Cocaine typically goes up your nose. It does a lot of stuff once it's inside your body, like raising your heart rate and blood pressure and creating a burst of energy and euphoria. But then, after the effects die down and your body processes the drug, it goes out the other end. As a result, the wastewater drug users flush down the toilet can contain traces of cocaine – and methamphetamine and cannabis and ecstasy and all kinds of other drugs, depending on habits.
When all the collective flushings of a city's drug-using populace combine in the bowels of the sewer system, a citywide drug profile develops. A new technique has been tested out to read and compare those drug profiles, creating an innovative way to understand and monitor the drug-using habits of different urban populations.
The technique is laid out in a new study in the August 15 issue of the journal Science of the Total Environment. Researchers from universities and institutes across Europe teamed up to sample the wastewater in 19 different cities for one week in March 2011 in order to develop a continent-wide comparison of drug usage. They monitored the wastewater for cocaine, amphetamine, ecstasy, methamphetamine and cannabis by identifying traces of the drugs – the same "urinary biomarkers" for which some employers test. Based on the amounts observed, the researchers can determine the per-capita usage in cities of each of those drugs.
According to the paper, distinct spatial patterns can be detected for drugs. Cocaine, for example, was used much more in Western and Central Europe than Northern and Eastern Europe. Ecstasy was most popular in Dutch cities, as well as London and Antwerp. Methamphetamine use was highest in the Finnish cities of Helsinki and Turku, as well as Oslo, Norway, and Budweis, Czech Republic. Cannabis use was relatively similarly across the 19 test cities.
The researchers also found that certain drugs were being used more often on the weekends. While that may not be too surprising, the technique opens some new avenues for understanding drug use and how it varies dramatically from city to city and over time.