249-13 Distribution, Sources, and Risk Assessment of Pharmaceutically Active Compounds in Surface Waters Across Urban and Rural Catchments of South Indian Rivers

Session: Emerging Contaminants: Geochemical Insights and Impacts on Human and Environmental Health

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Pharmaceutically active compounds (PhAC) are emerging pollutants in surface water ecosystems, posing significant threats to aquatic life and contributing to the growing issue of antimicrobial resistance. This study investigates the occurrence and risk assesment of 24 PhACs from 10 various pharmaceutical classes in the surface waters of South India, with a focus on contrasting urban rivers—such as the Adyar and Cooum in Chennai—with suburban/rural rivers including the Tamirabharani and Kaveri. Surface water samples were collected in two monitoring campaigns conducted during and after one year of COVID-19 pandemic and extracted by solid-phase extraction followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) Analysis. Caffeine and carbamazepine were ubiquitously detected across Chennai’s urban rivers and canals, highlighting continuous inputs from untreated domestic wastewater. Analgesics, particularly paracetamol, showed the highest concentrations among PhACs across most sites, likely driven by its widespread over the counter (OTC) availability and high consumption. Urban rivers exhibited significantly elevated concentrations of multiple PhAC classes—including antibiotics, Angiotensin receptor blockers (ARBs) and antimicrobial agents—compared to their suburban counterparts, reflecting the influence of high population density, inadequate sewage treatment, open discharge and intensified pharmaceutical use in city environments. Site wise multivariate Principal Component Analysis (PCA) identified three major contamination sources: untreated household sewage, urban solid waste runoff, and discharge of effluents from hospitals, pharmaceutical manufacturing and storing companies. Several PhACs that were undetected or low concentrations in the first sampling during the Covid-19 pandemic were found in significantly higher levels during the second, post-pandemic sampling phase, suggesting a strong influence of anthropogenic activity and mobility on pharmaceutical loading in urban waters. Risk for antimicrobial resistance (AMR) development model presented notable risks for antibiotics such as ciprofloxacin, sulfamethoxazole, and erythromycin, particularly in densely populated urban stretches. Eco-toxicological risk assessment revealed relatively low risk to aquatic organisms overall, but still localized hotspots in the Buckingham Canal showed compound-specific threats for fish and daphnids. The PhAC levels from urban rivers were comparable to other rapidly urbanizing regions in Asia and Africa, while the absence or low levels of certain drugs common in developed countries (Ibuprofen, Sotalol and citalopram) underscore regional differences in drug usage and healthcare access.This study emphasizes the need for continuous monitoring and wastewater management strategies to mitigate the spread of pharmaceutical pollution.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11352

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