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Sewage tells tales about community-wide drug abuse

August 22, 2007

Public health officials may soon be able to flush out more accurate estimates on illegal drug use in communities across the country thanks to screening test described here today at the 234th national meeting of the American Chemical Society, the world's largest scientific society. The test doesn't screen people, it seeks out evidence of illicit drug abuse in drug residues and metabolites excreted in urine and flushed toward municipal sewage treatment plants.

The approach could provide a fast, reliable and inexpensive way to track trends in drug use at the local, regional or state levels while preserving the anonymity of individuals, says lead researcher Jennifer Field, Ph.D., an environmental chemist at Oregon State University who works with colleagues at Oregon State University and at the University of Washington.

Past estimates of illicit drug abuse in a community were based largely on surveys in which children and adults were asked about their use of illegal drugs. Researchers knew that some were untruthful, with individuals reluctant to admit breaking the law.

Preliminary tests conducted in 10 U.S. cities show the method can simultaneously quantify methamphetamine and metabolites of cocaine and marijuana and legal drugs such as methadone, oxycodone, and ephedrine, according to Aurea Chiaia, a graduate student who is working to refine the process and described details at the ACS meeting.

"Because our method can provide data in real time, we anticipate it might be used to help law officials undertaking surveillance to make intervention or prevention decisions or to decide where to allocate resources," Chiaia says.

Recently, scientists have sought ways to gauge illegal drug use by measuring the levels of drugs and their by-products found in rivers and wastewater. Last year, Italian scientists found ways to detect metabolites for cocaine in the Po River, giving law enforcement officials more accurate estimates on cocaine use in the area. The U.S. Office of National Drug Control Policy has obtained samples from a dozen different waterways in an effort to assess illegal drug use, as well.

Field says the new screening method under development in her lab improves upon the utility of the laboratory tools currently used to identify traces and metabolites of drugs in such studies. Tandem mass spectrometry, for example, is a laboratory method routinely used to identify the unique by-products of various drugs by determining their molecular weight. The problem is, the method frequently requires a time-consuming off-line process to concentrate the samples.

Field and her colleagues have eliminated that step. "By streamlining this process, we can cut back on the use of solvents and bring about a savings in time, therefore saving money," Field says.

Her lab is now refining the technique to verify its accuracy for extremely low concentrations, on the order of a few nanograms (billionths of a gram) per liter. Calculations of drug use based solely on byproducts found in water supplies, especially at low levels, can be subject to error, Field says. To address this issue, her lab is working to identify common indicators, or biomarkers, such as caffeine or nicotine that can be used to sharpen their calculations.

"A lot of things contribute to the flow in wastewater, including agricultural and industrial processes," Field says. "By linking our illicit drug measurements to biomarkers related to measurable human activities, we could compensate for differences in flows that aren't related to human excretion."

The method would eliminate the need to rely on surveys, medical records and crime reports to assess the scope of a community's drug abuse problem, she says, and allow drug enforcement officials to monitor drug use through time and across geographic regions.

"If you're looking for trends over time or space, this will be a suitable methodology," she says. "By using rapid screening methods on a regular basis, we could follow regional (spatial) trends over time in drug use," she says.

American Chemical Society