Termed "Wastewater-based epidemiology", this new method of research has already been used to build data on drug-taking habits in 50 cities across Europe.

The findings, presented by the EU drugs agency (EMCDDA), aim to provide a clearer picture of drug-taking habits compared to previous methods.

Drug-use is a misunderstood, complex and highly stigmatised behaviour, which is why measuring it is such a difficult experience. Wastewater analysis is developing as a scientific discipline that has the potential to provide objective and real-time data on drug-use by examining wastewater in a particular area, rather than relying on surveys - where participants may not share their experiences accurately.

This video, created by the EMCDDA, explains their process of obtaining evidence:

The SCORE group, an associate of EMCDDA, has been conducting annual wastewater usage since 2011, but this is the first year that the results have been published mere months after the study began, meaning that the method has provided timely monitoring of trends in illicit drug use at population level.

The findings offer a valuable snapshot of the drug flow through the cities involved, revealing marked regional variations in drug use patterns:

- Methamphetamine use, generally low and traditionally concentrated in the Czech Republic and Slovakia, now appears to be present also in the east of Germany and northern Europe, particularly in cities in Finland.
- Traces of cocaine in wastewater indicate that cocaine use is highest in western and southern European cities, particularly in cities in Belgium, the Netherlands, Spain and the UK. The analysis points to very low to negligible cocaine use in the majority of eastern European cities.
- For MDMA, the 2016 wastewater data confirmed the trend established in 2015. In most cities, wastewater MDMA loads were higher in 2016 than in 2011, with sharp increases seen in some cities, which may be related to the increased purity of MDMA or increased availability and use of the drug.
- The loads of amphetamine detected in wastewater varied considerably across the study locations, with the highest levels reported in cities in the north of Europe. Amphetamine was found at much lower levels in cities in the south of Europe.
- When weekly patterns of drug use were examined, cocaine and MDMA (ecstasy) levels rose sharply at weekends in most cities, while methamphetamine use appeared to be more evenly distributed throughout the week.

To see the full results, visit the ECMDDA website:

emcdda.europa.eu