WHICH city uses more cocaine: Los Angeles or London? Is heroin a big problem in San Diego? And has ecstasy emerged in rural America?
Environmental scientists are beginning to use the bottom line - raw sewage - to paint an accurate portrait of drug abuse in communities. Tests at municipal sewage plants in many areas of the United States and Europe have detected illicit drugs such as cocaine, methamphetamine, heroin and marijuana.
Law enforcement officials have long sought a way to come up with reliable and verifiable calculations of narcotics use, to identify new trends and formulate policies. Surveys, the backbone of drug-use estimates, are only as reliable as the people who answer them. But sewage does not lie.
Since people excrete chemicals in urine and flush it down toilets, measuring raw sewage for street drugs can provide quick, fairly precise snapshots of drug use in communities, even on a particular day.
The results have been intriguing: methamphetamine levels in sewage are much higher in Las Vegas than in Omaha and Oklahoma City. Los Angeles County has more cocaine in its sewage than several major European cities. And Londoners apparently are heavier users of heroin than people in cities in Italy and Switzerland.
"Every sample has one illicit drug or another," said Jennifer Field, an environmental chemist at Oregon State University who has tested sewage in many US cities. "You may see differences from place to place, but there's always something."
The new practice has illuminated an environmental threat. Many urban waterways around the world are contaminated with low doses of cocaine and other illicit drugs from treated sewage.
So far, this "sewage forensics" or "sewage epidemiology" has not been widespread. Treatment plants do not regularly monitor sewage for street drugs. Unlike prescription drugs and personal care products, which are a hot topic in environmental contamination, illicit drugs have long been below the radar.
Christian Daughton, chief of environmental chemistry at the Environmental Protection Agency's national exposure research laboratory, first proposed the tests in 2001. Although initially interested in the environmental ramifications, he realised that the data could help law enforcement, sociologists and others trying to gauge trends in drug abuse.
Scientists in Italy, led by Roberto Fanelli and Ettore Zuccato, were the first to implement his idea, testing sewage in Milan, London and Lugano, Switzerland in 2005.
Amphetamines, including ecstasy, were the least prevalent drugs in the three cities, while marijuana was widely detected, the Mario Negri Institute for Pharmacological Research reported last month in the online version of the journal Environmental Health Perspectives. For every 1000 people, about 210 milligrams of heroin were used daily in London, compared with 70 in Milan and 100 in Lugano. Amphetamine use also was higher in London.
The scientists were even able to use sewage to estimate individual use and weekly trends. For instance, they estimated that in Milan, cocaine use peaked on Saturdays, while heroin and marijuana use remained steady week-long.
For now, this new drug test remains anonymous. Waste water from thousands, sometimes millions, of people is pooled at treatment plants, so it cannot be tracked to any individual or specific location. But because waste also can be tested in local sewers, questions about privacy have been raised.
"You could take this down to a community, a street, even a house," Mr Daughton said. "It's sort of unlimited."
LOS ANGELES TIMES
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