Impact of wastewaters and hospital effluents on the occurrence of controlled substances in surface waters

We have investigated the occurrence of controlled drugs in two rivers, two wastewater treatment plants (WWTPs) and five hospital effluents in Taipei, Taiwan, and report here the concentrations of controlled drugs used as prescription medication or drugs of abuse. Of the target drugs, morphine, codeine, methamphetamines and ketamine were observed in significant quantities in hospital effluents, with maximum concentrations of 1240, 378, 260 and 206 ng L−1, respectively. The other six compounds (including metabolites) were found at trace levels or below the method detection limits. In addition, the high occurrence in river waters of methamphetamine, codeine and ketamine (maximum values 405, 57, and 341 ng L−1, respectively) indicated the significant prevalence of these controlled drugs. This study demonstrated that effluents from hospitals and clinics and treated WWTP effluents contribute to the controlled substances that eventually reach natural rivers. We hypothesize that the occurrence of controlled drugs in the environment can be attributed to two main sources: (1) substance abuse by individuals and (2) treatment with prescription medication for acute and chronic pain. The presence of these contaminants in the aquatic environment may pose significant risk to aquatic and human life. Further studies are needed for verification and may contribute to the development of sustainable strategies for environmental remediation.