Environmental fate of illicit drugs and new psychoactive substances in aquatic systems: Impact, critical insights, and future directions.

Illicit drugs and novel psychoactive substances (NPS) in aquatic environments pose growing ecological and public health concerns due to their persistence and toxicity. Released mainly via wastewater and runoff, their transport and fate are influenced by microbial degradation, hydrology, and bioaccumulation. These compounds have been detected in freshwater and marine ecosystems, causing endocrine disruption and toxicity in aquatic organisms, with potential human exposure through water and food. Advances in high-resolution mass spectrometry (HRMS) have improved their detection, while treatment technologies such as advanced oxidation, membrane filtration, and bioremediation are being developed to remove these residues. This review integrates findings from environmental chemistry, ecotoxicology, and public health to assess the sources, behavior, impacts, and mitigation of illicit drugs and NPS in aquatic systems. It highlights the complexity of these contaminants and identifies critical knowledge gaps that must be addressed to support effective monitoring, risk assessment, and regulatory strategies.