Your Sewer on Drugs

Sewage is more than just filth. It’s evidence of our worst habits, everything from caffeine to cocaine, all ingested and flushed down the toilet. Now scientists are using wastewater to drug-test entire cities, and the results are sobering

Jorg Rieckermann snaps on a pair of purple rubber gloves, picks up a crowbar, and levers a manhole cover out of the way. “Here’s my access to the underworld,” Rieckermann, who speaks with a faint German accent, says as he hoists up a barrel-shaped robot suspended above a stream of raw sewage. Rieckermann’s protective gloves and orange jumpsuit are a sharp contrast to the parched brown backdrop of San Diego. But there’s no guarding against the stench. I can almost see the vapor, a rank blend of excrement and vomit that hits me like nuclear-strength smelling salts. If hell has a smell, it has found its way to this suburban portal, sandwiched between train tracks and a highway just outside the city limits.

Rieckermann seems unfazed. Moving with hunched urgency, the athletic 34-year-old pops open the top on the corrugated-plastic robot. The contraption uses a vacuum pump and a long hose to siphon samples from the sewage and then fill a carousel of plastic flasks with a mechanical arm. Apparently the battery has died, because half the flasks are empty. “At least it didn’t malfunction and overflow, like last time,” Rieckermann says, adjusting his rimless eyeglasses. He punches a keypad to recalibrate the draw. The robot beeps and gurgles and then spits up 100 millimeters of brown water. “Now, that’s a nice sample,” he says, holding up a plastic test tube full of sewage to the morning sun. “Liquid, plus particles—toilet paper, feces, sludge, slime.” Not to mention traces of cocaine, methamphetamine, marijuana, heroin and any number of other illicit substances ingested, digested, and then flushed down the toilet. This spiked refuse is why we’re here.

Rieckermann, a Swiss-trained environmental engineer, is one of a handful of scientists in the world pioneering a controversial new field known as sewer epidemiology, whose goal is to provide the first truly objective estimate of illegal-drug consumption. He’s now visiting San Diego State University on a research fellowship from the Swiss National Science Foundation to develop a mathematical model of community drug use based on the amount of illicit by-products that wind up in the sewers.

The approach is, in essence, a community drug test. By analyzing wastewater at treatment plants or at strategic spots throughout sewer systems, scientists can run extraordinarily accurate and anonymous tests on an entire population without ever asking anyone to hand over a cup of urine. (Everyone has to use the toilet, after all.) If, say, Philadelphia implements an ad campaign against methamphetamine, officials could gauge levels of the drug in the wastewater to instantly see if it’s working. Maybe San Francisco is considering building methadone clinics—does the data suggest they’re worth it? And if law enforcement wants to know whether drug busts are reducing consumption in certain neighborhoods, it could get an immediate answer.

Supporters say that wastewater testing provides objective data that links the hard science of chemical analysis and the social science of epidemiology. Conducting a urinalysis of an entire city, they argue, could be far less expensive and time-consuming than surveys, which can take up to a year to process. It would give officials the ability to study drug use in cities and towns in nearly real time.

What’s in a drop of sewage? What’s not? Find out in our photo gallery here. And for the down-and-dirty story behind the story from author Eric Hagerman, check out the first episode of our Cocktail Party Science podcast.

That is, if municipalities will allow it. Back at the sewer, Rieckermann is struggling to lower the 25-pound robotic sampler into its foul-smelling hole. “It’s not that I like this,” he says. But he has no choice. San Diego officials balked at his plan to drug-test their city, so instead of simply receiving samples at the lab from wastewater technicians, who routinely collect them to monitor for environmental pollution, he’s schlepping to the city’s outskirts every day. It’s unclear whether city officials fear the prospect of San Diego’s drug problem coming to light—Heather Lade, the wastewater department’s public-information officer, would only say, “We’re not interested in implementing the program because we have other operational priorities.”

