Recreational drug use has become more and more accepted in society. Availability and purity are rising and new psychoactive substances (NPS) are popping up.

The aim of this study was to provide objective data on illicit drug use at a Belgian festival in order to report on arising trends. This may provide additional information to help develop preventive strategies.

A cross-sectional study took place during a music festival in the summer of 2019, where 43 samples of pooled urine were collected at four different locations and at different moments of the day. Analysis was performed using gas chromatography with a flame ionization detector (GC-FID) to determine ethanol concentrations. Drugs of abuse were quantified using liquid chromatography-tandem mass spectrometry. A qualitative analysis was performed using high-resolution mass spectrometry.

Median ethanol concentration was 0.88g/L. Cocaine, 3,4-methylenedioxymethamphetamine (MDMA), amphetamines, ketamine, and cannabis were detected in almost every sample and often in high concentrations. Furthermore, two NPS were detected and a variety of over-the-counter medication and adulterants were also found.

The findings were largely in-line with trends outlined in the European Drug Report. Striking were the relatively high concentrations of MDMA and ketamine and detection of two synthetic cathinones. Two possible adulterants of cocaine were detected, namely flecainide and amlodipine.

Music festivals are considered a high-risk setting for alcohol consumption and illicit drug use. Analysis of pooled urine samples at a festival therefore provides a valuable method to evaluate trends and to screen for new substances. Wide-spread use of classical drugs and identification of two NPS were observed during a major international music festival in Belgium. Results need to be interpreted carefully, taking into account the possibilities and limitations of the used techniques and a standardized sampling is required.