Illicit Drugs Along the Ebro River Basin: Occurrence in Surface and Wastewater and Derived Consumption Estimations

Abstract

The study of illicit drugs and metabolites in the aquatic environment has a double objective: (1) to investigate the environmental concentrations of this group of emerging contaminants in order to assess their potential ecotoxicological risk and (2) to estimate drug abuse by the population at the community level. The present work reports on the occurrence of illicit drugs and metabolites in waste and surface waters collected along the Ebro River basin (NE Spain) and evaluates the contribution of discharged treated wastewaters to the presence of these compounds in river waters. Concentrations of drug residues in influent wastewaters were used to back calculate illicit drug use in the areas served by the investigated wastewater treatment facilities. Cocaine, benzoylecgonine, ephedrine, and ecstasy were identified as the most ubiquitous and abundant compounds in the area of study. Heroin, 6-acetyl morphine, lysergic compounds, and Δ9-tetrahydrocannabinol (THC) were the compounds less frequently identified in the investigated samples. Overall, removal of illicit drugs and metabolites in the investigated wastewater treatment plants was satisfactory. However, ecstasy, methamphetamine, nor-LSD, and 11-nor-9-carboxy-THC were occasionally found at higher concentrations in effluent than in influent waters. Dilution of discharged treated waters resulted in total levels of illicit drugs and metabolites in surface waters at the low ng/L range. Estimates of illicit drug use pointed out cocaine as the most consumed drug in the area of study, followed by cannabis, amphetamine, heroin, ecstasy, and methamphetamine.