Pot Brownies More Toxic Than Smoke?

F. Perry Wilson, MD, MSCE


March 27, 2019

Welcome to Impact Factor, your weekly hit of commentary on a breaking medical study. I'm Perry Wilson. This week, we get Rocky Mountain high with a study appearing in the Annals of Internal Medicine, which examined the rates of Colorado emergency department (ED) visits for cannabis exposure over a 5-year period.[1]

It will be news to none of you that Colorado legalized recreational marijuana use in 2014, a single event that set epidemiologists salivating. Here was as close to a randomized trial of pot smoking that you'd ever get. Would the state plunge into chaos and ruin, or would a flourishing of libertarian capitalism propel it to new heights?

Well, the apocalyptic visions didn't come to pass. In fact, recent data suggest that pot use among teens has fallen more sharply in Colorado than in the rest of the United States, which goes to show you that once your parents start doing something, it isn't cool anymore.


But according to this study, ED visits attributable to marijuana have ticked up—by about a factor of 3.

Source: Monte AA, et al.[1]

Researchers performed direct chart reviews on over 10,000 emergency admissions at a single urban Colorado center to figure out what role pot had to play in the presentation and what type of pot was to blame. They started by filtering roughly 450,000 ED visits using ICD-9 codes associated with marijuana, leaving 9973 visits to directly review.

Republished with permission of Annals of Internal Medicine

So, right off the bat, we need to be careful here. The uptick in admissions after the 2014 legalization may be because more people were using marijuana, but it may simply be due to the fact that people were more openly admitting it or providers were more comfortable asking about it, leading to increased medical coding.

Where the study really gets interesting is in the type of cannabis that brought people to the ED. Around 10% of the ED visits were from people ingesting so-called "edibles."

Okay. For squares like me, you can get cannabis in a couple of ways. You can smoke the cannabis flowers, which is the standard method, or you can eat food with THC or cannabis baked in—"edibles." Think pot brownies. And pot gummy bears.

Now, 10% of the ED visits were for edibles, but only 0.3% of Colorado cannabis sales were for edibles.

Source: Monte AA, et al.[1]

That means that edibles were overrepresented in the ED by a factor of 33. That's crazy. But it might make sense.

Edibles have a delayed onset of action compared with smoked marijuana—typically 30 minutes compared with 10 minutes. And they stay in the system longer—around 12 hours for edibles compared with 4 hours for smoked marijuana. That means that people might be "redosing" their edibles because they aren't feeling it yet, only to get into trouble later.


There's another little gem of data in this study.

Source: Monte AA, et al.[1]

Of the patients in the ED for edibles, 41% lived outside of Colorado, compared with just 6.6% out-of-staters for smoked marijuana. This implies that marijuana tourists, eager to try out the various forms of pot on display, might be driving some of these findings.

So, what have we learned? The big take-home for me is that edibles—those cute, THC-filled gummy bears, the salted-caramel pot brownies—are potentially way more dangerous than the old-fashioned joints that were the staple of marijuana consumption prior to legalization.

In other words, when it comes to recreational marijuana, well, put that in your pipe and smoke it.


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