Field said there were a few surprises in what she and Banta-Green found in the water the first time they used their new process to test a local community. "What surprises me could simply be a function of my naivete," Field said. "For example, there are enough users excreting enough drugs that it's measurable."
She also was surprised to get queries about the confidentiality of the test: There's no way to pinpoint who is using drugs and who isn't because the sewer is a public commons. Everybody uses it. Field said the drugs found in the water were the "usual suspects," including cocaine, LSD, heroin and meth.
The new test method could be used to track drug excretion rates over time to spot trends that may be applied to drug intervention policies, Field said. "I see a lot of interest in individual communities to simply know if they have a drug issue that you can see in their [wastewater]."
The method could be used as an early warning system for the presence of drug problems within a community, according to Banta-Green. There's typically a lag of five to 10 years between the time an individual starts using drugs and the time he or she gets treatment. Mortality is obviously another indicator with a long lag time. "With this [wastewater test], theoretically, there's not a lag," said Banta-Green. "We're talking about a 24-hour lag, not a five-to-10-year lag."
The new test could give law enforcement a head start on addressing drug problems, enabling agencies to allocate resources before problems get out of hand, Banta-Green said. "This would give law enforcement the data to go to captains or chiefs and say, 'Not only do we think we're seeing drugs, we're hearing about it and it's in the water.'"
The test, however, cannot tell exactly how many people are using drugs and who they are, Banta-Green said. "We're really talking about a community load of a drug, and not how many people it is."
But there is some correlation between the load and heavy use by a community. If the test indicates a large load of meth in the wastewater, that's a good indicator of substantial use. "It's crude in terms of trying to quantify the number of people," Banta-Green said.
The utility of the test is being able to track drug-use changes over time and how it moves within a region, he said. "If it's getting done throughout the state, you can know geographically where it is, and if it's spreading."