Episode transcript
Time stamps
0:30 - Welcome to this Allergy After Dark episode.
2:35 - The history of cannabis allergy.
5:00 - Occupational exposure.
6:02 - What are the symptoms of cannabis allergy?
9:24 - What specially within cannabis causes a reaction?
11:00 - Different ways a person may be exposed to cannabis.
13:50 - Food cross-reactivity with cannabis allergy.
16:55 - The risks of cannabis exposure in patients with asthma and respiratory allergies.
Announcer:
ImmunoCAST is brought to you by Thermo Fisher Scientific, creators of ImmunoCAP™ Specific IgE diagnostics and Phadia™ Laboratory Systems.
Gary Falcetano:
I'm Gary Falcetano, a licensed PA with over 11 years-experience in allergy and immunology.
Luke Lemons:
And I'm Luke Lemons with over five years of experience writing for healthcare providers and educating on allergies. You're listening to ImmunoCAST, your source for medically and scientifically backed allergy insights.
Today on ImmunoCAST, we have a very special episode, a very special After Dark episode for you around cannabis allergy, mainly because it appears that this allergy is increasing in prevalence. And it's often overlooked, I would say, by a lot of healthcare providers due to the sensitive nature of the subject and the legality of it in the past.
Gary Falcetano:
And I think that brings us to, it's a topic that we've discussed on our other After Dark episode, but it really is know how important it is and how essential it is to inquire about drug use. We mentioned on the last After Dark sexual activity, but really any of these taboo subjects when we're doing a social history on potential allergy patients.
Luke Lemons:
And as the substance becomes less taboo across America, right now there's actually 38 states that have it legal in some capacity, whether medical or recreational. For recreational of '24, more and more people are becoming exposed to cannabis, whether it's through, again, this recreational or medical use or secondhand exposure, occupational exposure in this growing industry. It was a substance that was illegal for so long and now it is more common.
Gary Falcetano:
Yeah, recently I saw some crazy numbers, Luke. I saw a paper that said 46% of the population in the world that's age 12 or older has used cannabis at least once in their lifetime.
Luke Lemons:
And that just speaks to the fact that there's a 50% chance that the patient in front of you, if they have asthma or if they have food allergies, which we'll talk about later in this episode, there's a chance they'll be exposed to cannabis and they may have a reaction.
Gary Falcetano:
Yeah, exactly. They will. Not to say that 18% had used it in the last year, so 48% ever in their lifetime, 18% in the last year, those are higher than any of the prevalence numbers that we typically see. So the awareness here is key.
Luke Lemons:
And when speaking about exposure, we're not just talking about smoking. We're talking about a lot of different ways that they may come in contact with it. So I think let's start with a history of cannabis and cannabis allergy. Gary, what can you tell me about the past?
Gary Falcetano:
You always go to me for the past. I don't know why that is. Is that our age gap?
Luke Lemons:
No, it's coincidental.
Gary Falcetano:
Like I remember the third millennium, right?
Luke Lemons:
Yeah, tell me about the third millennium.
Gary Falcetano:
Yeah, let me tell you about that, Luke. So it really is. Cannabis use has been documented way back to at least the third millennium BC. In the 1500s, the Spaniards used it in making rope and fabrics, and that's hemp which is really cannabis with a lower THC, and we'll get into that a little bit later. Allergy itself though, while I'm sure it's been around for as long as we've been in contact with cannabis, it wasn't described until 1971 in an Annals of Internal Medicine article where they discussed a 29-year-old female who had anaphylaxis symptoms after smoking a marijuana cigarette. This case was investigated pretty thoroughly using some pretty in-depth diagnostic at the time, and they were able to conclusively demonstrate that it was an allergy to something in the marijuana cigarette.
Luke Lemons:
And fast forwarding now to modern days, and this is where I'll talk, Gary. Sorry. The modern days.
Gary Falcetano:
Great.