Rieckermann is the first to point out that the methodology of sewer epidemiology needs work. It’s based on assumptions that range from what constitutes an average dose to how often people urinate to how many tourists and commuters might be adding to the soup. And although it’s possible to calculate the total amount of a drug consumed, it’s still difficult to nail down the percentage of users within a population. “If you have five junkies in the catchment, do they compensate for, like, 100 users?” Rieckermann asks. As he has already discovered, there are other sticky questions, both scientific and ethical, about whether these methods can be implemented on a scale large enough to be useful. No city wants to be known as the coke capital of the world, and some critics fear Big Brother tapping their plumbing as well as their phone line. But Rieckermann wouldn’t be mucking around in all this if he didn’t think it held great promise.


Today’s drug-abuse estimates are based almost entirely on surveys. Interviewers knock on the doors of a random sampling of people and ask if they wouldn’t mind sharing details about their drug habits. The Substance Abuse and Mental Health Services Administration (SAMHSA) spends about $40 million a year on its National Survey on Drug Use and Health—the gold standard for epidemiologists—primarily for the expense of sending 600 to 700 interviewers out to canvass for people who will talk. The response rate is surprisingly good, at about 70 to 80 percent, but among the inherent limitations of surveys is the subjectivity of the answers, especially when the topic is illegal activity. “The more sensitive and deviant the behavior, the more likely it is to be underreported,” says Joe Gfroerer, who oversees the survey division at SAMHSA.

Public-health officials also look at emergency-room visits, police seizures and autopsy reports to piece together a more complete picture of drug use, but these numbers are small and don’t necessarily allow for comparisons from one place to the next. For instance, one sheriff’s department may lump heroin and cocaine into the same category, while the next county over separates the two.

Yet this patchwork portrait is the current basis for identifying epidemics and establishing prevention and treatment programs. It also determines how the government parcels out billions of dollars in funding for the war on drugs. “Essentially, all we have is surveys,” says David Murray, a former special assistant to the drug czar and the chief scientist of the Office of National Drug Control Policy, the arm of the White House that runs drug-control initiatives. The federal assessment of drug use in the U.S. is based, at best, on incomplete information.

But there’s no question that America has a serious drug habit. SAMHSA’s nationwide survey indicates that 20.4 million Americans aged 12 or older, or 8.3 percent of the population, were illicit-drug users in 2006. An estimated 14.8 million people admitted using marijuana in the month preceding the survey, making it the most popular drug; roughly 2.4 million people say they use cocaine, and 731,000 people admit to methamphetamine use.

Worse still, those figures almost certainly underestimate the problem. In 2005, Italian environmental chemists Ettore Zuccato and Roberto Fanelli of the Mario Negri Institute for Pharmacological Research in Milan, pioneers in the field of sewer epidemiology, drug-tested Italy’s Po River and several wastewater-treatment plants for benzoylecgonine, the main by-product of cocaine. In the end, they estimated that the equivalent of four kilograms of the drug and its by-product flow through the Po every day. That works out to be about 40,000 doses, each about 100 milligrams, roughly equivalent to a pinch of sugar. If consumption were evenly distributed among the river basin’s 1.4 million people aged 15 to 35 (the typical user), about 2.7 percent of them use cocaine. This figure is more than double the official estimates from drug surveys of Italy in 2001, the most recent available. But the researchers met resistance when they shared their results with government drug agencies. “Nobody wanted to believe it,” Fanelli says.

Perhaps even more compelling is what they found in Milan. After several months of drug-testing the city’s sewage, they discovered that although cocaine use spikes during the weekend, as expected, levels are still significant on the weekdays, which suggests that people use the drug not only recreationally but also habitually. Since then, Zuccato and Fanelli have widened the net to track other drugs. Their results estimate that the presence of amphetamines in Milan has doubled or tripled in the past several years, while heroin use—contrary to survey results—has dropped considerably.

The researchers were invited to Lisbon, Portugal, last spring by the European Monitoring Center for Drugs and Drug Addiction to flesh out their methodology with five other scientists. Rieckermann attended, along with local experts in metabolism, epidemiology and disease-mapping. Collectively, they produced a white paper on the subject, which the EMCDDA intends to publish this spring. The hope is that the agency will follow up with funding for a formal monitoring system in a number of major European cities. “We need to have more data,” Fanelli says. “We’d like to have a full year covered, day by day.”


