• 08.21.12

Mapping Cities’ Drug Problems From Their Sewage

To correctly focus drug enforcement and treatment, it’s important to know how many people are doing drugs and what drugs they’re doing. The problem is that people don’t like sharing that information. But they can’t help what they put in their toilets.

Dr. House was convinced that all patients lie. As it turns out, cities are finding the same thing to be true with drug use within their limits.


In the past, municipal governments have used questionnaires to determine which drugs were being used–and abused–by their citizens. That information helped them develop plans for things like drug enforcement and rehab programs. Now, cities are increasingly turning to an unlikely source of data for answers: sewage. Scientists have made direct comparisons of illicit drug use in 19 European cities by a cooperative analysis of raw sewage samples.

Researchers collected daily sewage samples representing 24 hours of flow from treatment plants in large European cities and analyzed them for the urinary biomarkers of cocaine, amphetamine, ecstasy, methamphetamine, and cannabis. The total amount of the drugs used by inhabitants of each of the cities was measured and the results were adjusted for population size, according to the researchers. The results were released last week in the journal Science of the Total Environment.

Their findings? Drug use has certain patterns across Europe: Cocaine use was higher in Western and Central Europe and lower in Northern and Eastern Europe. High per capita ecstasy loads were measured in Dutch cities, as well as in Antwerp and London. In general, cocaine and ecstasy loads were significantly elevated during the weekend compared to weekdays. Per capita loads of methamphetamine were highest in Helsinki, Turku, Oslo, and Budweis (in the Czech Republic), while the level of cannabis per capita were similar throughout European cities.

The researchers said that sewer-based drug measurements are an important addition to the methods that exist today. “Through sewer research, we can determine how big the drug market in a city is. We can also quickly measure changes in consumption over very short time, such as after a police raid or a customs seizure,” said Kevin Thomas, who coordinated the project as part of the Norwegian Institute for Water Research in Oslo, in a press release.

The researchers speculate that some of the peaks may be due to drug production instead of consumption, or that spikes in certain drugs could coincide with large amounts being flushed down the toilet instead of moving through people’s bodies. U.S. cities will be part of the follow-up research, and the results are expected next year. In 2008, researchers found higher levels of methamphetamine levels in sewage in Las Vegas than in Omaha and Oklahoma City. Los Angeles County had more cocaine in its sewage than most European cities. You can try to hide your drug use, but the truth is in your toilet.