Aligning Behavioural Ecotoxicology with Real-World Water Concentrations: Current Minimum Tested Levels for Pharmaceuticals Far Exceed Environmental Reality

Jake Mitchell Martin , Jack A. Brand, Erin S. McCallum

Behavioural ecotoxicology has emerged as a key research area, offering sensitive and ecologically meaningful endpoints for detecting contaminant effects. Much of this work has focused on pharmaceutical pollutants, now widely recognised as contaminants of emerging concern. Given the field’s rapid growth and increasing data availability, we synthesised four global databases to evaluate the environmental relevance of tested concentrations—using behavioural ecotoxicology and pharmaceuticals as a case study. We compared data from over 760 behavioural studies with more than 10 million pharmaceutical occurrence data in surface water and wastewater. On average, minimum tested concentrations were 43 times higher than median surface water levels and 10 times median concentrations in wastewater. Roughly half of all compounds were never evaluated at concentrations below the upper end of wastewater detections (95th percentile). We found weak alignment between the pharmaceuticals most frequently tested and those most commonly detected in aquatic environments. These results reveal a mismatch between experimental design and environmental exposure conditions. We recommend incorporating occurrence data into dose selection, prioritising the inclusion of at least one environmentally realistic concentration—ideally near a measure of central tendency. For pharmaceuticals, we provide a consolidated database and an automated tool to support environmentally informed study design.