Edmonton's raw sewage helping Ottawa track cannabis consumption

Federal researchers are peering into the toilets of Edmontonians in an attempt to measure how much the city is smoking up.

Scientists started testing city's raw waste last month

Statistics Canada has hired a contractor to examine the raw sewage of municipalities across Canada as pot legalization nears. (Shutterstock / Ollyy)

Federal researchers are peering into the toilets of Edmontonians in an attempt to measure how much the city is smoking up.

Scientists hired by Statistics Canada will be analyzing sewage samples for traces of THC, the active ingredient in marijuana.

The icky research is part of a national study to determine exactly how much marijuana Canadians are consuming.

Flushing out the truth

"We're hoping to do this sampling on a monthly basis," said Tony Peluso, an assistant director at Statistics Canada.. "We'll have a few months pre-legalization and post-legalization, and for a while after that.

"We're hoping to track the consumption over time and how it's responding to different policies."

The raw sewage samples will help Ottawa determine how much cannabis is coming from the black market, Peluso said. 

It will also provide data on 18 other drugs, including cocaine and opioids.

"If we can come up with an estimate of consumption, then we can also figure out what the local sales are, by subtracting one from the other," Peluso said. "One of the reasons behind the legalization or marijuana was to shrink the size of the black market so we can see how that's changing over time."

'The good people of Edmonton volunteered'

Statistics Canada announced in February it will spend up to $600,000 a year to regularly test 15 to 20 municipalities across the country, but initially declined to name the communities which had signed on.

Peluso said testing in Edmonton began last month after the city volunteered to participate. The data will be made publicly available through regular Statistics Canada publications, he said.

"We were just trying to find out which municipalities might be interested and the good people of Edmonton volunteered to participate."

There are limitations to the measurements, Peluso cautioned. 

Every person metabolizes drugs differently. The research relies on population figures which may be inaccurate, and the estimates may not account for large tourism or commuter populations.

Researchers can only estimate, but the samples will still be more reliable than a public survey, said Peluso.

Some people don't want to divulge that they use drugs, while others may not have an accurate idea of the amount of cannabis they're actually consuming.

"Surveys are good, and surveys in some ways are better than the wastewater, because they tell you about who it is that is consuming the cannabis," he said. "But not everybody responds quite accurately in a survey."