Illicit drug consumption estimated by wastewater analysis in different districts of M ilan: A case study

and Aims Wastewater analysis is a new approach developed to estimate illicit drug ( ID ) consumption in large communities, such as a city. We tested the ability of this approach to detect differences in consumption in different districts of a city. Design and Methods Consumption of cocaine, heroin, tetrahydrocannabinol ( THC ) (cannabis active principle), amphetamine, methamphetamine and ecstasy was estimated by analysis of selected drug excretion residues in composite 24 h samples of untreated urban wastewater by liquid chromatography–tandem mass spectrometry. Samples were collected from the inlet of the three main M ilan wastewater treatment plants ( WWTP ), each serving a district of the city (west, center and east). In each WWTP , samples were taken daily for seven consecutive days in N ovember 2010 and M arch 2011. Results We observed significant differences of ID consumption (expressed as mg/day/1000 inhabitants) among districts: consumption of some ID was significantly higher in the eastern district ( P  < 0.01 for THC , P  < 0.001 for cocaine and P  < 0.0001 for heroin by one‐way analysis of variance), while consumption of methamphetamine and amphetamine was higher in the central area ( P  < 0.0001). Overall, from 2010 to 2011, ID consumption decreased in all the districts, in line with a recent population survey showing decreases from 25 to 55% in the annual prevalence of ID users in I taly. Discussion and Conclusions This approach may help to detect ID consumption in different districts of a city and may be useful for planning interventions aimed at specific city areas and substances. [Castiglioni S, Borsotti A, Riva F, Zuccato E. Illicit drug consumption estimated by wastewater analysis in different districts of Milan: A case study. Drug Alcohol Rev 2016;35:128–32]