Researchers have detected elevated levels of antidepressant drugs in several North Carolina waterways, raising concerns about the growing impact of pharmaceutical pollution on aquatic ecosystems and potentially human health.
The study, published in Environmental Science & Technology, found that rivers downstream from wastewater treatment plants contained a range of antidepressants and their byproducts, with some concentrations exceeding levels known to affect the behaviour and health of aquatic species.
Antidepressants are widely prescribed to treat conditions including depression, anxiety and sleep disorders. However, scientists estimate that up to 90% of some medications can pass through the body and enter wastewater systems. Many of these compounds are difficult to remove during conventional treatment processes, allowing them to enter rivers and streams.
Researchers from the University of North Carolina at Chapel Hill analysed water samples collected in December 2024 from four rivers located near wastewater treatment plant discharge points, as well as an isolated lake. The team screened for 34 compounds across several major classes of antidepressants.
Their findings revealed 17 antidepressant drugs or metabolites in water samples taken downstream of treatment facilities. In contrast, samples collected upstream or from the isolated lake were largely free from contamination.
The researchers found that concentrations of certain compounds were high enough to surpass thresholds previously linked to behavioural abnormalities and toxic effects in aquatic organisms, including small fish and crustaceans.
Erin Baker, the study’s corresponding author, said: ‘Findings from this study, along with others, reveal that pharmaceuticals are increasingly detected in waterways across the globe, especially near wastewater treatment plant discharge sites, posing a mounting environmental concern.’
While previous studies have demonstrated the effects of short-term exposure to individual drugs, the researchers say much less is known about the long-term consequences of exposure to multiple pharmaceuticals at once.
The findings could also have wider implications, as many of the waterways studied are used for drinking water supplies, agriculture and recreational activities.
Baker added: ‘Future research should prioritise broadening sampling efforts across global waterways to fully capture the scope of the issue. In addition, studies on effective remediation strategies for these pharmaceuticals are urgently needed to eliminate them from wastewater and mitigate this escalating challenge.’
Photo: Erin Baker, Emily Vincent