How does cannabis smoke compare to tobacco smoke?

With Edmonton city council considering relaxed rules around cannabis consumption in public, the science is still out on how second-hand cannabis smoke might affect people.

Fiona Clement's research was brought up in council committee discussions around the proposed rules, which would allow people to smoke cannabis outside inpublic places like parks and sidewalks. The new cannabis rules would be similar to current tobacco bylaws.

• City committee recommends allowing smoking of cannabis on sidewalks

There simply isn't enough published research to know how cannabis smoke compares to tobacco smoke, said Fiona Clement, the director of the Health Technology Assessment Unit at the U of C.

"I would not be comfortable with the evidence to say that cannabis smoke is worse for you than tobacco smoke," Clement told CBC's Edmonton AM Monday. "It's not as nuanced as it could be."

There's evidence that shows cannabis affects people differently than tobacco smoke, Clement said. When it comes toTHC levels in second-hand smoke, one study showed people exposed to "intense exposure levels" were feeling high.

But Clement said the study didn't quite replicate a real-life situation, which means it only answers questions in extreme cases.

Three studies have looked at the toxicity of cells in the body and how aspects of cannabis can result in changes to a person's genetic makeup. But Clement said three studies aren't enough.

"We do know that exposure to cannabis smoke is not harm-free," Clement said. "[But] there are lots of unknowns."

There also haven't been any studies looking at the health of people exposed to cannabis for long periods of time. Clement said the lack of studies is likely because of the additional barriers researchers have to overcome to study illegal substances.

Despite the lack of knowledge around how cannabis affects the body, Clement said she supports the more relaxed rules regarding public cannabis consumption.

"It's not that uncommon to see people smoking joints quite freely within a public space already," she said. "If we're not going to enforce bans, I don't see the point in having them."