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 an unsavory new tool -- raw sewage -- to paint an accurate portrait of drug abuse in communities. Like one big, citywide urinalysis, tests at municipal sewage plants in many areas of the United States and Europe, including Los Angeles County, 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, Okla. 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, regardless of location," said Jennifer Field, an environmental chemist at Oregon State University who has tested sewage in many U.S. cities. "You may see differences from place to place, but there's always something."
The new practice of testing sewage 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. The Environmental Protection Agency is planning to add illicit drugs to the array of substances that could be monitored daily at treatment plants.
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 EPA's National Exposure Research Laboratory, first proposed the tests in 2001.
"To me, chemicals are chemicals. All chemicals, whether legal or illegal, have the potential to get into the environment, and living organisms have a potential to be exposed," Daughton said.
Daughton, who was interested in environmental ramifications, realized that the data could help law enforcement, sociologists and others trying to gauge trends in drug abuse.
Most of those experts rely on door-to-door annual surveys, which are based on questioning of 70,000 people nationwide. Based on that, they estimate that more than 20 million Americans used illicit drugs in 2006.
Scientists in Italy, led by Roberto Fanelli and Ettore Zuccato, were the first to implement his idea, testing sewage in London; Milan, Italy; and Lugano, Switzerland, in 2005.
Amphetamines, including Ecstasy, were the least prevalent drugs in the three cities, whereas marijuana was widely detected, the Mario Negri Institute for Pharmacological Research reported in the online version of the journal Environmental Health Perspectives on their work, published last month.
For every 1,000 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 people in Milan used twice as much cocaine, about 35 grams per person per year, than Italy's government surveys had suggested. Cocaine use peaked on Saturdays, while heroin and marijuana use remained steady weeklong.
In the United States, officials at the Office of National Drug Control Policy looked for cocaine in sewage from Los Angeles County and 23 other regions in 2006.
Untreated sewage at all eight treatment plants tested in Los Angeles County contained cocaine metabolite, according to data obtained from the Los Angeles County Sanitation Districts. Palmdale and Lancaster had the highest concentrations, averaging 3.5 parts per billion. The lowest, averaging 1.4 ppb, were from Long Beach and Valencia.
In all the Los Angeles County locations, the cocaine metabolite was more concentrated than in Omaha and in Italian, Swiss and British cities, which all had less than 1 ppb, according to a comparison of several studies.
Other tests have shown that some U.S. cities have a bigger methamphetamine problem than Europe. Within the U.S., Las Vegas' concentrations were five times higher than Omaha's and twice Oklahoma City's, said Field, who conducted those tests.
Comparing cities can be tricky. Concentrations can fluctuate because of volumes of flow, time of day and how long waste travels through sewers, which gives drugs a chance to degrade.
"This has caught on only recently, and people are still trying to understand the uncertainties," said Field, who is currently analyzing data from 96 locations in Oregon.
Jennifer de Vallance, spokeswoman for the White House's Office of National Drug Control Policy, said the testing of sewage in 2006 was an experiment to see if it could provide useful data to federal drug officials at a low cost.
"It came back very favorable. Our determination was that it probably could be done on a larger scale," she said.
EPA Assistant Administrator Benjamin Grumbles said that the EPA and the national drug office are "working on the details" of a voluntary program at sewage plants that will test for illicit drugs.
"This is sensitive for various communities because these substances do have a stigma attached to them," Daughton said. San Diego, for example, refused to grant permission to researchers.
The Sanitation Districts of Los Angeles County don't test for illicit drugs because iDrug Enforcement Administration permits to handle controlled substances would be needed, said supervising engineer Ann Heil.
"It's too hard to test for it. We can't have morphine lying around to calibrate equipment," she said.
Some researchers are now checking the environment for illicit drugs. Traces of prescription drugs have been detected in some drinking water supplies, and cocaine and other drugs have been found in rivers. No one has tested drinking water for illicit drugs.
"Since most of these residues still have potent pharmacological activities, their presence in the aquatic environment may have potential implications for human health and wildlife," the scientists from Milan reported in February.
Although few researchers are studying the effect of these ultra-low doses, scientists say the threat to people is probably minimal. To get a typical dose of cocaine, someone would have to drink 1,000 liters of raw sewage, Field said.
For now, this new drug test remains anonymous. Wastewater 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," Daughton said. "You can do all kinds of stuff with this. It's sort of unlimited."