Canada’s wastewater reveals drug use

Oct 4, 2019

According to the results of a new pilot study Canadians’ drug habits significantly vary from coast to coast. The study examined wastewater from five Canadian cities for the presence of cannabis and other illegal substances such as methamphetamine and cocaine. The results revealed that out of the five cities reviewed the highest consumption of cannabis occurs in Halifax while the highest use of methamphetamine takes place in Edmonton.

The 12-month study carried out by Statistics Canada is part of the larger initiative to measure total societal use of cannabis and misused drugs and determine the social and economic impact related to legalization of cannabis. The study’s principal investigator, Tim Werschler, told CBC News that the obtained results also assist the federal government in estimating how much cannabis is being bought on the black market following its legalization in October 2018.

As part of the study, wastewater samples were collected from sewage treatment plants in Halifax, Montreal, Toronto, Edmonton and Vancouver beginning in March 2018 until February 2019. The analysis of the data obtained showed that cannabis consumption across the country is varied, with Halifax residents identified as top cannabis consumers, followed by Montreal and then Toronto residents.

The study also revealed that cannabis use was lower in Vancouver and Edmonton, but more traces of methamphetamine were found in their wastewater compared to cities in eastern Canada. Interestingly, methamphetamine metabolites found in Edmonton and Vancouver wastewater samples were almost four times higher than in samples collected in Montreal and Toronto. In contrast, Halifax samples, which scored the highest on cannabis use, also demonstrated lowest methamphetamine concentrations.  

Moreover, the study examined the samples for presence of the opiate metabolite morphine. The results revealed that samples collected in Edmonton and Vancouver had higher concentrations of morphine than the other three cities examined, which could be revealing heroin or prescription opiate use, according to Werchler. “It is evidence that these [morphine] levels reflect higher illicit use of some compounds,” the researcher said.

Seasonal variations in cocaine use were also revealed, with consumption being higher in the summer, decreasing in the fall and increasing again in the winter. Cannabis use was highest in May, June and December of 2018. However, there were no seasonal variations found in methamphetamine use.