It's been nearly one year since cannabis was legalized in Canada and a professor at the University of Northern British Columbia says knowing who is using it is important to develop sound policy aimed at reducing cannabis-related harms.

Russ Callaghan, medical professor at UNBC, is the lead author of an article in the forthcoming December issue of the Journal of Drug and Alcohol Dependence that identifies who consumes the most cannabis in Canada.

Callaghan and a team of researchers looked at data from the federal government's 2018 National Cannabis Survey to find out who are the biggest users and how that should inform public policy.

According the survey conducted prior to legalization — which did not distinguish between legal and illegal cannabis — 10 per cent of people use roughly 66 per cent of the cannabis in Canada. The data also showed  males reported higher use than females and males aged 15-34 were the highest using subgroup.

Callaghan said the usage rates are similar to alcohol statistics which show the heaviest users consume a high proportion of alcohol in Canada.​

'A large societal experiment'

Possible harms from cannabis use include impaired driving, lung cancer and personal injury, although he noted there is not a lot of evidence yet linking weed to non-traffic related injuries.

"We've legalized it so it's a real large societal experiment," said Callaghan in a phone interview on CBC's The Early Edition, adding particular risks associated with edible cannabis products may become evident after they become legal this year. 

With weed, as with alcohol, consumption rates can be influenced by prices and taxation, the availability of stores in a neighbourhood and their operating hours.

The study included a team of researchers from UNBC, the University of British Columbia, the Centre for Addiction and Mental Health (CAMH), and the Canadian Institute for Substance Use Research at the University of Victoria.