Emergency room visits for severe car accidents involving marijuana saw “large increases” over time in Ontario and rose more steeply after Canada legalized recreational cannabis, a new study has found.
In 2018, Canada became the second country to approve cannabis for nonmedical purposes, following Uruguay’s decision to do so in December 2013.
Five Ottawa medical researchers published the study Wednesday in JAMA Network Open.
They analyzed 947,604 emergency department visits for traffic injuries in Canada’s most populated province over three periods: pre-legalization (January 2010 to September 2018), legalization with restrictions (October 2018 to March 2020) and commercial expansion into retail stores (April 2020 to December 2021).
Researchers found that marijuana-related visits to the ER for traffic injuries jumped by 94% from before legalization to the period of restricted legalization.
The final period in which the government okayed an expansion of marijuana stores and products, which overlapped with the COVID-19 pandemic, saw an even greater increase of 223% from before legalization.
“Our findings caution that the cannabis involvement in traffic injuries may have begun accelerating after Ontario switched from a heavily restricted legal market to a more commercially oriented market with enormous store and product expansion,” Dr. Daniel Myran, a co-author of the study and professor of medicine at the University of Ottawa, told The Washington Times.
“Placing restrictions on cannabis marketing and promotion along with retail store availability may be important measures to reduce cannabis-impaired driving in regions with legal cannabis,” he added.
Researchers found the rate of traffic injury ER visits involving cannabis increased by 475.3% over the entire period, growing from 0.18 for every 1,000 visits in 2010 to 1.01 per 1,000 in 2021. At the same time, the rate of traffic injury visits involving alcohol ticked up by 9.4%, from 8.03 per 1,000 visits in 2010 to 8.79 in 2021.
That comparison suggests marijuana legalization “may have played an important role” as recreational use and related traffic injuries snowballed for more than a decade, they noted.
“Legalization of nonmedical cannabis with widespread retail access and increased cannabis product variety may have further increased these visits despite laws specifically aimed at deterring cannabis-impaired driving,” the researchers wrote.
In Ontario, it is illegal for people aged 16 to 21 years to drive with detectable levels of tetrahydrocannabinol (THC) or alcohol in their system. THC is the psychoactive substance in cannabis that — in the higher doses typical in newer forms of marijuana — can produce intense nausea, hallucinations and scream-vomiting in users.
Despite the law, the study found that 26.1% of cannabis-related traffic injuries involved people aged 16 to 21, compared with 12.1% of alcohol-involved traffic injuries.
“Younger adults and males appear to be at particularly increased risk of cannabis-involved traffic injuries,” the researchers noted. There is a potential need for greater interventions, including education on cannabis-impaired driving, enforcement activities, and policies to regulate access to commercial retail markets.”
According to the study, nearly 8 in 10 of the 426 emergency visits for marijuana-related automobile injuries involved men. Patients were more likely than not to be under 30, have histories of alcohol or substance abuse and come from lower-income neighborhoods.
The most common reasons listed for the visits were “harmful cannabis use” (41.1%), “acute intoxication” (33.1%) and “cannabis dependence or withdrawal” (9.6%).
Additionally, 41.8% of the marijuana-related car accident visits to the ER also involved alcohol.
On average, the study reported that marijuana-related car injury visits were “more severe” than those not involving the drug. That resulted in “higher rates of hospital and ICU admission,” and higher rates of patients arriving by ambulance.