This article originally appeared on VICE Canada.

An emergency room doctor in rural Ontario is getting slammed for a viral tweet in which she claimed weed edibles kill children.

On Friday, Merrilee Brown tweeted, “In ER last night I treated someone for a cannabis induced psychosis from cannabis ‘edibles,’ in this case, a chocolate bar. She ate one piece of the 16 piece bar. That piece had 20g of THC equivalent to 20 joints! Edibles are often so concentrated that they can be fatal in kids.”

The statement has been retweeted more than 10,000 times, but many researchers and cannabis experts challenged Brown’s claims on a number of fronts. For one thing, there is no evidence that cannabis ingestion has ever killed anyone. For another, it doesn’t make sense that a single piece of the chocolate bar, which she said was a total of 225 grams, could contain 20 grams of THC. (THC doses in edibles are generally measured in milligrams.)

Brown did backpedal slightly, admitting “Perhaps I misread the packaging—I am by no means an expert in edibles—but the math doesn’t work out for a 16-piece bar,” but she also doubled down by tweeting case studies in an attempt to stress the risk of weed to children. VICE reached out to experts to fact-check Brown’s claims.

Claim: Cannabis ingestion can induce psychosis

Verdict: Misleading

Rebecca Haines-Saah, a public health policy expert and professor at the University of Calgary, told VICE there’s no evidence to suggest weed directly causes psychosis or illnesses like schizophrenia. There have been studies that have shown links between cannabis use and the early onset of schizophrenia, particularly in people with pre-existing conditions or a family history of mental illness, but those links are far from concrete. Haines-Saah told VICE it’s far more likely the patient Brown treated was simply having a bad trip, including anxiety, paranoia, or hallucinations.

Bonni Goldstein, who has been a pediatrician for 28 years, including 13 as a pediatric emergency room physician, told VICE edible ingestion creates more of a psychoactive effect than just smoking because the THC goes through the liver and creates a metabolite called 11-hydroxy-THC. For this reason, she said cannabis overdoses are most common when people take edibles but even in that case, “you cannot fatally overdose on cannabis,” she said. Symptoms of a cannabis overdose might include paranoia, anxiety, irrationality, feeling like time has stopped, or hallucinations, but she said you can usually talk someone down from those effects. True cannabis psychosis is extremely rare and it’s hard to prove, said Goldstein, who has been a pediatric cannabis specialist for the last ten years.

Claim: One piece of a chocolate bar had 20 grams of THC equivalent to 20 joints

Verdict: False

Simply put, “20 grams would be a ridiculous number,” said Goldstein. “It is much more likely 20 milligrams.” Goldstein told VICE 20 mg of THC could cause a cannabis overdose that would be “uncomfortable” in inexperienced users, especially children or the elderly. For an experienced user, a 20-mg dose wouldn’t be excessive.

Haines-Saah said because the edible was illicit (edibles aren’t legal in Canada), it’s hard to know if it was even labeled properly. However, she said edibles should be regulated and legalized “so we don’t have random products with unknown concentrations.”

Claim: Edibles are often so concentrated that they can be fatal in kids

Verdict: False

Goldstein, who worked in the pediatric ER at Los Angeles County/University of Southern California, told VICE Brown’s claim that cannabis consumption can be fatal in kids is not true. “The [Centers for Disease Control] stopped tracking deaths due to cannabis because there were none year after year,” she said.

She pointed to a case out of Colorado where doctors described an 11-year-old’s death from myocarditis (heart inflammation) as a cannabis-associated death because THC was in his system. But those doctors later admitted they couldn’t prove cannabis was the cause of death. Goldstein said THC and CBD are anti-inflammatories.

“There’s nothing in the literature to support the word ‘fatal’ in this doctor’s tweet,” said Goldstein.

In subsequent tweets, Brown referenced case studies seemingly showing the adverse effects of weed on children, so we fact-checked a couple of those as well.

Claim: There’s an increase in critical care unit admissions for children in US states where cannabis was legalized

Verdict: Yes, but that doesn’t prove cannabis is bad

“When you have more of a substance around there can be exposure and overdose,” said Goldstein. “That doesn’t make the substance bad.” Goldstein said this really boils down to a parenting issue—she advises parents to keep their cannabis at a distance where kids can’t reach it, or in a locked cabinet, the same as with other prescriptions. She said when a child is admitted to the ER because of cannabis ingestion, generally speaking, there’s no medical intervention necessary—you check their vital signs and, if they’re asleep, wait for them to wake up.

Haines-Saah told VICE in states where weed is legal, parents may also feel more comfortable calling poison control centers or taking their kids to the hospital for accidental cannabis ingestion because they know they aren’t going to get arrested. Form 2016 to 2017 in Alberta, there were 20 pediatric ER visits for cannabis ingestion compared to 700 for ingestion of Tide laundry pods.

Claim: Cannabis exposure can cause seizures, coma, and central nervous depression in kids

Verdict: Unlikely/misleading

Goldstein said a “coma” in the case of cannabis ingestion could mean the child or adult was sleepy for a few days. “It’s certainly not a coma like a head injury type of coma,” she said. “There’s no toxin and the child is going to wake up.”

She said in ten years of being a cannabis doctor, she’s seen two adult patients who took edibles with 100 mg of THC causing them to have seizures. “This is all about knowing what dose to take,” she said, noting California has regulated its edibles to max at 100 mg of THC per package. As for central nervous system depression, Goldstein said that just means sedation.

Claim: Three percent of pediatric cannabis ingestions reported to US Poison Control required ventilator support and landed in the intensive care unit. “Thankfully, no deaths. Cannabis ingestion can be life-threatening in children.”

Verdict: Misleading

Goldstein told VICE that ER doctors who are used to treating adults aren’t necessarily confident when treating children, which could result in unnecessary intubation. Working in critical care transport, she said she would pick up children who were on a ventilator or respirator and would often remove the tube to make it easier to transfer the patient.

“If you have a child in front of you and you are concerned about their respiratory system, you’re going to do what you think is necessary to stabilize that child’s breathing,” she said. “They will intubate the child and it may be unnecessary.”

Both Goldstein and Haines-Saah said it’s crucial for doctors not to spread misinformation about cannabis.

Goldstein said doctors have a bias against cannabis because they are taught in medical school that cannabis is a substance of abuse.

“Doctors are allowed to study the detriment of cannabis but not the benefit,” she said.

Haines-Saah told VICE tweets like Brown’s only further erode the mistrust between the public and the medical community.

“It’s putting up more barriers to people getting the evidence they need,” she said.

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