Drug abusers may lie, but their body chemistry doesn’t. In what may be the largest urine drug test in history, Italian pharmacologists sampled the country’s longest river, the Po, which bears the sewage of 5 million people. They found that the waterway carries the equivalent of 8.8 pounds of cocaine—or 40,000 individual hits—each day. That is considerably more than previous official estimates, based on surveys that showed 15,000 people take the drug at least once a month.
“When we had the data, we were quite surprised by the amount,” says Roberto Fanelli, one of the study’s authors and head of the Department of Environmental Health Sciences at the Mario Negri Institute for Pharmacological Research in Milan. “A significant part of the population is making constant use of the drug.”
Fanelli believes his work could lead to better drug-law enforcement and abuse prevention: “You could concentrate the investment in those parts of the country where you find evidence of increased traces of drug abuse.” The researchers must validate the study with more data as well as calculate how much cocaine and its metabolite are lost along the way. This would lead to a more precise figure, Fanelli says. “We think the value we had, especially for the river, is underestimated.”