OLYMPIA, Wash. (AP) — A federally funded study confirmed marijuana use went up in Washington after its first legal pot stores opened in 2014.
Marijuana 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.
The research entailed getting sewage from two treatment plants that serve the 200,000 people of Tacoma.
Their findings: consumption of THC doubled from December 2013 to December 2016.
The researchers say they can’t tell whether the increase means more people are using weed or the same old users are consuming more of it.