Nature: A study of drug chemicals in sewage water suggests that the level of cocaine use could be many times the figure suggested by questionnaires.

Ettore Zuccato of the Mario Negri Institute for Pharmacological Research in Milan and his colleagues took river and sewage samples from four medium-sized Italian cities. They analysed these samples for cocaine and its main metabolite, called bezoylecgonine, which is found in urine. Click here to read the story.