Canada intends to track consumption by monitoring what Canadians flush down the toilet.
Statistics Canada's main goal is to get an unbiased read of how legalization affects cannabis use. “There are things like surveys and what not where people report frequency of use, but the consumption numbers weren't quite as reliable as we would like them to be,” Peluso told NPR.
In addition to gathering consumption data, Peluso explained, it might be possible to subtract legal weed sales and figure out how much cannabis is being sold illegally.
How is such a calculation reached? A great question, which NPR says gets “really murky really fast.” Pun intended?
Peluso says Statistics Canada will consider some basic questions that get quite complex on a national scale, such as are suburban tokers peeing in the city but consuming in the suburbs?
While researchers say detecting THC in diluted wastewater is "relatively straightforward,” using that number to determine exactly how much cannabis is being consumed is a whole different ballgame.
It comes down to something Burgard calls the consumption-excretion relationship, which depends on a number of different factors, including whether the cannabis is ingested, smoked, or vaped.
Tolerance and other biological and metabolic differences among individuals also make determining the exact amount of cannabis being consumed in a given population a challenging number to land on.
While the main goal of Statistics Canada is to determine how much weed Canadians are consuming by measuring THC in their sewage, Peluso also hopes to be able to determine the amount of cannabis being sold illegally.
Good luck with that.