top of page

Monitoring Drug Use through Sewage: A Helpful Supplement?

Updated: Aug 30, 2023

Editor’s Note: Today we welcome guest blogger Toine Pieters, senior lecturer and researcher at the VU-Medical Center in Amsterdam (since 1998) and professor of the History of Pharmacy at the universities of Groningen and Utrecht (since 2008). Working at the intersection of psycho-pharmacology, addiction studies, genetics and eugenics, he is the author of Interferon: The Science and Selling of a Miracle Drug (London, 2005) as well as a host of diverse papers. In addition to teaching and writing, he also is the project manager of WAHSP and BIland: Web applications for historical sentiment mining in public media.  Pieters will be guest blogging at Points intermittently through the fall– we hope with a whole slate of provocative topics like today’s.

Archaeologists love to dig into trash as a source of information for reconstructing the past. Biochemical researchers have followed suit with another kind of waste: sewage.

Sewage Epidemiology

Over the past decade a new promising technique based on the analysis of urinary drug biomarkers in sewage has been developed to estimate drug use by specific populations. This approach has been referred to as ‘sewage epidemiology’. Throughout last year, researchers from 19 different European countries studied illicit drug use by chemically sifting through the sewers. What does the study tell us about monitoring drug use?

The claim is that screening for drugs that pass through the body and then get flushed down the toilet is a faster and more reliable way to assess a community’s drug use than the time consuming data gathering tools currently available: population surveys and indirect estimates of drug production and seizure. The major assumption is that a sample of waste water is representative of a pooled urine sample of the entire population in the study area. The idea is that the data about what goes into the sewers are far more difficult to manipulate. A prerequisite for a reliable measurement is that the waste water samples are collected in such a way that they accurately represent the total volume of sewage from the entire day irrespective sleep wake patterns, commuter behavior, population changes or drug use patterns (weekend use only, or habitual).

In the European study, published online in the journal Science of the Total Environment,Kevin Thomas, Lubertus Bijlsma, Sara Castiglioni and others performed sewage analysis simultaneously in 19 European cities across Europe—from Antwerp to Zagreb–over a single week. The samples were analyzed for traces of five different drugs (Cocaine, MDMA, AMP, Meth and cannabis) by local labs according to a fixed protocol. They found some interesting results. Cocaine use per capita was highest in Antwerp and other cities of Western and Central Europe, but lower in Northern  and Eastern Europe. Ecstasy use was also highest in the Belgian city of Antwerp, London, and cities in the Netherlands. Meanwhile, methamphetamine levels per capita were highest in Scandinavian cities. Thus, the study seems to provide an interesting weekly snapshot of drug flow through the European cities  in March 2011.

Antwerp: Tops for Cocaine and Ecstasy

However, despite the optimistic sound bites in newspaper headlines and radio/tv coverages recently (e.g. “For the first time in history, scientists have now made accurate measurements of illicit drug use in 19 European cities”) we should be cautious in replacing conventional drug data gathering tools overnight.

Some of the observed drug sewage peaks may be due to drug production rather than consumption, however. For instance, sewage from cities in the Netherlands and Antwerp in Belgium showed high levels of amphetamines, but previous surveys suggest the use of those drugs is actually two to three times lower there than in the rest of Europe. Some of the substances may get into the sewer system from illicit drug production laboratories which cluster in the region. And a spike in the ecstasy load in Utrecht, the Netherlands, is most likely due to a drug bust that coincided with the testing period and drugs being flushed down the toilet before the police arrived.

New Kid on the Block

This all shows that monitoring illicit drug use needs further work and requires triangulation with conventional data gathering methods. Thus, the application of sewage analysis should be regarded as a valuable addition rather than a replacement of the data gathering tools currently available.


Recent Posts

See All


bottom of page