Illegal Substance Analysis and Environmental Risk Assessment in Küçük Menderes River, Important Basin of the Aegean Region.

Water-based studies have come into prominence for illegal substance monitoring. There are limited studies on the detection of these substances in the surface waters as opposed to wastewater. This study aims to evaluate amphetamine, benzoylecgonine, cocaine, codeine, 3,4-methylenedioxy-N-methylamphetamine, morphine, and 11-nor-Δ9- tetrahydrocannabinol-9-carboxylic acid in the Küçük Menderes (KM) River at four different stations during three different periods and assess the environmental risks. Environmental risk assessment of psychoactive substances based on the calculation of Risk Quotients (RQ) were evaluated. RQ values for amphetamine and benzoylecgonine were < 0.01 at all sampling points during all sampling periods, indicating little risk for aquatic life. Cocaine was found as environmentally high risk (RQ > 1) based on its RQ values of 1.22 and 1.37 at KM-01 and KM-02 sampling points. This research is the first report to investigate the presence of psychoactive substances and define the environmental risks of these substances in Türkiye.