Gee whiz: Testing of sewage confirms rise in marijuana use

SEATTLE (AP) — The proof is in the pee.

A new federally funded study has confirmed, not surprisingly, that marijuana use went up in Washington state after its first legal pot stores opened in 2014. In fact, consumption doubled over three years — a conclusion scientists reached after performing the decidedly unglamorous work of analyzing raw sewage.

The researchers tested wastewater for a substance that is produced when people metabolize the active ingredient in pot. It is excreted in urine.