By conducing chemical analyses of sewage in 19 European cities, scientists show a new picture of drug use across the continent. ScienceNOW explains.
Surveys and data from police and customs are routinely used to put figures on illicit drug use. "The surveys tell you what people take, but not how much, not how big the market is," says study researcher Kevin Thomas at the Norwegian Institute for Water Research. "Sewage tells you that."
For a more accurate and objective method, the researchers looked for chemical traces of drugs and metabolites created when drugs pass through the body.
During one week in March of last year, they collected daily samples representing 24 hours of sewage flow from 21 sewage treatment plants in 19 cities across Europe. The samples were analyzed for traces of different drugs.Here’s a snapshot:
- Cannabis consumption appeared to be similar throughout Europe.
- Cocaine use per capita was highest in Belgium and other parts of west and central Europe, but lower in the north and the east.
- Ecstasy use was also highest in the Belgian city of Antwerp, London, and cities in the Netherlands.
- More residues of both drugs could be found during the weekend.
- Methamphetamine levels per capita were highest in Scandinavian cities and Budweis in the Czech Republic.
- Overall, around 355 kilograms of cocaine was used in Europe every day during the week of the study.
Samples have been collected for at least one U.S. city, and the results will be presented in 2013.
This work was published in Science of the Total Environment.
Image: cocaine / U.S. Drug Enforcement Administration