Sifting through sewage to find traces of illicit drugs is no one's idea of fun. But leading experts, meeting in Lisbon, say drug wastewater analysis will shape future public health initiatives.
Most people would refuse to do it. But for a group of leading experts, who have been meeting in the Portuguese capital this week, drug wastewater analysis is an exciting and "rapidly-developing scientific discipline" that may help shape the way we treat illicit drug use.
Drug wastewater analysis - which is also known as "wastewater sampling for drugs" - involves the analysis of human waste, usually at sewage treatment plants.
It has been trialed in at least 19 European countries. And the experts say it can provide reliable data on what drugs are being consumed, where they are being consumed, and even on which days of the week.
"What the technique looks for is drug residues and - more importantly - the metabolites of drug residues," says Paul Griffiths, scientific director at the European Monitoring Centre for Drugs and Drug Addiction, the European Union's drug agency, which co-organized this week's event.
"And the metabolites are important," says Griffiths, "because it means we know the drugs have been consumed by a human being, and therefore they haven't just been dumped into the environment."
The method was originally used in the 1990s to monitor the environmental impact of liquid household waste.
Tracking fast trends
But scientists now say the method is giving them a clear picture of the quantities of illicit drug use in any given population, and drug flows - which means they can tell where illegal drugs are entering the European market.
"We're interested in what's happening in cocaine patterns and we can look to see whether cocaine is appearing in parts of eastern Europe, which hasn't been seen previously, so it's a very fast technique to look a trends," says Griffiths. The issue of speed is an important one.
Public health official often know which drugs are being consumed, and where and when. So, they will usually know if there is a higher use of "club drugs," such as Ecstacy or MDMA.
But Fay Watson, secretary general of the non-profit advocacy body Europe Against Drugs (EURAD), says it is harder to detect new drugs as quickly as they come onto the market. And this is another area where wastewater analysis can help.
"Drug use changes very fast - it's not like alcohol or tobacco use," says Watson. "Drug trends change very, very quickly, and we've got a lot of new drugs on the market now, which aren't really being used by a lot of people, but they are being used by a significant minority."
"So, the wastewater analysis can very quickly pick up new drug use - and how those drugs are being used, which might take a bit too long to come through on a survey," says Watson.
Public health intelligence
One thing drug wastewater analysis can't do is explain why particular illicit drugs are being taken - and how addicted people are to them.
But knowing which drugs are being used in any given area can help public health workers target their programs at specific groups of people and the specific drugs they are using.
"At the local level, I'd be looking at whether I could target specific clubs or areas where people are actively using drugs together to promote the use of drug services, and making sure the local drug services are able and capable and well trained in those types of drugs," says Watson. "And also make sure that your prevention messages are about those particular drugs which are being used in that community."
Last year saw the first big study on drug use in Europe, based on wastewater analysis. It compared 19 European cities, highlighting that the continent's port cities have remained major drug centers. It revealed the highest levels of cocaine use were in Antwerp, Amsterdam and Valencia. The highest levels of amphetamines and methamphetamines were in the Finnish capital Helsinki and Eindhoven in the Netherlands.
Now, a year on, wastewater analysis experts are pushing for the method to gain greater recognition.
"The technique has gone from an interesting, experimental method to something that we can now say is going to make a major contribution to monitoring drug trends," says Griffiths.
Drug wastewater analysis may also have had to overcome "misconceptions" about privacy issues - and skepticism on the part of public health policymakers.
"I think there were some poor studies and poor reporting of studies, which colored political opinion a bit," says Griffiths. "People were quite nervous about it. There was a whole worry about people feeling they were being spied on through their toilets. But this is really about anonymous screening and about identifying problems. And people are beginning to understand that some modern scientific developments do allow us to do things that in the past were simply impossible. So, the next step is to put this together with the policy questions - what do policymakers want to know that this sort of analysis can answer."