EMILY KWONG: You're listening to Short Wave from NPR.
REGINA BARBER: Most people in the US now have access to some form of legal weed. But depending on the state, people could potentially be exposed to hidden health risks. Science journalist Teresa Carr did a whole investigation into this.
TERESA CARR: I'm really interested at the intersection of science and society.
BARBER: Teresa was reporting a story about medical marijuana use when she met Oklahoma resident Summer Parker, a medical marijuana sales and marketing professional who has Ehlers-Danlos syndrome, a disorder that affects the connective tissue and often causes serious chronic pain.
CARR: And she became addicted to opioids that were prescribed by her doctor for her pain. And she found that cannabis was both a way to help her overcome that addiction, and it also helps assuage her pain.
BARBER: But a couple years ago, she and her partner, Charles Urbina, started having unexplained health issues.
CARR: Summer had fainting episodes and stroke-like symptoms. Charles, who had a history of migraines, suddenly, they became unrelenting. He had to be hospitalized. He'd lost feeling in the side of his face. The doctors didn't have any real explanation for what was going on.
BARBER: When Charles's doctor suggested their weed could be contaminated, the couple dismissed it.
CARR: All legal products have to go through a testing process. And they get a Certificate Of Analysis, or a COA, that says it's, you know, free of all these contaminants and, you know, here's the chemical analysis of it. This is the THC profile.
BARBER: And THC, we should say, is short for tetrahydrocannabinol, the chemical responsible for most of cannabis's psychological effects. So in a feature article Teresa wrote for Undark.org, she explains that the cannabis plant is good at sucking up things from the environment. Research has shown it could be a tool for environmental cleanup of pesticides and heavy metals, but this special quality can also bring downsides. For instance, when Summer and Charles got some of the marijuana products they were using tested--
CARR: To their horror, they discovered that they were contaminated with both mold and some pesticides, and that those pesticides were associated with some neurotoxicity.
BARBER: Today on the show, how patchy weed regulations have failed to keep up with consumption and how it could be harming people's health. I'm Regina Barber. And you're listening to Short Wave, the science podcast from NPR.
BARBER: We're talking to independent health and science journalist Teresa Carr about patchy weed regulations across the US. We also have our own pharmaceuticals correspondent who's reported on this topic as well, Sydney Lupkin. Hey, Sydney.
SYDNEY LUPKIN: Hey.
BARBER: So Sydney, like, marijuana is now legal in some form, in many states. What's the difference on how weed is regulated versus, like, how pharmaceuticals are regulated in the US?
LUPKIN: Yeah, it is super, super different. And that's because weed, on the federal level, is illegal.
BARBER: Yeah.
LUPKIN: Pharmaceuticals, on the other hand, have to be approved by the Food and Drug Administration based on a very detailed process involving clinical trials and inspections to verify safety and efficacy. With weed, that robust federal system is not there, which means--
BARBER: Yeah.
LUPKIN: --that the states are basically having to figure this all out on their own and stand up their own mini FDAs and mini EPAs. And they do have a group that they have sort of formed together called CANNRA, which is basically a way for state regulators to communicate from state to state, with one another, to share data and what's working and what's not working. But that has its limitations because the standards are still kind of a patchwork.
BARBER: Yeah. I mean, this brings us back to, Teresa, this story in Oklahoma with Summer and Charles. You know, they got their weed tested, and you said that they found mold. They found other things. Was it that weed that was causing their health issues?
CARR: There's no way to know for sure. You can't prove cause and effect. One thing they did tell me is that when they stopped using that weed and switched to another brand, the problems that they had dissipated. So that's all you can say. They feel strongly that the two are correlated.
BARBER: And this wasn't just a one-time thing in Oklahoma. You wrote in your article about a testing lab manager, Jeffrey Havard, who tested 20 off-the-shelf marijuana joints there. So what did he find when he did all that testing?
CARR: He found that most of them were tainted with mold. And two of them actually had Salmonella. He also found that about 3/4 of them, you know, overstated the THC level, which is--
BARBER: Wow.
CARR: --as we discovered, fairly common.
BARBER: So, Teresa, does that mean that, like, the state's regulatory system for weed, in that case, failed?
CARR: One could say that. So, you know, there are contaminated products, you know, reaching the shelf. So from that perspective, you can say that the regulatory framework just isn't working to keep all the products that consumers are using and buying at dispensaries to keep those products clean.
BARBER: Hmm, OK. So you reported on how people who produce the weed have to arrange their own testing. Like, how has that affected the industry?
CARR: So I talked to people across the industry, everybody-- growers, lab managers, regulators, activists. And one thing that kept coming up was this issue of perverse incentives that encourage fraud. So you can see that pattern repeated over and over and over again. When a state legalizes marijuana, there's this big rush. A lot of people get into the industry. There's competition that makes things tough. And now, at this point, growers are struggling. So they need every single crop to pass. It's very important, or they go out of business. And generally speaking, their products are going to be much more profitable for them if they have a higher THC level. So the higher THC level, the more it sells for. So producers pay labs to test their products. And my investigation for Undark.org found that producers will choose labs that are looser about passing products for contaminants and that will give them higher THC levels. The flip side of that is that labs that are strict about their standards are going to lose business.
BARBER: You also looked at Oregon's regulations. Why did you look into that state in particular and, like, what did you learn?
CARR: I was really interested in Oregon for two reasons. One, they had recently opened a state testing lab, which kind of is a new trend among state regulators. So there was that. And there was also, their regulatory body had recently cracked down on several labs for THC inflation. In fact, most of their labs in the state they cracked down on for THC inflation. So it seemed a place to go where the regulators were actually taking some action and trying to do something about the problems that we were talking about.