Luke Lemons:
Yeah. We see a lot more exposure, specifically occupational exposure, whether that is through people who work in law enforcement, people who work in this medical industry. Even in paper, food, and textile industries, with hemp to your point earlier, with the Spaniards in 1500s using cannabis to make ropes. Cannabis has a lot of uses and because of that, there's a lot of opportunities for exposure.
Gary Falcetano:
An especially sad case was in the news recently where a woman who was working in a cannabis production facility who had a pre-existing asthma diagnosis actually suffered an asthma attack and died while at work. And it was really a wake-up call to healthcare providers and the cannabis industry that we really need to take occupational exposures seriously and try to prevent something like this from happening in the future.
Luke Lemons:
Yeah. At the end of the day, it is a weed and it is an allergen. And I'm glad you mentioned asthma because I have a bit of a crazy fact for you, Gary. So there was a survey conducted by Allergy and Asthma Network. They found that among the cannabis users, 58% had asthma, and 39% of those had uncontrolled asthma who were using cannabis, smoking.
Gary Falcetano:
That's amazing to me. I would hope they weren't all smoking and maybe they were using different forms. But in the past, we have actually seen smoking being used as a potential therapeutic. And we're going back to the past here, Luke. So certainly not anything that's recommended currently. But this says to me that healthcare providers, especially ones that are taking care of asthmatic patients, patients with asthma, that this really needs to be part of the social history. We need to ask about this.
Luke Lemons:
And these reactions that happen from cannabis allergy, Gary, are they only respiratory?
Gary Falcetano:
No, they're not. They're predominantly skin and respiratory symptoms that we see from the immediate-type hypersensitivity reactions. But we can see pretty much any symptom that we typically see with a type I hypersensitivity reaction.
Luke Lemons:
I think maybe we should level set on what we mean when we're saying cannabis allergy. So we are talking about both hemp and marijuana here.
Gary Falcetano:
Yeah. We're talking about cannabis and cannabis plants have different cultivars, different subspecies, but overall we're talking about cannabis. And depending on the level of THC, so hemp has a very low level of THC. I believe it's below 0.3%. And then cannabis has elevated levels of THC. And of course THC is the psychoactive component in cannabis.
Luke Lemons:
Yeah, and people aren't reacting to THC. So let's just be clear there, THC isn't the part of this plant that is causing allergic reactions, and neither is CBD. It is the pollen in the plant tissue. We do see some reactions more with CBD because CBD oil has a mixture of different parts of the plant in it, but it's not THC. It's not CBD. It is the organic matter, the pollen, the plant tissue.
Gary Falcetano:
Yeah, exactly. And no research to date has really implicated THC or the CBD itself as potential allergens, but as you said, all of the other substances found in the plant or pollen.
Luke Lemons:
Yeah. Again, just have to say a plant. It is a literal weed. And so it shouldn't be surprising that somebody is reacting to those parts of the plants.
Gary Falcetano:
Speaking of the allergens, if we have a suspected cannabis allergy, how does that get confirmed? We know you have to start with history. We've talked about that multiple times on this podcast. Once you've established a potential pretest probability that this is a cannabis allergy, can we test for it?
And right now, the testing options are really limited. There are some allergists that do what's known as puddle testing, basically taking a mortar and pestle and grinding up some of the patient's own cannabis and then doing skin testing with that. There's a lot of issues with that, and some of it from a legal standpoint, depending on the state you're in. Remember, cannabis is still a Schedule 1 substance federally. Schedule 1 says there's no medicinal use, so it can be difficult. There are some research assays that are in the works for both the hand-pull extract as well as some of the cannabis components. But as I said, those are all in research stages right now, but researchers are working to validate those and hopefully get us some form of readily available testing to confirm a cannabis allergy.
