Spokane pot use measurable by THC levels in wastewater, panel told

The most important numbers to Spokane city officials looking for accurate data about residents’ marijuana use may be one and two.

“Nobody can lie about what’s showing up in the sewage,” said American Civil Liberties Union attorney Alison Holcomb to Spokane City Council’s Marijuana Policy Subcommittee on Tuesday when suggesting that the city test its wastewater to find out how much pot is being used.

Representatives of schools, law enforcement agencies, nonprofits and local government met to discuss what information needs to be collected as recreational marijuana enters its fourth month of legal sales and policymakers look to maximize revenue while ensuring public safety.

A list of figures that community members said they need to collect includes pot sales, developments in the tourism industry and trends of use among minors. Testing sewage, which can be frozen for later inspection, would provide only general use figures, not broken down by age, said Holcomb, the architect of Initiative 502, which legalized recreational use of marijuana.

But Councilman Jon Snyder showed support for the idea of testing wastewater.

“What an awesome new use for our sewage,” he said, to laughter from assembled stakeholders.

Holcomb said measuring levels of THC – the psychoactive element in marijuana – present in sewage provides a more accurate level of trends than self-reporting on surveys, which can be swayed by attitudes and fears of consequences. Researchers in the state already have developed testing methods, she said, citing reports published by researchers at the University of Washington and the University of Puget Sound targeting college students.

Daniel Burgard, a University of Puget Sound chemistry professor, has previously published studies examining traces of amphetamines in sewage collected at colleges during times of high stress, such as final exam weeks. He is collecting samples from multiple sources across Washington to establish trends in marijuana use following the onset of recreational sales earlier this summer, according to news reports.

Burgard, working with other University of Puget Sound researchers, found a significant difference between self-reporting of stimulant use by college students and the measured amounts in campus sewage in an article published in May in the journal Addictive Behaviors. The relatively new field of drug testing sewage has spawned a cottage industry of ethicists who debate the legality of what amounts to a mass drug test. A paper published in the journal Addiction, often cited by the community as an ethical basis for conducting wastewater analysis, explored many of the major concerns, including invasion of privacy and fears of legal consequences or stigmatization. The authors concluded the potential benefits outweighed the harm.

The analysis “has considerable potential to serve the public good,” the authors wrote. They cited the unlikelihood law enforcement would pay the steep fees needed for testing in order to prove drug cases and the inability of current technology to determine the single source of illicit drugs.

Spokane wastewater director Dale Arnold said the city’s sewage hasn’t ever been tested for THC.

Arnold said he would check with a lab this week to find out how possible it is to get readings for THC from wastewater. But he suspects it might be difficult.

“A large portion of that wastewater doesn’t come out of human beings,” he said.