Why Legal Weed Isn’t Always Safe

Marijuana is decriminalized or legal in some form in multiple states. But, because it’s illegal on the federal level, states have had to build their own regulatory infrastructure. Without a centralized body to guide them, regulations in one state can look vastly different from those in another. For more on the scope of the issue, Short Wave host Regina G. Barber https://www.npr.org/people/1082526815/regina-g-barber talks to independent science journalist Teresa Carr https://undark.org/author/teresa-carr/ and NPR pharmaceuticals correspondent Sydney Lupkin https://www.npr.org/people/825275572/sydney-lupkin. Read more of Teresa’s reporting on state marijuana testing https://undark.org/2025/07/16/cannabis-testing-reform/, and more of Sydney’s reporting on the ways California is trying to make weed safer https://www.npr.org/2025/03/24/nx-s1-5239985/marijuana-recreational-weed-safe-contaminants-california. Interested in hearing more science behind consumer products? Email us your question at [email protected] mailto:[email protected] – we may feature it on an upcoming episode! Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave http://plus.npr.org/shortwave. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

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• 0:00Speaker 00

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• 0:18Regina Barber?

  Hey, short waivers. Emily Kwong here. I have a confession. We read every single review that you leave us on Apple Podcasts, on Spotify, on whatever platform you use. We can't make this show without you. You are our other half. You are our soulmate. You are the reason we get up in the morning. And we kind of need to know what you think of the show in order to do our job well. So get yourself over to your podcasting platform. Leave us a review. Put into words what this show means to you so that other people can find it. Thanks. OK, here's the show. You're listening to Short Wave from NPR. Most people in the US now have access to some form of legal weed.

• 1:02Regina Barber?

  But depending on the state, people could potentially be exposed to hidden health risks. Science journalist Teresa Carr did a whole investigation into this.

• 1:10Speaker 02

  I'm really interested at the intersection of science and society.

• 1:14Regina 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.

• 1:30Speaker 02

  And she became addicted to opioids that were prescribed by her doctor for her pain. And she found that cannabis was both the way to help her overcome that addiction and it also helps assuage her pain.

• 1:44Regina Barber?

  But a couple of years ago, she and her partner, Charles Arbina, started having unexplained health issues.

• 1:50Speaker 02

  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 a side of his face. The doctors didn't have any real explanation for what was going on.

• 2:07Regina Barber?

  When Charles's doctor suggested their weed could be Be contaminated, the couple dismissed it.

• 2:12Speaker 02

  All legal products have to go through a testing process. And they get a certificate of analysis or 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.

• 2:26Regina 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.

• 2:56Speaker 02

  To their horror, they discovered that they were contaminated with both mold and some pesticides. And that those pesticides were associated with some neurotoxicity.

• 3:10Regina 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.

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• 4:51Regina 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 Lepkin. Hey, Sydney.

• 5:03Speaker 03

  Hey.

• 5:04Regina Barber?

  So Sydney, marijuana is now legal in some form in many states. What's the difference on how weed is regulated versus how pharmaceuticals are regulated in the US?

• 5:15Speaker 03

  Yeah, it is super, super different. And that's because weed on the federal level is illegal.

• 5:21Regina Barber?

  Yeah.

• 5:21Speaker 03

  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 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 formed together called CANRA, 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.

• 6:06Regina Barber?

  Yeah. I mean, this brings us back to Teresa, the story in Oklahoma with Summer and Charles. 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?

• 6:22Speaker 02

  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.

• 6:40Regina 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?

• 6:52Speaker 02

  He found that most of them were tainted with mold, and two of them actually had salmonella. He also found that about three-fourths of them overstated the THC level, which is, as we discovered, fairly common.

• 7:07Regina Barber?

  So Theresa, does that mean that the state's regulatory system for weed, in that case, failed?

• 7:14Speaker 02

  One could say that. So there are contaminated products reaching the shelf. So from that perspective, you could 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.

• 7:31Regina Barber?

  Okay. So you reported on how people who produce the weed have to arrange their own testing. How has that affected the industry?

• 7:39Speaker 02

  So I talked to people across the industry, 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. It 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

• 8:19Speaker 02

  it sells for. So producers pay labs to test their products. And my investigation for undoc.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.

• 8:42Regina Barber?

  You also looked at Oregon's regulations. Why did you look into that state in particular? And what did you learn?

• 8:48Speaker 02

  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.

• 9:20Regina Barber?

  And Sydney, you visited California to see how like it was regulating its huge weed industry. Like, what's going on there?

• 9:27Speaker 03

  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.

• 9:47Regina Barber?

  Wow.

• 9:47Speaker 03

  And it gets logged into a database. Like, weed manufacturers even have to report how many pounds of like plant trimmings they throw away.

• 9:55Regina Barber?

  Wow.

• 9:55Speaker 03

  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?

• 10:08Regina Barber?

  Right.

• 10:09Speaker 03

  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. 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 10 actions against laboratories so far this year.

• 10:45Regina 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 Lung, assistant professor at Arizona State University, who did a study in 2022 about like that patchwork of cannabis regulations. Sydney, what did that report find?

• 11:09Speaker 03

  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 lung, you know, whether states testing for just more contaminants maybe had safer weed. And he said, no.

• 11:37Regina Barber?

  Wow.

• 11:38Speaker 03

  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.

• 12:08Regina Barber?

  Yeah, Teresa, is there anything you want to add to that?

• 12:11Speaker 02

  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, the 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.

• 12:36Regina Barber?

  Yeah.

• 12:37Speaker 02

  And we really don't know how those inhaled contaminants are going to get into your system and affect you.

• 12:42Regina Barber?

  Wow. Okay. Teresa, you wrote in your article about how these contaminants could affect lungs. Like, how are mold and other things affecting people's health?

• 12:52Speaker 02

  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 is a type of pesticides that's commonly used in cannabis called organophosphates.

• 13:36Speaker 02

  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. 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.

• 13:58Regina 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?

• 14:06Speaker 02

  So products that don't pass in the legal market are often funneled into the illicit market. So when you buy illicit weed.

• 14:15Regina Barber?

  Oh, my gosh.

• 14:16Speaker 02

  You may be actually getting something that failed for mold, heavy metals, or pesticides. So I, my best 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.

• 14:34Speaker 03

  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 and, you know, no protective gear.

• 14:51Regina Barber?

  Wow.

• 14:52Speaker 03

  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.

• 15:14Regina Barber?

  Teresa, Sidney, thank you so much for talking with me today.

• 15:18Speaker 03

  Thank you.

• 15:18Speaker 02

  Thank you.

• 15:20Regina Barber?

  This episode was produced by Burley 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.

• 15:44Speaker 04

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