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 week (14 March 2019) 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 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).
2018 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 remains highest in western and southern European cities, in particular in cities in Belgium, the Netherlands, Spain and the United Kingdom. Very low levels were found in the majority of the eastern European cities studied, but the most recent data show signs of increases.
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 Czechia and Slovakia, now appears to be present also in Cyprus, the east of Germany, Spain and Finland. 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.
Fourteen countries participating in the 2018 monitoring campaign included two or more study locations (Austria, Belgium, Cyprus, Czechia, Germany, Finland, France, Italy, Lithuania, Netherlands, Portugal, Spain, Slovakia and Slovenia). 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 amphetamine, BE and MDMA in wastewater during the weekend (Friday to Monday) than during weekdays. In contrast, methamphetamine use was found to be distributed more evenly over the whole week. The project revealed a picture of distinct geographical and temporal patterns of drug use across European cities.
Increased use of cocaine across Europe
Thirty-three 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. In 2018 this increasing trend in use continued, 22 of the 38 cities with data for 2017 and 2018 reporting an increase. Increasing longer-term trends are reported for most of the 13 cities with data for 2011 and 2018.
Bristol was the city with the highest mean amount of cocaine biomarker in its wastewater relative to its population with a “score” of 969.2 mg/1000 people per day compare to 932.4 for Amsterdam and 856 for Zurich, the cities with the next highest levels. Of course, Bristolians may use less cocaine than London or other UK cities but it is the only UK city where the wastewater project currently operates.
MDMA use up too
Over the eight 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 2018 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. However, the most recent data in 2018 point to increases in most cities.
Overall, the data related to amphetamine and methamphetamine from the seven monitoring campaigns showed no major changes in the general patterns of use observed. Looking at the most recent data however shows that of the 38 cities with data for 2017 and 2018, 21 reported an increase for amphetamine, with the loads found being higher during weekends.