Study reveals high THC residue load in Slovenian wastewaters

Ljubljana – All Slovenian cities are above the European average in the use of cannabis, an international study based on waste water analysis for 2021 has shown. The highest concentration of cocaine biomarker in Slovenia was found in Koper.

The study, published on Thursday by the SCORE group in association with the European Monitoring Centre for Drugs and Drug Addiction, analysed wastewater in 75 European cities from 25 countries, including Turkey.

It looked for traces of four illicit stimulant drugs (cocaine, amphetamine, methamphetamine, MDMA/ecstasy) as well as cannabis, showing the use of most of the drugs returned to the pre-pandemic levels last year after falling the year before.

Slovenia has participated in the study for the fifth year; since 2019 six Slovenian cities or urban areas have been included; Ljubljana, Domžale-Kamnik, Maribor, Koper, Novo Mesto and Velenje.

The port city of Koper had the highest levels of biomarkers of cocaine, ahead of Ljubljana, and Maribor had the lowest. With the exception of Koper, all Slovenian cities ranked below SCORE monitoring average of population-normalised loads.

Velenje in the mid-north-east had the highest concentrations of traces of ecstasy and amphetamine in its wastewaters among the Slovenian cities included in the study.

The urban areas of Domžale and Kamnik north of Ljubljana, Maribor and Koper had amphetamine below the quantification level in all samples of wastewaters. The capital Ljubljana had the highest levels of methamphetamine and THC residues.

While all Slovenian cities were above average in terms of THC concentrations, they were deep below average in methamphetamine. The most popular drug is THC and cocaine, according to the study.

Over the past five years, amphetamine and MDMA (ecstasy) levels dropped in Ljubljana, with the exception of the high level of MDMA in 2020. The trend is similar for cocaine as methamphetamine and THC use appear to be constant.

Cocaine and THC use has been on the increase in Maribor and Domžale-Kamnik as the latter has been seeing a falling trend when it comes to amphetamine. Velenje saw an increase in cocaine levels in 2021.