It was Christian Daughton, chief of environmental chemistry at the Environmental Protection Agency, who laid the groundwork for sewer epidemiology. In 1999 Daughton published a landmark paper documenting what happens to personal-care products and common prescription drugs such as birth-control pills when we pass them through urine or just flush them whole. All the potions and lotions we use, he concluded, end up in our rivers and drinking water. His interest was in the resulting pollution, but the finding held larger ramifications: The life of a drug persists long after we ingest it.

In 2001 Daughton proposed the novel idea of testing for illicit drugs in wastewater. After all, he said, “chemicals are chemicals,” and whether they come from bug spray or dime bags, they affect the environment. In 2004 the EPA followed up on Daughton’s proposal and tested effluent from three wastewater-treatment plants. The study, published in an environmental journal, revealed significant levels of methamphetamine and Ecstasy in the samples. But the EPA was less concerned about where the drugs came from than where they were going, namely, into marine life and drinking water.

Sewer epidemiology stalled stateside until 2006, when environmental chemist Jennifer Field of Oregon State University hit upon the idea as a way to help assess Oregon’s growing meth problem (state officials reported 90 meth-related deaths in 2006, up from 56 in 2000).

Field read up on Zuccato and Fanelli’s work and began conducting a small proof-of-concept study, analyzing teaspoon-size samples of wastewater from 10 cities left over from an older environmental study. She found that a sample from a popular gambling destination boasted the widest range of drugs, while one from an affluent town tested positive exclusively for cocaine (Field won’t disclose the cities’ names). Her team made headlines last August when they presented these and other findings at the American Chemical Society meeting in Boston. Their results—similar to those of Zuccato and Fanelli—showed cocaine levels highest on the weekends, while levels of methamphetamine remained constant. “Once you’re hooked, you’re hooked,” Field points out.

Today, Field is heading up the most ambitious community urinalysis test yet. She’s soliciting wastewater samples from 130 treatment plants throughout Oregon, which service approximately 80 percent of its 3.7 million residents. Her aim is a high-resolution snapshot of drug use from a broad swath of the population during a single 24-hour period, sort of a day in the drug-using life of the state. Oregon Health Sciences University, which is footing the $30,000 bill through its Medical Research Fund, stands to gain a trove of data about drug use in individual communities, since Field will have direct estimates from areas in which surveyors have surely never set foot.

Beyond shedding light on where the state’s pervasive methamphetamine epidemic is worst, Field is tackling the logistical issues necessary to implement wastewater testing on a large scale. It will require every ounce of the compact 45-year-old’s considerable energy to pull it off. Her immediate objective, when I visited last November, several weeks before she sent out sampling kits to the wastewater plants, was figuring out how to manage the multitude of deliveries. Piled high on her filing cabinet were boxes of Ziploc bags, plastic bottles, paraffin and absorbent pads that she acquired from the university’s environmental-health department. She hopes the wastewater technicians will follow her instructions to double-bag the samples. “Leaky boxes make the U.S. Postal Service very nervous,” Field says. A spilled sample would attract unwanted—and, she argues, unnecessary—attention. “There’s something nasty in the box,” she acknowledges, “but not so nasty that it needs a warning sticker.”

Raw sewage, Field explains, isn’t considered a biohazard, because it’s too dilute. Nevertheless, it has a life of its own, and it begins changing rapidly at warm temperatures. She can account for drug metabolites biodegrading in the sewer line, but to keep the stagnant samples free of microbes, Field is sending out collection bottles with a few drops of acid, which should protect the samples until she can get them in the freezer.

Once the collection work is done, she’ll test each sample for 17 substances, including methamphetamine, Ecstasy, cocaine and its metabolite benzoylecgonine, as well as the controlled yet often abused drugs oxycodone, methadone, morphine and hydrocodone. In addition, she will look for cotinine, a metabolic product of nicotine, and caffeine, which will help her refine her per-capita estimates by comparing her findings against existing information about the prevalence of these legal products.

