Cannabis plants in BlissCo, a manufacturing facility in Langley, B.C. (Ashley Wadhwani/Black Press Media)

Here’s a first look at Canada’s sewage tests for cannabis use

The first-of-its-kind tests involve gauging traces of THC, the active ingredient in marijuana, at 15 wastewater treatment plants in Canada

Canadians eat or smoke anywhere between 400 to 1,600 tonnes of cannabis per year, according to a few months of sewage samples examined for the federal government.

The wide-ranging estimate, released by Statistics Canada on Thursday, is the first look at cannabis use through a new technique called wastewater-based epidemiology. The tests involve gauging traces of THC, the active ingredient in marijuana, at 15 wastewater treatment plants in five different cities, including Vancouver.

After cannabis is metabolized in the body, traces of THC are left behind in human waste. Scientists collected wastewater on the second week of each month from March to August this year – before cannabis was legalized in Canada on Oct. 17.

As expected, more cannabis is consumed in Canada’s larger cities. Montreal had the highest rate of consumption at roughly 1,922 grams per week, according to the analysis. Toronto had the second highest at 1,257 grams, followed by Vancouver with 721 grams.

READ MORE: Canadian trial to compare cannabis and fentanyl in relieving chronic pain

READ MORE: B.C. woman looks to reduce stigma surrounding weed-smoking moms

The sample tests were meant to overcome under-reporting by cannabis users, often caused by the stigma of the drug and reluctance for people to admit their illegal purchases.

“One consequence of under-reporting is that the size of the black market for cannabis will be similarly underestimated,” the report reads.

“As a result, without a direct measurement of cannabis consumption, the reduction of the black market for cannabis – one of the objectives of the legalization of non-medical cannabis – will be hard to track.”

READ MORE: 10 things still illegal in the new age of recreational cannabis

While the estimates offer a first look at the truth behind cannabis use, Statistics Canada said the numbers are experimental and that more information is needed, such as how much of the drug is excreted, its potency and the way the drug is consumed. Other factors to consider include different chemicals in the various treatment plants themselves.

“In the case of cannabis, there are many different kinds of products, with different THC potency levels, and this adds further complexity to estimation methods,” the report reads.

Sampling will continue until the spring of 2019.

WATCH: Inside a B.C.-based marijuana production facility


@ashwadhwani
ashley.wadhwani@bpdigital.ca

Like us on Facebook and follow us on Twitter.

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

B.C. firefighters only responding to most life-threatening calls during COVID-19 pandemic

The directive comes after province spoke with paramedics, fire services, according to top doctor

‘An extra $220 every 90 days’: B.C. patients pay more dispensing fees due to prescription limits

Kelowna woman says it’s outrageous to charge for refills every 30 days

West Coast restaurateurs feeding the front-line

“My community was my main focus out of the gate.”

‘Better days will return’: Queen Elizabeth delivers message amid COVID-19 pandemic

The Queen said crisis reminds her of her first address during World War II in 1940

Emergency aid portal opens Monday, cash could be in bank accounts by end of week: Trudeau

Emergency benefit will provide $2,000 a month for those who have lost their income due to COVID-19

Education, not enforcement: B.C. bylaw officers keeping a watch on physical distancing

A kind word, it turns out, has usually been all people need to hear

COVID-19: Hospitals remain safe for childbirth, say Vancouver Island care providers

North Island Hospital has been asked to share its perinatal COVID-19 response plan

Canadian cadets to mark 103rd anniversary of Vimy Ridge April 9 virtually

Idea of Captain Billie Sheridan in Williams Lake, B.C. who wondered what to do in times of COVID-19

B.C. VIEWS: Pandemic shows need for adequate care home staffing

Seniors in B.C. care homes face challenging times

QUIZ: How much do you know about hockey?

Take this test and find out how well you know Canada’s most popular winter sport

Researchers look at humidity as a weapon in the fight against airborne viruses

Regular hand washing, physical distancing and PPE for health care workers remains best line of defense

Most Read