Illicit drug consumption estimated by wastewater analysis in different districts of Milan: A case study.

Introduction 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 Milan 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 November 2010 and March 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 Italy.
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.
(© 2014 Australasian Professional Society on Alcohol and other Drugs.)