By Gene Johnson, Associated Press
(AP) — The proof is in the… pee.
A federally funded study has confirmed, not surprisingly, that marijuana use went up in Washington state after its first legal marijuana stores opened in 2014. In fact, consumption appeared to double, at least in one major city, over three years — a conclusion scientists reached by way of the unglamorous work of analyzing raw sewage.
“It’s stinky,” said lead author Dan Burgard, a chemist at the University of Puget Sound. “But we’ve worked with urine, we’ve worked with wastewater, and we’ve worked with port-a-potties. It’s not as bad a port-a-potties.”
The research entailed driving to two sewage treatment plants that serve the 200,000 people of Tacoma, a city whose drug-use trends tend to mirror those of Seattle. The scientists would pick up a cooler full of frozen wastewater samples, thaw them and analyze them using liquid chromatography and mass spectrometry.
They were looking for THC-COOH, a substance produced when the body metabolizes THC, the main ingredient in marijuana that gets you high. THC-COOH is excreted mostly in people’s urine.
Their findings: Consumption of THC doubled from December 2013 to December 2016.
The researchers said they can’t tell whether the increase in metabolites means more people are using weed or the same old users are consuming more of it. Another possible explanation is that the marijuana, edible treats and extracts sold legally in stores are more potent than what was commonly available on the black market.
The findings are in line with other, less disgusting indicators: Washington’s retail cannabis sales amount to more than $1.3 billion a year. And a 2016 state Health Department survey found that 14 percent of adults over 21 reported using marijuana in the previous month, up from 11 percent before voters decided to legalize weed in 2012.
Wastewater sampling has been used for years in Europe and Australia to examine drug usage trends but is fairly unusual in the U.S. The National Institute on Drug Abuse provided $120,000 for the three-year study.
Scott Takushi Pioneer Press via AP