Luke Lemons:
And so it does fall on what we know from literature and from research when once we confirm that maybe somebody might with using history have a cannabis allergy, we have to turn to the papers because like you said, Gary, diagnostically, there really isn't a solid option right now. So looking at these research papers and looking at what's going into understanding this allergy, what do we know about what is causing specifically like let's say a protein or a component these reactions?
Gary Falcetano:
Up until now, we've identified five potential cannabis allergens, specific proteins that may cause symptoms or at least contribute to a positive whole extract test. And those are Can s 2. Remember, we talk about naming of components back in our pet components podcast. This is Cannabis sativa, right? Can s. Can s 2 which is a profilin. And next week or in the following weeks, we'll have a podcast specifically on food allergen components. And we'll take some deep dives into profilins and PR-10 proteins or Bet v 1 proteins. We find some of these in cannabis as well because it's a plant. So Can s 2 a profilin, Can s 5 is a PR-10 protein. I think one of the most promising components is Can s 3, which is a lipid transfer protein, and lipid transfer proteins are found in multiple plant sources, including peanuts, tree nuts, wheat. And these are all things that we can actually have a food allergy that's related to lipid transfer proteins. We can also have a cannabis allergy related to these lipid transfer proteins, and researchers are working through that right now.
Luke Lemons:
And so all these different components, all these different parts of the cannabis plant may contribute to the allergy. Again, we're still discovering stuff every day and we're doing research, but it's just really interesting because that lipid transfer protein that you had called out, it's heat stable. So even if somebody smokes cannabis, it doesn't destroy that protein. Speaking of which, let's go into the different routes of exposure that somebody could potentially come in contact with.
Gary Falcetano:
Sure. And I think typically when we're talking about weeds like cannabis is, we first think of pollens. And we are parts of the country that wild hemp or what is known as weedy hemp or wild cannabis is found. And that's generally in the center area of the country in the Midwest. And we've seen some research papers documenting the amount of cannabis pollen that's in the air in that area and relating it to respiratory symptoms in patients.
Luke Lemons:
And when it comes to these grow houses or these factories where people are growing weed for commercial use, those are mostly female plants so they don't really make pollen. I just want to put that out there that if you live next to one of these facilities in a state where it's legal, that might not be the pollen that you're reacting to.
Gary Falcetano:
I think there's a lot of other allergens that become aerosolized during the production process, which going back to that unfortunate death that we mentioned. That's part of the reason even though there's not a lot of high pollen counts there, there is a high amount of potentially of allergens in the air.
Luke Lemons:
When it comes to smoking, secondhand smoke or inhaled smoke, if you're allergic to cannabis, inhaling, it is a terrible, terrible thing to do. But even just walking around nowadays, there's people who smoke cannabis publicly and there's chance that somebody might react from that secondhand smoke.
Gary Falcetano:
Sure. And don't forget about vaping as another inhaled-
Luke Lemons:
Exactly.
Gary Falcetano:
... exposure route.
Luke Lemons:
Yeah. Again, because of the oils. Parts of the plant matter might be mixed in with that as well. And because these proteins don't get destroyed by heat, they exist. These allergens exist in the smoke and in the air.
Gary Falcetano:
Yeah. And another root of exposure is topical. We see a lot of CBD containing products, whether that be lotions or oils. And while the CBD, as we mentioned, hasn't been identified as potential allergen, they're often accompanied by many other parts of the plant that they've derived the CBD from. And those obviously could be potential allergens and end up with contact type allergy symptoms or even more type 1 hypersensitivity type symptoms.
Luke Lemons:
And then there's food. And I know what you're thinking, and we're not talking about brownies here or these edibles when it comes to cannabis. But you could have a reaction-
Gary Falcetano:
No, for sure.
Luke Lemons:
... by ingesting it. But this is really interesting though. Food cross-reactivity. Gary, if you want to talk a little bit about the types of foods that may cross-react with these allergens or with the cannabis.
