Sewage test: Will you smoke pot now that it's legal?

Sewage test: Will you smoke pot now that it's legal? »Play Video
A researcher tests drug levels at a Seattle area sewer. (Photo: Ross Mulhausen, University of Puget Sound)

SEATTLE - If you didn't smoke marijuana when it was illegal, will you smoke it now that it's legal?

No one really knows how much marijuana use in Washington State will change. But one local researcher has already launched a study to find out, using a method becoming more common: measuring drugs in sewage, often called wastewater.

"I have just THC metabolite in this test tube," said a graduate student researcher in a lab at the University of Puget Sound in Tacoma. They are testing samples collected months ago from undisclosed sewage treatment plants in Washington State to determine the level of marijuana use before it became legal to buy. They'll take comparative samples again after retail stores are fully up and running. Results will show a trend, not so much an estimate of average use per person.

Testing wastewater is more accurate than other measurements. When it comes to surveys, drug users don't always tell the truth, experts conclude.

"And so the wastewater should be a more objective way of looking at consumption," said Dan Burgard, the UPS researcher heading up the study of changing marijuana usage. He agrees pot smokers can lie to people conducting surveys. But it's "pretty tough" to lie to the toilet.

Authorities in many other states are watching to see whether legalization increases pot use and, if so, by how much.

"Nobody really knows that," said Burgard. "People call Washington and Colorado the test states. And so we want to figure that out."

Burgard and team made headlines recently by testing the wastewater coming out of part of the UPS campus for levels of Adderall and Ritalin - the so-called smart drugs. He found use skyrocketed during mid-terms and finals week. "And with one finals period being almost 8 times as higher."

Burgard called this vital public health data. "That's the thing. It's all sort of so, so new. You can just measure whatever."

How about measuring drug use and types of drugs from a music festival, a sports event, a school, commercial truckers on the road, or entire towns? Such uses have been called a urinalysis for an entire population, without consent.

Researchers are using this emerging technology to measure trends in drug use among hundreds or thousands of people - at the population level, not individuals or individual homes. But top experts say that is possible, raising all kinds of ethical, moral, legal and privacy issues.

"Here's the reason I am not worried about it," said Caleb Banta-Green emphatically. He's one of the top drug abuse researchers in the U.S. and is the senior scientist at the University of Washington's Alcohol and Drug Abuse Institute. "Anybody with a good chemist in any level of government can already do this. If law enforcement wanted to do this and had the proper domain to do that, they could do it. I can't stop them from doing it. What I can do as a scientist is say 'here's what I'm doing.' I think the thing that's important is the population level in order to inform good health responses."

Burgard agrees but said certain levels of drug use for a population, such as schools or even prisons, might have ramifications for people in that group who did not use drugs. "If there were serious consequences that came from that, people who were not abusing drugs were adversely affected by that, that could certainly be a problem," he said. "So, I think it's just using the data responsibly. But certainly there's that issue."

Banta-Green has already detected drug use in prison, even though it is less than in general society. He said he's currently writing a peer-reviewed paper on the results which, he adds, could potentially prompt tighter security and drug programs behind bars.

In 2008, Banta-Green tested samples from 96 Oregon communities revealed meth use in every one of them, cocaine use in 80% -- especially cities -- and ecstasy use in half of them but much higher in cities: Giving each town a snapshot of its particular drug problem.

"There was a lot of drug use across the state which says to me 'we gotta work on this.' It's not - people can't get away with saying 'it's not our problem, it's not here'," said Banta-Green. "It's irrefutable. And that's really important when it comes to this, I think."

Burgard reaches into a large freezer in his UPS lab, shuffles through black plastic bags and pulls out a vial. "This is murky wastewater in the form that it comes to the treatment plant." He said it can lead to significant and beneficial public health policies.

Banta-Green said testing wastewater can show which drug policies are wasting money and which are working, and possibly mean spending less money on police, courts and jails.

And it all starts with a flush of the toilet.