Marijuana legalization linked to increased cannabis poisoning of seniors

Research published on Monday indicated that since Canada legalized marijuana and specifically legalized edibles, emergency room visits by older people for cannabis poisoning have increased.

What were the parameters of the study? The research, published by the JAMA Network, examined data provided by the Ontario Ministry of Health to track cannabis poisoning incidents involving older people in emergency departments over eight years. The eight-year window started in 2015, three years before Canada legalized marijuana, and ran through the end of 2022. Canada legalized the use and sale of edibles in late 2019.

What sort of findings did the research yield? Researchers found that cannabis poisonings in older people increased significantly during the first 14 months of legalization, when marijuana, but not edibles, was legal. During the next two years—after Canada legalized edibles—cannabis poisonings increased even more.

Was this trend only seen in older people? The National Library of Medicine reported last year that between 2015 and 2021, the number of children heading to the hospital for cannabis poisonings also increased and that almost half of those situations also involved edibles.

What’s the difference between edibles and other methods of using marijuana? Edibles are food products that include cannabis ingredients. Smoking marijuana transfers the THC—the chemical that gives users a “high”—straight to the user's lungs and, from there, to the bloodstream, according to the Canadian Centre on Substance Abuse and Addiction.

Munching on edibles, however, sends the THC to the user’s stomach, then to his or her liver, and then finally to the bloodstream. That lengthens the time between ingesting the drug and feeling its effects, pushes back the time when the consumer will feel the peak high, and lengthens the duration that they will feel that high.

The U.S. government website Just Think Twice characterizes consuming edibles as more dangerous than smoking marijuana. It says the chance for overdose is much higher with edibles since users might consume more because they don’t feel the effects immediately. It also notes that the levels of THC in edibles are very hard to measure. Additionally, if users have other medications in their system when they consume an edible, their body could metabolize THC differently and flood their system with five times as much THC as it would otherwise.

Dig deeper: Listen to Mary Muncy’s report on The World and Everything in It podcast about medical experts’ opposition to legalizing marijuana.