Legalization of Edibles Linked to Increased Cannabis Poisonings Among Seniors: Study

A variety of cannabis edibles are displayed at the Ontario Cannabis Store in Toronto on Jan. 3, 2020. The Canadian Press/Tijana Martin

The legalization of edible cannabis products in Canada is being linked to a rise in cannabis poisoning among older adults, according to recently released research.

Emergency department visits for cannabis poisoning among adults aged 65 and over have increased substantially in Ontario since edibles—such as baked goods, candy, and beverages—became legally available in January 2020, a study published May 20 in the peer-reviewed medical journal JAMA Internal Medicine has found.

The stats from 2020 to 2022 were nearly four times greater than those from 2015 to September 2018, just before pot was legalized, and nearly 1.5 times greater than the period from October 2018 to December 2019, when only dried cannabis flowers were legally available for retail sale, says the report co-authored by three Toronto University physicians and scientists.

Lead author Dr. Nathan Stall, a geriatric specialist at Sinai Health in Toronto, says cannabis poisoning is completely different from being “high.”

“These are not people getting too high, being giddy and laughing,” Dr. Stall said.

“These are people very sick to the point where health-care practitioners, without knowing that they’ve consumed cannabis, consider other serious health conditions, like stroke, serious infection, [and] serious metabolic abnormalities.”

Older adults are at “particularly high risk of adverse effects from cannabis” due to age-related physical changes, increased use of medications, and the likelihood of seniors suffering from more than one health issue, says the study written by Dr. Stall, clinical pharmacologist and toxicologist Jonathan Zipursky, and founding director of the Women’s Age Lab Paula Rochon.

Trends

The study examined three periods during an eight-year span, using Ontario Ministry of Health administrative data to examine ER visits by older adults.

The first period spanned pre-legalization from January 2015 to September 2018. The second period spanned from October 2018 to December 2019, during which legalization permitted the sale of dried cannabis flowers only. The third period spanned from January 2020 to December 2022, during which legalization also permitted the retail sale of edible cannabis.

The study reported that the pre-legalization rate of emergency room visits among older adults was 5.8 per 100,000, but that climbed to 15.4 per 100,000 during the first phase of legalization. The rate jumped again when edibles were legalized, this time to 21.1 per 100,000 visits.

The data may underestimate the true magnitude of cannabis poisonings among seniors because it is limited to ER visits and doesn’t track those who may have obtained care elsewhere or not at all.

“Older adults may have sought care elsewhere or not at all, especially since the legalization of edible cannabis immediately preceded the COVID-19 pandemic,” the study said.

Cannabis Poisoning

Cannabis poisoning isn’t typically fatal, but it can be quite unpleasant and comes with side effects such as chest pain, rapid heartbeat, nausea and vomiting, psychotic episodes, respiratory depression and severe anxiety, according to Health Canada.

Seniors are also especially at risk of confusion due to higher incidences of both cognitive impairment and use of medications such as sleeping pills and sedatives, which can affect mental processes, the study found.

Cannabis poisoning is just as likely to occur among seniors who have previously used marijuana as it is in those who have not, because edibles have a delayed peak effect of roughly three hours. Those accustomed to the quick high offered by smoking pot may ingest “excessive doses” of edibles before “peak effects” manifest, the report said. This is known as dose-stacking.

Accidental ingestion is also common because edibles are rarely discernible from typical food sources. Other causes of cannabis poisoning pointed out in the report are ease of access, lack of age-specific dosing instructions, and absence of safe and effective treatment options for chronic pain, sleep disturbances, and dementia.

Cannabis Use in Seniors

While cannabis use is less common among seniors than in other age groups, it has accelerated at a much quicker rate among those 65 and older.

Roughly 40,000 seniors reported using cannabis in 2012, a sharp contrast from 2019 when more than 400,000 seniors said they had used cannabis in the past three months, according to Statistics Canada figures.

The data showed that more than one-quarter of seniors who used cannabis were new users. The most common reason listed for cannabis use among seniors aged 65 and older was medical, at 52 percent. The remaining seniors were evenly split with 24 percent each listing non-medical reasons only and both medical and non-medical reasons, StatCan said.

Regulated edibles, under Canadian law, must be sold in individual packaging containing no more than 10 mg of tetrahydrocannabinol (THC). Unregulated edibles can contain much larger amounts of THC, according to the Canadian Medical Association Journal (CMAJ). An “intoxicating dose” of edibles contains 10 mg to 30 mg of THC.

“The impracticalities of dividing edibles into smaller portions is a common reason for overdose,” the CMAJ said. For example, it can be difficult to determine what one-tenth of a 100 mg THC cookie looks like.

The study recommends the government implement “measures to mitigate unintentional exposure” in seniors and publish age-specific dosing guidance.

The Canadian Press contributed to this report.