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 (7 March 2018) by the Europe-wide SCORE group, in association with the EU drugs agency (EMCDDA). The project in question analysed wastewater around 60 European cities and towns (hereinafter referred to as ‘cities’) to explore the drug-taking habits of those who live in them. The results provide a valuable snapshot of the drug flow through the cities involved, revealing marked geographical variations (see the motion graphic below for a full explanation).

2017 key findings

The project revealed a picture of distinct geographical and temporal patterns of drug use across European cities.

The benzoylecgonine (BE) loads observed in wastewater indicate that cocaine use is highest in western and southern European cities, in particular in cities in Belgium, the Netherlands, Spain and the United Kingdom. Wastewater analysis indicates that cocaine use is very low to negligible in the majority of eastern European cities.

The loads of amphetamine detected in wastewater varied considerably across study locations, with the highest levels reported in cities in the north and east of Europe. Amphetamine was found at much lower levels in cities in the south of Europe.

In contrast, methamphetamine use, generally low and historically concentrated in the Czech Republic and Slovakia, now appears to be present also in Cyprus, the east of Germany and northern Europe. The observed methamphetamine loads in the other locations were very low to negligible.

The highest mass loads of MDMA were found in the wastewater in cities in Belgium, Germany and the Netherlands.

Ten countries participating in the 2017 monitoring campaign included two or more study locations (Belgium, Cyprus, Czech Republic, Germany, Finland, France, Netherlands, Portugal, Spain and Slovakia). The study highlighted differences between these cities within the same country, which may be explained in part by the different social and demographic characteristics of the cities (universities, nightlife areas and age distribution of the population). In the large majority of countries with multiple study locations, cocaine and MDMA loads were higher in large cities compared to smaller locations. No such differences could be detected for amphetamine and methamphetamine.

In addition to geographical patterns, wastewater analysis can detect fluctuations in weekly patterns of illicit drug use. More than three-quarters of cities show higher loads of BE and MDMA in wastewater during the weekend (Friday to Monday) than during weekdays. In contrast, amphetamine use was found to be distributed more evenly over the whole week..

Trend data

Twenty-one cities have participated in at least five of the annual wastewater monitoring campaigns since 2011, which allows for time trend analysis of drug consumption based on wastewater testing.

A relatively stable picture of cocaine use was observed between 2011 and 2015 in most cities.. The general patterns detected were similar in the first five consecutive monitoring campaigns, with the highest and lowest BE loads found in the same cities and regions. Most cities show either a decreasing or a stable trend between 2011 and 2015. In 2016, there were initial signs that this pattern was changing with 22 out of 33 cities with data for 2015 and 2016 reporting an increase. This was confirmed in 2017, with 19 out of the 31 cities with data for 2016 and 2017 reporting an increase in the loads found. Most of the 13 cities with data for 2011 and 2017 report increasing longer-term trends. The previous round of analysis found London to be the cocaine capital of Europe. The current study sees higher levels of per person use in Zurich and Barcelona, but this may be partly because there is no updated data for London in 2017.

Over the seven years of monitoring the highest MDMA loads were consistently found in the wastewater of cities in Belgium and the Netherlands. Looking at longer term trends, in most cities with at least six data points wastewater MDMA loads were higher in 2017 than in 2011, with sharp increases observed in some cities, including Antwerp and Amsterdam. For most of those cities that observed sharp increases for the period 2011–16, the trend seems to have stabilised in 2017.

Overall, the data related to amphetamine and methamphetamine from the seven monitoring campaigns showed no major changes in the general patterns of use observed.