Sewage reveals drug hot spots in Europe

From the biggest-ever drug analysis of samples taken from Europe's sewers, the research team deduced that the continent uses about 350kg of cocaine every day while marijuana remains the most popular illicit drug.

"Through research into the sewer, we can determine how big the drug market in a city is," co-ordinator Kevin Thomas of the Norwegian Institute for Water Research said of the study covering cities in 11 European countries.

The team took samples from the inlets of 21 sewage treatment plants servicing a combined population of some