Wastewater analysis of psychoactive drugs: Non-enantioselective vs enantioselective methods for estimation of consumption.

The consumption of licit and illicit psychoactive drugs (PAD) is ubiquitous in all communities and a serious public health problem. Measuring drug consumption is difficult but essential for health-care professionals, risk assessment and policymakers. Different sources of information have been used for a comprehensive analysis of drug consumption. Among them, Wastewater based epidemiology (WBE) emerged as an essential and complementary methodology for estimating licit and illicit drugs consumption. This methodology can be used for quantification of unchanged drugs or their human-specific metabolites in wastewater for estimation of consumption or screening of new PAD. Although some limitations are still being pointed out (e.g., estimation of the population size, use of suitable biomarkers or pharmacokinetics studies), the non-invasive and potential for monitoring real-time data on geographical and temporal trends in drug use have been showing its capacity as a routine and complementary tool. Chromatographic methods, both non-enantioselective and enantioselective are the analytical tools used for quantification of PAD in wastewaters and further estimation of consumption. Therefore, this manuscript aims to summarize and critically discuss the works used for wastewater analysis of PAD based on WBE using non-enantioselective and enantioselective methods for estimation of consumption. Non-enantioselective methods are among the most reported including for chiral PAD. Nevertheless, a trend has been seen towards the development of enantioselective methods as most PAD are chiral and determination of the enantiomeric fraction can provide additional information (e.g., distinction between consumption or direct disposal, or manufacture processes) and fulfill some WBE gaps.