Various tools are used to monitor the supply of illicit drugs: police and custom seizures, self-reported user surveys, and analysis of biological samples from users and of waste water. Results from analysis of biological samples are interesting, as they prove actual use rather than merely supply of a drug. To increase sensitivity of such tool, it is important to target a population considered as potential users of a given drug type. The aim of the present study was to assess the interest of analyzing dry toilet residue and urine from urinals, collected during an electronic music festival, to monitor use of 20 recreational drugs: amphetamine, methamphetamine, MDA, MDMA, methylone, mephedrone, 4-MEC, MDPV, ketamine, methoxetamine, N, N-dimethyltryptamine, 2C-P, 25I-NBOMe, ecgonine methylester, morphine, codeine, pholcodine, dextromethorphan, JWH-073 and UR-144.

Samples (n=11) were collected during a psychedelic trance music festival (2013): 3 pools of urine from 3 urinals and solid and liquid (leachate) waste from 4 dry toilets. Solid waste from dry toilets was analyzed before and after drying (2 days at 40°C). Samples (500±5mg for solid residues and 1mL for liquids) were analyzed on GC-MS/MS after liquid/liquid extraction. Semiquantification was performed by internal calibration using codeined3, ketamine-d4 and amphetamine-d5 as internal standards (IS).

Amphetamine, MDMA, MDA, ketamine, morphine and codeine were detected in all samples. Methamphetamine was detected in all samples except in leachate from the 4 dry toilets. None of the other 13 drugs were detected. Comparing analyte/IS ratios in the various samples, increasing concentrations were found in leachate, urine, wet solid waste and dry solid waste.

This study demonstrates the interest of analyzing dry toilet residue and urine from urinals to monitor drug used. Analysis of solid waste from dry toilets seems more effective than analysis of leachate or urine for detecting consumption of recreational drugs in samples collected during a festival. Dry solid waste proved to be the most suitable samples for analysis, due to higher concentration in compounds and, from a practical point of view, easier storage and conservation. MDMA was the drug detected in the greatest amounts; ketamine seemed more widely used than methoxetamine, despite the increasing interest declared by consumers for the latter. A striking point is the absence of detection of the new psychoactive substances include in the study. It can reflect either the limits of the assay or the consumption pattern of this festival.