foraged Germany's rivers for a substance produced by the human body during cocaine consumption, and the results were bountiful. The extrapolated numbers revealed, among other things, that residents around the river Rhine's drainage basin near Düsseldorf consume roughly 11 tons of cocaine each year. The street value: around 1.64 billion.
Now the experts at Nuremberg's Institute for Biomedical and Pharmaceutical Research (IBMP) have expanded their method to other EU countries and the US. The results are similar to those of 2005: Previous official estimates for cocaine use, which rely heavily on police statistics, are apparently way too low.
For example in New York, IBMP teams searched the Hudson River and found the by-products of a projected cocaine consumption totaling 16.4 tons per year. There are approximately 3.4 million people aged 15 to 65 living in the Hudson's watershed. According to the United Nations "World Drug Report," 2.8 percent of Americans in this age group use cocaine at least once a year. That would mean that about 95,000 people are responsible for an annual consumption of 16.4 tons of pure cocaine -- a per capita rate of 172 grams per year.
But the "World Drug Report" says the average user, at least in Central and Western Europe, consumes only 35 grams of pure cocaine per year. Unless the appetite of the average American is considerably greater, present estimates of overall consumption are likely to be too low. Either there are more coke-heads than reflected by the official statistics, or they snort far more Charlie per year than yet realized.
And there's more. IBMP Director Fritz Sörgel says there are a number of further lessons provided by his study:
The details vary, though, from city to city. In Washington's Potomac, IBMP chemists found traces of an annual per capita consumption of 73 grams of cocaine, while the San Francisco Bay indicates an annual use of little more than 40 grams per person.
In Europe, the pattern is similar. According to current estimates by the European Union, about 1 percent of Germany's 18 to 59-year-old population consumes cocaine at least once a year. Based on the IBMP measurements, that would mean that the average cocaine user in Nuremberg consumes a mere six grams per year, while in Mannheim the number is closer to 55 grams.
Fritz Sörgel, the director of the IBMP, says the significant discrepancies between individual measurements are the result of two factors. First, the researchers obtained their samples on different times of the year and at different times of the day. Second, the measurements were not always performed at the same distance to the sewage works. They did not take the samples directly at the purification plants, where the by-product benzoylecgonine is broken down by about 80 percent, but instead examined the water after its discharge back into the river. Depending on the distance to its point of re-entry, the water from the sewage treatment plant is more (or less) diluted by the rest of the river water.
"Reliable Overall Picture"
"But the multitude of measurements at different seasons and times of the day and at different distances to the points of entry should result in a reliable overall picture," says Sörgel. Furthermore, the results in the US, Germany, Spain, Italy, the UK, the Netherlands, Austria and the Czech Republic roughly mirrors established country rankings.
"We are not yet dealing with an established scientific method for the exact determination of national cocaine consumption," Sörgel stressed in an interview with SPIEGEL ONLINE. His team is merely taking first steps to provide a scientific basis for the current surveys.
Indeed, an opportunity to compare results is not far off: the European drug administration EMCDDA will present its latest annual report in Brussels on Thursday. But such estimates based on polls have one crucial weakness: Since cocaine is an illegal drug, the results from voluntary surveys are usually skewed well below reality. Heavy consumers in particular are difficult to reach with this method and show "a tendency to understatement," writes Germany's Federal Office of Criminal Investigation (BKA) in its "2004 Federal Situation Report on Narcotics." Authorities should therefore expect "a not insignificant understatement of the actual numbers" in such surveys.
How big? The answer may be in the rivers.
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