5 August 2005

Wastewater Reveals A Cocaine Surprise

by Kate Melville

Law officials and drug policymakers may have to reconsider the methods they use to estimate the number of illegal drug users following some surprising research results from Italy. The levels of cocaine residue in flowing water from the Po valley area suggest that many more people take cocaine than official national estimates had previously suggested. The study, published in Environmental Health, reports on a new method used to measure the levels of a cocaine by-product excreted in urine that is found in rivers and sewage water. The new analysis technique found that about 40,000 doses of cocaine are consumed every day in the area - far in excess of the previously estimated 15,000 users who admitted to taking the drug at least once a month. The methods of estimating drug use in the past have been based on surveys, medical records and crime statistics. These methods are known to be unreliable as they rely on users self-reporting a socially censured behavior.

The new method measures benzoylecgonine (BE), a residue excreted in the urine of cocaine users. The researchers measured the levels of BE in the river Po and in the sewage water of several medium-sized Italian cities. Their results show that the river Po, with five million people living in its vicinity, carried the equivalent of about 4 kg of cocaine per day. The researchers say this translates into a least 40,000 doses being used every day.

Researcher Ettore Zuccato, from the Mario Negri Institute in Milan, said the results were something of a surprise. "Our main goal was initially to verify how our consumption estimates compared with official figures. We expected our field data on cocaine consumption to give estimates within the range of the official estimates, or perhaps lower, but certainly not higher", said Zuccato.

Zuccato added that "clearly, the method implemented here needs to be refined and validated, and adapted for other drugs of abuse before it can become a general tool for monitoring drug abuse." The researchers do conclude however, that in light of these findings, new methods may be needed to more accurately assess numbers of illegal drug users.