The Lisbon based European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) has published a report which reveals levels of drug consumption across Europe. Data was gathered by testing wastewater for illegal drugs in around 80 cities across 23 countries. The authors of the report say it provides a valuable snapshot of the drug flow through the cities involved, revealing marked geographical variations.

The science of wastewater analysis is in its infancy, being developed in the 1990s as a tool for monitoring the environmental impact of liquid household waste. Professionals from many different scientific fields are involved in testing and analysis, such as sewage engineering, physiology, and biochemistry. Since 2011 the EMCDDA and an organisation called Sewage analysis CORE Group-Europe (SCORE), have used wastewater analysis to estimate the consumption of illegal drugs in Europe. 

To survey the drug habits of these communities scientists took samples from sewage that was piped into wastewater treatment plants within each city tested. They tested the samples for illicit drugs by measuring the levels of metabolites excreted from urine. They test identify metabolites of cocaine, crack cocaine, cannabis, amphetamine, methamphetamine and MDMA, but not for heroin as its metabolite was found to be unstable in water.

Key findings from the 2021 study include:

• Results showed distinct geographical and temporal patterns of drug use across all of the European cities. Although levels varied between locations, all illicit drugs were shown to be in nearly all cities.
• Levels of the cocaine metabolite Benzoylecgonine (BE) were found to be highest in the western and southern European cities, especially highest in the cities in Belgium, the Netherlands and Spain. London has previously been found to have one of the highest levels of cocaine use in European cities, however, Bristol was the only British city covered in the study. Eastern European cities had low levels of cocaine use, although this has increased in recent years.
• Amphetamine levels varied widely from city to city, the highest levels were recorded in the north and east of Europe, also in Sweden, Belgium, the Netherlands and Finland. This follows a trend seen in previous years.
• Methamphetamine use which was usually low and only concentrated in Czechia and Slovakia was found this year in Belgium, the east of Germany, Spain, Turkey and northern Europe. Methamphetamine levels in other locations were very low to negligible.
• MDMA levels peaked in cities in Belgium, Germany, the Netherlands, Sweden and Norway.
• Spain, Croatia, the Netherlands and Slovenia all had the highest loads of the cannabis metabolite THC-COOH.

The study, which covers the wastewater of almost 45 million people, also found the only drug not to have an increase in use was MDMA, believed to be due to the long term closure of nightclubs during lockdowns during COVID-19. Cannabis and cocaine use was shown to have continued on an upward curve throughout the pandemic. 

Differences in the levels of drugs found, and which drugs are found in the studied cities can be explained by many factors, including; levels of prohibition and law enforcement, the ability of consumers to obtain certain drugs, levels of nightlife, student population densities and age demographics. Cocaine and MDMA levels were usually found to be higher in larger cities compared to rural areas, this was not found to be the case with cannabis and amphetamines.

“The results show both a rise and spread for most of the substances studied, reflecting a drugs problem that is both pervasive and complex,” EMCDDA director Alexis Goosdeel said.