In an annual European-wide effort (involving engineers, chemists, epidemiologists and statisticians), researchers have been trying to work out which drugs are being taken and where – by testing wastewater in 59 cities across Europe.

Earlier this month, the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) published the results of their latest study. And oh boy, are these guys are committed to rifling through your piss: over one week last March they sampled an estimated 43 million people's wastewater. They were trying to work out geographical drug trends by measuring how many milligrams of a substance they find per 1,000 inhabitants per day. But not all drugs can be accurately tested this way – this method is more accurate for stimulants. So, they just tested for four drugs: coke, MDMA, speed and meth.

Dr Liesbeth Vandam is a researcher at the EMCDDA and has been involved in these wastewater studies since 2013. She reckons this recent study gives some good insight into the current partying habits of Europeans. "This is a rapid information tool," she explained over the phone from her office in Portugal. "The procedure goes relatively fast, and last year we published the data in the same year that it was actually collected. That is good compared to, say, our General Population Survey, which takes a lot more time."

So, what can we learn?

First up, let's look at cocaine. The five cities with the most cocaine use in relation to their population are:

1: Barcelona, in Spain;

2: Zurich, in Switzerland. Who knew;

3: Antwerp Zuid, i.e. only the southern part of the Belgian city;

4: Geneva – again, in Switzerland, wow;

5: Bristol, meaning the UK has a new cocaine capital; until now, London wore the crown.

Usage is up all across Europe, and as VICE reported recently, quality is way up: in the UK, purity can be as high as 80 percent, thanks largely to 2015 legislation that introduced harder penalties for the possession of large amounts of traditional cocaine cutting agents.

"One thing that we saw this year – and we noticed this with indicators in other types of studies, too – was the increase in cocaine use across Europe," says Vandam. "This study has been taking place since 2011, so when we compare the current data with that from previous years we can see a clear increase in 2016. That continued in 2017."

As with any research method, the wastewater approach doesn't come without its own set of limitations.

"With cocaine, we look for the main metabolite [a substance formed by your body as it breaks down coke]. But with MDMA we can’t look for the metabolite, so we look for the actual MDMA," says Vandam. "The problem with that is, with MDMA, the researchers can't be sure whether the result is from human consumption or, for example, production waste. If, in an [underground] lab, someone flushed waste product down the toilet, we wouldn’t know if that was from human consumption or not. Especially in parts of Belgium or the Netherlands, where we know that there is a lot of synthetic drug production. Given the fact that three cities in the Netherlands were in the top five for having MDMA in their wastewater, and that Netherlands is a source country of MDMA, that could be an important point."

Photo: Michael Segalov

Talking of MDMA, the findings of this study confirmed what we already knew: it has made a huge comeback in recent years. Sharp increases, from 2011 to 2016, were observed in most cities tested. Your MDMA league table:

1: Amsterdam, in the Netherlands;

2: Eindhoven, in the Netherlands;

3: Antwerp, in Belgium;

4: Zurich, in Switzerland;

5: Utrecht, in the Netherlands;

"It basically disappeared from the European market in around 2008/09, but we've seen it slowly coming back," Vandam notes. "That was first observed in a wastewater study, then using other monitoring tools. That’s why these studies are important: they give real-time information. Of course, we cannot use wastewater alone, but it's a good indicator."

A strength of this research method – as opposed to asking people what drugs they take in a survey – is that testing the water means we can get a fuller picture of what people are taking, rather than what they think they’ve been taking.

"The users are not always aware of the substance they are taking," Vandam points out. "For example, people can't be sure that there is MDMA in an ecstasy tablet that they buy on the black market. But with testing like this we can be sure if people are actually taking MDMA." It's also feasible that people could lie in a survey, or just not be able to remember what they took – unless they're lucky enough to live somewhere like Amsterdam, where you can get your drugs tested for strength and purity before you take them.

Speed was a mixed bag, with its use varying quite a bit across locations, but had the highest detection levels in Western Europe. The league table:

1: Eindhoven, in the Netherlands;

2: Antwerp Zuid, in Belgium;

3: Saarbrucken, in Germany;

4: Oostende, in Belgium;

5: Mainz, in Germany.

For anyone who's ever stepped into a German nightclub, the fact the country crops up twice in the top five will be entirely unsurprising.

Meth – speed's darker cousin – isn't something we see that much in the UK, is it? It picked up some popularity in the chemsex scene, which is tiny relative to the general drug-taking population, but as VICE reported in 2014, hysterical claims of "the UK's crystal meth boom" were plainly untrue. The findings of the study indicate that this is much the same throughout Europe, where meth use is generally low. But its use on the continent could be slowly changing.

"Another trend we've seen continue over a few years is with methamphetamine," says Vandam. "It has always been prevalent in places like Czech Republic and Slovakia, but it is now appearing in other cities in northern Europe and in cities in East Germany that are closer to the border with the Czech Republic."

The top five cities for meth were:

1: Chemnitz, in Germany;

2: Erfurt, in Germany;

3: Budweis, in the Czech Republic;

4: Brno, in the Czech Republic;

5: Dresden, in Germany;

With the UK only appearing in one top five, it seems that we might not be getting on it as much as our European counterparts. Mind you, only two British cities – London and Bristol – were included in the study, leaving a bunch of UK party hubs out of the equation. Also, the study can't provide any insight into the frequency of drug use in each city studied, only the amount of byproduct in the wastewater.