BARBER: And, Sydney, you visited California to see how, like, it was regulating its huge weed industry. Like, what's going on there?
LUPKIN: Yeah, so state officials had been doing this, like, across several different state agencies. But a few years ago, they consolidated into the DCC, which is their Department of Cannabis Control. And they're basically tracking almost every step in the cannabis pipeline. Like, every plant has a tag and an ID.
BARBER: Wow.
LUPKIN: And it gets logged into a database. Like, weed manufacturers even have to report how many pounds of, like, plant trimmings they throw away.
BARBER: Wow.
LUPKIN: The labs have sort of had to keep up with this, like, really interesting and, like, creative industry where, like, you know, one day, they're like, oh, well, now we've got THC popcorn on the shelves. Like, how do you test that?
BARBER: Right.
LUPKIN: And they've got to figure it out. And that isn't to say that DCC is, like, doing everything perfectly because it's not. There was some reporting by the LA Times that there were still pesticides in the legal weed products, particularly in the vapes.
BARBER: Wow.
LUPKIN: So the department is, you know, evolving and trying to respond to that. And it's definitely upped its testing and enforcement in the last few years. So in 2024, there were over 60 weed recalls. And then this year, they've already had 80 weed recalls, and it's only October. And they've taken--
BARBER: Wow.
LUPKIN: --10 actions against laboratories so far this year.
BARBER: So more testing might mean more recalls, or more recalls may mean more contaminants. We don't know at this point. Let's talk about another study. So Teresa and Sydney, you both talked to Maxwell Leung, assistant professor at Arizona University, who did a study in 2022 about, like, that patchwork of cannabis regulations. Sydney, what did that report find?
LUPKIN: Yeah, so he said that there were over 600 contaminants that were regulated across the 30 states that had legalized cannabis at that time. But in each state, there were only between 60 and 120 contaminants that were being regulated. So in other words, different states were looking for different contaminants. I also asked Leung, you know, whether states testing for just more contaminants maybe had safer weed, and he said no.
BARBER: Wow.
LUPKIN: Because the research about how these contaminants in weed affect your health, you know, when you inhale them, for instance, it's not really well studied. So a state that might be testing for 300 things might not be testing for the one thing that is guaranteed to give you cancer someday. And a state only testing for a few contaminants might, in fact, be testing for that very bad thing. But without that research, which is hard because weed is still federally illegal, it's really hard to know what the worst contaminants are.
BARBER: Yeah, Teresa, is there anything you want to add to that?
CARR: The experts I talked to, including Max, are most concerned with inhaling the contaminants because as opposed to going through your GI tract, this is going to vape or the smoke is going directly into your lungs, and then it gets directly into your bloodstream. And when you think about it-- like, let's say, you're eating an apple, well, you can wash the apple. And if there's anything on it, you know, you can take it at least off the outside. But you don't wash your weed.
BARBER: Yeah.
CARR: And we really don't know how those inhaled contaminants are going to get into your system and affect you.
BARBER: Wow, OK. Teresa, you wrote in your article about how these contaminants could affect lungs. Like, how are mold and other things affecting people's health?
CARR: So when you think about mold, it's everywhere. And most forms are fairly harmless. But there are a few forms that are-- can cause serious health problems to humans, especially if you inhale them. And so that's one of the areas experts are most concerned about. And that's the idea that somebody, especially somebody with a compromised immune system, might inhale one of these toxic molds. And there have been case reports of people becoming seriously ill with pneumonia and serious lung respiratory problems from that. The other thing that scientists are worried about are heavy metals and pesticides that are toxic to the nervous system. For example, there's a type of pesticides that's commonly used in cannabis called organophosphates. It's a class of pesticides. And research has linked that to the onset and faster progression of Parkinson's disease, which is really a concern--
BARBER: Oh my gosh.
CARR: --because a lot of Parkinson's-- I think something like 40% of Parkinson's patients use cannabis to help with their symptoms of the disease.
BARBER: Wow. So Teresa, for consumers, then, who choose to partake, like, is there advice for them that you would give after doing all this reporting?
CARR: So products that don't pass in the legal market are often funneled into the illicit market. So when you buy illicit weed--
BARBER: Oh my gosh.
CARR: --you may be actually getting something that failed for mold, heavy metals, or pesticides. So I-- my best--
BARBER: Wow.
CARR: --advice I can give to people, even though it's imperfect, is to go to a dispensary and get a product through the legal market that has been through some sort of testing.
LUPKIN: Yeah, I definitely want to echo that. I talked to a weed cultivator who went from the illegal market to the legal one, and he described it as this sort of wild, wild west. And this guy was like, yeah, there used to be, you know, just a guy in a room spraying pesticides with the door closed
BARBER: [GASPS]
LUPKIN: --and you know, no protective gear.
BARBER: Wow.
LUPKIN: And that just doesn't fly in the legal market. So, you know, if you care about the people who are growing your weed, it's nice to go legal. And then just, if you're trying to be safer for you, it's a good idea to familiarize yourself with what your state regulations are and to regularly check recall lists, which are often published online. I think that that would be a good idea.
BARBER: Teresa, Sydney, thank you so much for talking with me today.
LUPKIN: Thank you.
CARR: Thank you.
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BARBER: This episode was produced by Berly McCoy, edited by Viet Le, and fact-checked by Tyler Jones. The audio engineer was Robert Rodriguez. Beth Donovan is our senior director. I'm Regina Barber. Thank you for listening to Short Wave from NPR.
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