Common medications are creating an unexpected pollution pathway from rivers to land through insects

A troubling new pollution cycle has emerged as everyday medications like antibiotics, antidepressants, and painkillers travel from our medicine cabinets to rivers and then back onto land through an unexpected carrier: flying insects. Scientists are growing increasingly concerned about this poorly understood contamination pathway that could be spreading pharmaceutical pollutants throughout ecosystems.

New research from the University of South Bohemia reveals that aquatic insects such as caddisflies and mayflies are absorbing these chemical contaminants from polluted waterways, then carrying them to terrestrial environments when consumed by land-based predators. The study’s most alarming finding involves sertraline, the active ingredient in the widely prescribed antidepressant Zoloft, which actually becomes more concentrated as it moves up through the insects’ life cycles—a process called bioamplification. Other concerning compounds include additional antidepressants like those found in Effexor, as well as asthma medications.

While lead researcher Marek Let notes that pharmaceutical concentrations are generally lower than pesticide contamination, he emphasizes that some medical compounds can be “incredibly toxic” to wildlife. The findings highlight a critical gap in our understanding of how human medications affect natural ecosystems, particularly as these chemicals prove capable of moving between aquatic and terrestrial environments through biological carriers.

The research underscores that simply building more wastewater treatment plants won’t solve the problem, since even treated water can contain pharmaceutical residues. Instead, experts argue for reducing the overall input of these contaminants into water systems, though specific solutions remain unclear as this emerging pollution pathway continues to be studied.