Positive shifts since cannabis legalization, but more health data still needed, says researcher

Three years after recreational cannabis was legalized in Canada, a researcher says the change spawned "partial successes" — but information on marijuana's impact on health is still needed.

"Data's still out on the final conclusions about this large social experiment," said Jason Busse, associate director of the Michael G. DeGroote Centre for Medicinal Cannabis Research at McMaster University in Hamilton.

The federal government legalized recreational marijuana in October 2018, opening the door to a lucrative market for the regulation and sale of cannabis while reducing the impact of black market sales.

Busse says that while trends indicate positive shifts away from the illicit market, there is little data to indicate whether legalization has had any effect on the health of Canadians.

He spoke with Cross Country Checkup host Ian Hanomansing about what data is needed. Here is part of that conversation. 

Has the government achieved, do you think, what it set out to do with legalization?

There are partial successes and the jury's still out as we collect more information. The issue was there was a large proportion of Canadians that were using cannabis recreationally before it was legal to do so. Somewhere between 15 and 20 per cent of the population was endorsing use of cannabis in the last year. 

The idea of making it legal was to pull a lot of those funds from the black market to turn them into a proper source of revenue [and] to standardize and regulate a product to provide it in a safer fashion, in order to make this another controlled substance that was available to individuals that might have an interest, as you would the same for alcohol or tobacco. 

So there has been some migration from the illicit market. There's still about 50 per cent of Canadians that use cannabis that will endorse acquiring it at least some of the time from illicit sources.

In terms of whether or not we're seeing an uptick in some of the concerns around health issues, we're not quite sure. There has not been a lot of information to suggest we're seeing a large increase in motor vehicle accidents, a large increase in early-onset psychosis in adolescents and emerging adults.

There have been some signs there's an increase in some emergency department visit numbers for things like cannabis hyperemesis syndrome, which occurs when you take on too much THC at one time. 

Let's talk about that 50 per cent number — that 50 percent of cannabis purchases seem to happen in the store, which obviously means the other 50 per cent is happening on the black market. Why are so many people still refusing to — or reluctant to — buy it from the regulated system?

It takes some time for people to shift their purchasing to a new source. So you are seeing changes, even from 2019 to 2020. The respondents to the National Cannabis Survey suggests that there is increased migration to that legal market.

But as you noted, there's still a large proportion that haven't. Some will talk about issues of price. Some will talk about issues of quality, and you heard that from one of the prior callers. 

There is less variability in products available through legal channels. The edibles only became available as of 2019 — it was given a year to just sort of bring those in. 

So I think as time goes on, we'll see increased migration to the legal market. You're still going to see some holdouts as long as the illegal market can provide greater variety and in some cases, lower price points to acquire these same products.

From a public health perspective, what concerns you most as we're three years in here to Canada's approach to legalization?

We want to see that the net benefits exceed the net harms for making this product widely available to Canadians. 

The federal government has downloaded a lot of the responsibility onto the individual provinces and territories, and so you see some variability in the age of allowable use.

Some of the concerns around setting this sort of age limit came from a position paper that was published by the Canadian Psychiatric Association in 2017, and they acknowledge the potential for cannabis use to be associated with neurocognitive issues and, again, early-onset psychosis. So they were pushing for a minimum age of 21. And of course, that was not completely adopted for the simple reason that the largest proportion of individuals using cannabis are in those younger age ranges.

As we sort of try to reconcile bringing the largest population ... that are currently using [into the legal market], we have to wonder if there could be some potential consequences to that.

So we have to keep collecting the data — and I think the government's doing a good job of that in many cases — monitoring these emergency department visits, looking to see if there is increase in motor vehicle accidents or other areas where you would imagine taking on recreational psychotropic products might have an effect. 

Written by Jason Vermes. Produced by Abby Plener. This Q&A was edited for length and clarity.