Wastewater analysis of drug-taking in 50 European cities
The latest findings from the largest European project in the emerging science of wastewater analysis were released last month (13 December 2016) by the Europe-wide SCORE group, in association with the EU drugs agency (EMCDDA). The project analysed wastewater in over 50 European cities in 18 European countries in March 2016 to explore the drug-taking behaviours of their inhabitants.
From London to Nicosia and from Oslo to Lisbon, the study analysed daily wastewater samples in the catchment areas of wastewater treatment plants (WWTPs) over a one-week period. Wastewater from approximately 25 million people was analysed for traces of four illicit drugs: amphetamine, cocaine, MDMA (ecstasy) and methamphetamine.
Wastewater based epidemiology is a rapidly developing scientific discipline with the potential for monitoring near-real-time, population-level trends in illicit drug use. By sampling a known source of wastewater, such as a sewage influent to a wastewater treatment plant, scientists can now estimate the quantity of drugs used in a community by measuring the levels of illicit drugs and their metabolites excreted in urine (see the motion graphic below for a full explanation).
Near real-time results
The SCORE group has been conducting annual wastewater monitoring campaigns since 2011. This is the first time, however, that data are published within only a few months of the campaign, underlining the potential of this method for the timely monitoring of trends in illicit drug use at population level.
The results were released through an innovative interactive map and chart-based tool allowing the user to look at geographical and temporal patterns and zoom in on results per city.
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.
The wastewater analysis in London was only undertaken for cocaine. The methodology allows consumption to be compared between cities with the unit of measurement being the milligrams of cocaine used for every thousand people per day.
As you can see, on week days (Monday – Thursday) in 2016, people in London used more cocaine than in any of the other 60+ cities where wastewater was analysed:
On the weekend, cocaine use in London was recorded as second highest only to Antwerp:
The fact that SCORE uses a standard protocol and a common quality-control exercise in all locations, making it possible to directly compare illicit drug loads in Europe over a one-week period over six consecutive years. The fact that the data are being published more quickly every year (in this case 9 months after the initial wastewater monitoring) makes the information more useful to policy-makers and treatment agencies.