Sewage as a Measure of Society's Drug Use

All kinds of people use illegal drugs, all over the country -- in urban, suburban, ex-urban, and rural areas. Yet our imperfect methods for gauging community drug use disproportionately represent cities and often leave out the highest-risk populations, giving a skewed picture of who uses what types of drugs where.

The answer, oddly enough, may reside in shit. After all, everything that comes in must come out, so using human waste as a measure of society's health makes sense.

Drug epidemiologists are particularly excited by a study published last year in the journal Addiction which tested untreated wastewater in municipal plants throughout the state of Oregon for traces of cocaine, methamphetamine, and Ecstasy.

The Oregon study is not the first to test wastewater for drugs, but it's the first to use the methodology to spatially map drug prevalence. And its most exciting result is likely that it shows just how geographically widespread drug use is.

Researchers studied wastewater samples from 96 municipal water treatment facilities throughout Oregon. These represented one-day snapshots of 65 percent of the state's population's sewage. The results show that drugs are found in all sorts of communities -- everywhere from small, rural towns to suburbs and inner cities.

The emergence of drug use specific to small towns and rural areas -- propelled by the use of meth and prescription opiates -- has cemented the geographic and socio-economic universality of illicit drug use. The Oregon data showed more meth was detected in rural areas than in urban cities, while higher traces of cocaine and Ecstasy were found in urban locations.

To folks who study drug epidemiology carefully, these results could prove revolutionary. Currently, we rely on two surveillance systems that are biased toward urban areas. One is the DAWN Program, which monitors drug-related visits to hospital emergency rooms and drug-related deaths investigated by medical examiners, and another is the Arrestee Drug Abuse Monitoring program, a voluntary survey and urinalysis of arrestees.

We also depend on the Treatment Episode Data Set, which pulls drug treatment data from across the country but relies mostly on data from public facilities and is, by its very nature, a lagging indicator. Finally, the big federal surveys -- namely the National Survey on Drug Use and Health -- suffer from response bias and miss many of the folks who are most likely to be using drugs, such as the homeless, hospitalized, and imprisoned.

"Small-town drug usage is a big mystery," says John Newmeyer, a social psychologist in San Francisco who has worked as a drug counselor and first thought of testing sewage water 15 years ago. "So is usage of certain drugs, like MDMA [or Ecstasy] that don't have negative indicators -- like a high number of overdoses or arrests -- and which are very hidden."

But wastewater carries the metabolites of everything you ingest -- so a more accurate idea of the prevalence of drugs like Ecstasy will now be possible. In addition, sewage testing eliminates the urban skew, as the vast majority of the country's waste flows to sewage systems rather than to individual septic tanks. And municipal wastewater includes the high-risk populations that are left out of the other data because their waste flows into the same sewage treatment facilities.

As a result, Caleb Banta-Green, a co-author of the study, said another plus is that "you can measure apples to apples across places. You can't compare places if you're not measuring them in the same way."

But the methodology has its limitations. Though researchers testing the waters of the Po River in northern Italy concluded in 2005 that 1.4 million young adults living in the Po River Basin's watershed were consuming about 40,000 doses of cocaine a day, Banta-Green says such back-calculations are "extrapolations that are speculative at best." The methodology, as it stands right now, he says, can only really accurately measure traces of drugs in certain geographic locations, so you can compare drug trace levels in different areas, but you can't tell how many people are using drugs and at which rate.