Field’s lab is the only one in the U.S. equipped to screen for all these substances in wastewater (she also analyzes Rieckermann’s samples). To pinpoint a drug or its metabolite in a dilute cocktail of everything flushed down the toilet—which could be any combination of the more than 30 million chemicals known to exist—Field employs a liquid chromatograph and mass spectrometer. The liquid chromatograph sorts and separates the molecules, and the mass spectrometer draws them into a vacuum, ionizes them, and identifies them based on their unique mass and structure. The method can identify compounds at a level of nanograms per liter, or parts per trillion. This sensitivity is on the order of spotting a square-foot tile in a floor the size of Indiana.


Taking and measuring the samples is relatively easy. The trick is figuring out how to interpret them. Heroin, for instance, is most easily identified by its metabolite morphine, but morphine itself is also used as a prescription painkiller. So you need precise values for all the morphine prescribed in a given population to be able to subtract that fraction out of the sample. For marijuana, the target molecule is THC, which is tricky in its own right. “There is a wide variation in the amount of active ingredient in grass,” Fanelli says. He relies on average potency, which can be gleaned from pot busts. Sewer epidemiologists must factor in all of these variables.

But assuming they manage to refine their technique, and sewer epidemiology becomes a reliable way to lay bare a city’s sins, what community will subject itself to such revealing scrutiny? One official in Oregon called Field and said his city wouldn’t participate in her study because several medical institutions feed into the treatment plant, and he feared that their contribution would skew the results and tarnish the reputation of his citizenry. And some people worry about how such methods might infringe on their civil liberties. One of the calls Field received after news broke about her proof-of-concept study, for instance, was from High Times magazine. “They wanted to know about privacy,” she says. “We’re interested in municipalities, not individuals. But when you go out and talk about this stuff, you can hit nerves. It opens the question of whose wastewater it is to give away.”

Despite Field’s sincere assurances about anonymity, once the methods of sewer epidemiology are firmly established, they could be implemented by anyone. Law-enforcement agencies could set up a monitoring index and even take samples right up to the curb of your home. Wastewater officials already have the authority to screen the effluent of industry to identify polluters; there’s no reason those samples couldn’t be run for illicit drugs.

Knowing where in the country heroin use is highest, for example, could help Drug Enforcement Administration agents target their investigations or track major suppliers. Local police might be interested in subtler differences. If daily monitoring shows a spike in the standard ratio of cocaine, it means that somebody probably flushed his stash down the toilet. Monitoring day-to-day changes could also turn up clues about the activity of pharmaceutical plants if scientists tested for by-products that they flush.

So far, the Office of National Drug Control Policy is proceeding cautiously. “We’d really like to have something biometric,” David Murray says, speaking about the limitations of drug surveys. “If you’re serious about trying to make a difference, you’ve got to have the best science available to you.” But his office has offered only a tepid endorsement of sewer epidemiology. Field, Fanelli, Rieckermann and Daughton have all received probing calls from the White House about new drug-testing methods. In spring 2006, the ONDCP even conducted a pilot study in which it sampled sewage at 34 plants in various cities. Murray won’t divulge the locations or the findings, but he says that the ONDCP may work with the EPA to implement a strictly voluntary monitoring campaign for cocaine.

But it seems that when the ONDCP calls offering to upend the self-image of a big city with a radical new measurement method, that city recoils. Murray wanted to include San Diego in the pilot study, but the formal request prompted a formal denial from the mayor’s office. Then, when Rieckermann showed up with his modest proposal of a few test sites, he got the same answer.

His results, he freely admits, can be jarring. Rieckermann’s tests offer few excuses, and in the future he will correlate that data with sociological data about income levels and race. And he’s doing it at the neighborhood level, which he believes is the only way to get truly useful information. Of course, whether cities are ready for what Rieckermann finds is another question.

Contributing editor Eric Hagerman is co-author of Spark: The Revolutionary New Science of Exercise and the Brain.