August 6, 2005
What a Blow: Cocaine Residue in Italian Water Reveals More Users than Official Estimates
The levels of cocaine residue in flowing water in Italy suggest that many more people take the drug than official national estimates previously suggested. A study published today in the open access journal Environmental Health reports on a new tool used to measure the levels of a cocaine by-product excreted in urine, and present in rivers and in flowing sewage water. This new method provides evidence that about 40,000 doses of cocaine are consumed every day in the Po valley - according to official estimates for this area, only 15,000 users admit to taking the drug at least once a month.
Current official estimates for illegal drug use, including cocaine, are based on population surveys, medical records and crime statistics. These methods are known to be unreliable and to under-estimate the extent of illegal drug use, mainly because they rely on users self-reporting drug use, a socially censured behaviour, which users tend to be elusive about.
"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", write Zuccato et al.
Their results demonstrate that new methods are needed to assess the number of illegal drug users. These figures are necessary to follow changes in drug use trends and help tackle drug abuse. Although the new method implemented by Zuccato et al. looks like a promising candidate, the authors warn "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."
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