Gary Falcetano:
Before we do that though, we should talk about edibles because that is definitely a potential root of exposure. And if you are allergic to cannabis, you can certainly have up to and including anaphylaxis from an edible, but I think what you're alluding to is the cross-reactivity in other foods. So we've seen research that, going back to that lipid transfer protein, the Can s 3, it has a high sequence identity with some lipid transfer proteins in other plant foods. So peanuts, peaches, wheat, tree nuts, all of these can potentially cause symptoms if you're cannabis allergic and if it's due to that lipid transfer protein.
Luke Lemons:
So what you're saying is, for example, if somebody is allergic to or sensitized and allergic to a lipid transfer protein and let's say peanuts, there's a chance that if they're exposed to cannabis, they will react.
Gary Falcetano:
Yeah, I think it can go both ways. It can be, depending on how they were initially sensitized and became allergic to that lipid transfer protein, it can happen from the original food that caused the sensitization or it can come from a cross-reactive food or exposure in cannabis, whether it be smoking or ingesting.
Luke Lemons:
And we're going to talk a lot about food components in the next episode. So if you're like, "Oh my gosh, what is Ara H? What are we talking about? Lipid transfer proteins?" Just stay tuned. We're really excited for the next episode. But going back to cannabis, when it comes to patients who do have food allergies, like we had mentioned earlier, 46% of people above 12 years old will try it. So if there is a patient who has a peanut allergy, it's worth talking to them about cannabis or any of these other foods that cross-react. Is that right, Gary?
Gary Falcetano:
Yeah, for sure. And again, not everybody who has a cannabis allergy, and we don't even know what that prevalence is yet, again, because of the nature of this subject, but we do think it's increasing in prevalence. I think it's a consideration, and especially when we start talking about those allergen components and we dive deep into them next week, especially if you have a sensitization to these lipid transfer proteins, then our index of suspicion should be raised. We should be aware that there could be potential cross-reactivity among these foods.
Luke Lemons:
So you're saying if let's say a patient is tested for allergen components using serological testing and they come back with elevated levels of lipid transfer proteins, then those are the patients we zero in on a little bit more.
Gary Falcetano:
Exactly. So they're peanut allergic and the lipid transfer protein and peanut is Ara h 9. They're hazelnut allergic. The lipid transfer protein is Cor a 8. If they're positive to those LTPs, then I think we need to have a in-depth discussion around potential cannabis exposure.
Luke Lemons:
And what about these patients with, let's say, asthma or respiratory allergies?
Gary Falcetano:
Yeah, that number still blows me away. 58% of those who are users actually have asthma. This is really an anticipatory guidance discussion. I think we've gotten pretty good in social histories with asking about smoking and even secondhand smoke and smoke in the house. For children, I think we're not as good. And that's been proven in some recent surveys as well about asking about exposure to potential cannabis smoke, whether that be firsthand or secondhand. So I think it's incumbent upon us as clinicians to include this in our histories.
Luke Lemons:
And again, our next episode is going to be all around components and food components. We'll have some resources on this episode's page. If you check the link in the description, we have a really interesting cannabis review paper that outlines a lot about this allergy, and that'll be available again on this episode specific page of ImmunoCAST. So at that, thank you for listening in to our conversation, and don't forget to subscribe and share. Thank you.
Gary Falcetano:
Thank you. We'll see you next time.
Announcer:
ImmunoCAST is brought to you by Thermo Fisher Scientific, creators of ImmunoCAST specific IgE diagnostics and Phadia Laboratory Systems. For more information on allergies and specific IgE testing, please visit thermofisher.com/immunocast. Specific IgE testing is an aid to healthcare providers in the diagnosis of allergy and cannot alone diagnose a clinical allergy. Clinical history alongside specific IgE testing is needed to diagnose a clinical allergy.
The content of this podcast is not intended to be and should not be interpreted as or substitute professional medical advice, diagnosis, or treatment. Any medical questions pertaining to one's own health should be discussed with a healthcare provider.
