TORONTO -- As Canada gears up for the legalization of recreational pot on Wednesday, health providers are warning parents and other adults about the potential dangers to children of exposure through second-hand smoke or the ingestion of cannabis-laced edibles.
Even the tail end of a joint can pose a risk if a curious child were to eat it, said Dr. Margaret Thompson, medical director of the Ontario, Manitoba and Nunavut Poison Centres.
"Kids get into everything," she said, noting that with the approach of legalization, poison control centres across the country have already been seeing a big uptick in calls about children who have inadvertently ingested marijuana-infused foods like cookies, brownies and gummy bears.
A study by the Ontario, Manitoba and Nunavut poison centres shows that from 2013 to 2017, annual calls concerning cannabis exposure to children under age 18 rose by 50 per cent, to 234 from 116.
"For the most part, it's edibles we're getting increasing calls about," said Thompson, an emergency medicine specialist and toxicologist in Toronto. "And my biggest concern is that in Canada these are not yet legalized and so there is nothing that makes these products uniform."
Commercially produced cannabis edibles won't be legal in Canada until late 2019, but they are readily available for purchase on the internet and in some illegally operating pot shops. As of Wednesday, Canadians also will be able to produce home-made edibles, as long as organic solvents aren't used in their preparation.
"And we won't have any idea how much cannabinoid or cannabis is in any particular bite or whole brownie or full brownie pan," Thompson said, calling children "completely naive to these products" and at risk for a more intense reaction to the psychoactive component of marijuana compared to adults.
As yet, there is no legislation in Canada requiring edibles to be in child-resistant containers or to carry warning labels, she added.
"So you might have 100 gummy bears that have some quantity of marijuana, oil or extract in them -- and is that eight mg of cannabis or is it 25 mg in each gummy, because often they're not labelled as to how much is actually in them.
"It's meant that you take one, but what child wouldn't eat a whole package of gummy bears?"
Kids who have inadvertently ingested cannabis can experience a number of adverse effects, including being disoriented, agitated and off-balance.
"So they may be falling about the house, they may seem to regress in terms of their (developmental) milestones," she said. "If they were originally walking around, now they're crawling because they can't stand straight."
Seizures and coma have been known to occur in kids who have taken in high concentrations of cannabis, and in rare circumstances children have experienced strokes or heart attacks.
"I think our biggest message is be aware, be careful," said Thompson. "Place your products in a locked box after you've used and out of sight from children."
But edibles don't pose the only potential pot-related risk to children.
Second-hand smoke or vapour from puffing on a joint or bong can also expose kids to the mind-altering component of weed, known as THC or tetrahydrocannabinol, one of more than 100 active ingredients in the budding plant.
"What we know about cannabis smoke is that it is not unlike tobacco smoke, to the extent that if a person is exposed to it they do ingest some of the cannabis constituents," said Dr. James MacKillop, co-director of McMaster University's Centre for Medicinal Cannabis Research.
"So if a child is around parents or other adults who are smoking cannabis heavily, that exposure alone could lead to a meaningful level of cannabis ingestion and in turn psychoactive effects.
"This is particularly problematical in situations where there is low ventilation," such as in an enclosed room in a home, he said from Hamilton.
While getting lungfuls of second-hand pot smoke or vapour wouldn't necessarily make a child feel "high," it could make them feel dizzy and sick, said MacKillop, adding that the adverse effects would depend on how much they breathed in. Those effects could last for a few hours.
"I would absolutely recommend that parents avoid exposing their children to cannabis second-hand smoke of any kind, and that also goes for cannabis vapour. Fundamentally, if it's in the air and there's fairly regular exposure to it, they're likely to ingest it."
MacKillop also endorses Health Canada's admonition that pregnant and nursing women avoid using marijuana, since THC -- which is stored in fat tissue and over time leeches into the bloodstream -- can cross the placenta into the fetus and also make its way into breast milk.
The Canadian Paediatric Society is so concerned about the potential fallout from recreational cannabis legalization on children and youth that its surveillance program plans to track how many young people end up seeking medical attention for serious or life-threatening events related to the use of pot.
The two-year study will run until October 2020 and will include cases from the beginning of September 2018.
