Researchers attributed the contamination to a combination of anthropogenic pressures and natural factors.
Agricultural runoff, untreated industrial discharge, urban sewage, and emissions from thermal power plants were identified as major contributors. At confluence zones such as the Betwa–Yamuna, the mixing of chemically distinct river waters further intensifies metal mobilization, amplifying both concentration levels and exposure risks.
The study highlighted that such locations act as convergence points for pollution loads accumulated across vast upstream regions. This cumulative effect not only elevates contamination but also complicates mitigation strategies, given the multiple and often diffuse sources of pollutants, as per the study.
For communities in rural and semi-urban areas, where dependence on river water remains high for drinking, irrigation, and daily use, the risks are immediate and sustained. Chronic exposure to contaminated water, even in small quantities, can lead to long-term health complications, with children bearing a disproportionate share of the burden, as per the lead author, K. Prasanna from the BSIP.
Other researchers were M. S. Amal and Anupam Sharma from the BSIP, Kagiso S. More and Ravi Rangarajan from the University of Doha for Science and Technology, and Ashwani Kumar Tiwari of the Jawaharlal Nehru University. They stressed the need for targeted measures to control heavy metal pollution, particularly in vulnerable hotspots such as river confluences.
The researchers also advocated for more robust and continuous monitoring systems that account for sediment-water interactions, stricter enforcement of regulations governing industrial discharge, and greater public awareness regarding safe water use.
The study also underscored the need to rethink existing approaches to water safety, placing greater emphasis on hidden sources of contamination that continue to threaten public health.
