Justice Today

What's Known and Unknown About Marijuana (Part Two)

January 31, 2024 National Institute of Justice Season 2 Episode 22
What's Known and Unknown About Marijuana (Part Two)
Justice Today
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Justice Today
What's Known and Unknown About Marijuana (Part Two)
Jan 31, 2024 Season 2 Episode 22
National Institute of Justice

Marijuana legalization poses many challenges — especially those related to drug chemistry and toxicology — for researchers, law enforcement, and policy makers. In the latest episode of Justice Today, NIJ Communications Assistant Josh Mondoro hosts a conversation with NIJ Scientist Frances Scott about marijuana toxicology, including comparing its effects to alcohol, measuring impairment, and maintaining public safety as more and more states legalize recreational marijuana. Read the transcript.

Listen to Part One.

Reading and Resources from NIJ:

Show Notes Transcript Chapter Markers

Marijuana legalization poses many challenges — especially those related to drug chemistry and toxicology — for researchers, law enforcement, and policy makers. In the latest episode of Justice Today, NIJ Communications Assistant Josh Mondoro hosts a conversation with NIJ Scientist Frances Scott about marijuana toxicology, including comparing its effects to alcohol, measuring impairment, and maintaining public safety as more and more states legalize recreational marijuana. Read the transcript.

Listen to Part One.

Reading and Resources from NIJ:

SPEAKER 1: Welcome to Justice Today, the official podcast of the Department of Justice's Office of Justice Programs. Where we shine a light on cutting research and practices and offer an in-depth look at what we’re doing to meet the biggest public safety challenges of our time. Join us as we explore how funded science and technology help us achieve strong communities.

JOSH MONDORO: Welcome back to the show, everyone. My name is Josh Mondoro, and I am your host for this episode. We're going to continue our conversation about marijuana. Last episode, we talked about the--kind of chemistry side of marijuana and what's involved with that. If you missed it, there's a link in the description. Please go check it out, it was a fantastic conversation. But today, we're going to switch gears a little bit. We're going to talk about the other half, we're going to talk about toxicology, and what that is and the issues and the questions that researchers face in that area. And joining us once again for this conversation, our expert on all things drugs, is Frances Scott. She holds a Ph.D. in chemistry from George Washington University and is a physical scientist with NIJ's Office of Investigative and Forensic Sciences. Frances, thank you again.

FRANCES SCOTT: Thanks, Josh.

JOSH MONDORO: For anyone who listened to part one, this will be slightly redundant, but for those who maybe who are here for the first time, just--let's start very quickly, just if you could define toxicology compared to drug chemistry, so we know our parameters for this conversation.

FRANCES SCOTT: Right. So we talked about drug chemistry the last time and that's when you're actually looking at the drug, at the substance, at the thing that your person will be going to ingest, or smoke, or rub on your skin, or whatever. And toxicology is looking at it actually once it's in your body, what are the effects on your body and, yeah, and whether--what can we detect in your body, what are the metabolites, which is what your body has done to the drug once it gets into your body. So those are the kinds of questions that we're looking at when--in forensic toxicology.

JOSH MONDORO: How it inter--how we interact with the substance.


JOSH MONDORO: Okay. That must be--it's my first thought, is that has to be very tough, right? Because everybody interacts differently with substances, right?

FRANCES SCOTT: Well, yes. You're kind of leaning ahead to--you know, some substances are pretty well-known, right? Like when your doctor prescribes something for you, it's based on, you know, I know that this is the types of reactions, that you need about this much medicine. And for most things, they don't even--unless you're a small child, they don't actually really need to know how much you weigh or how big you are because they're sort of standard dosing and we know this will do just fine for you and won't hurt you and so forth. It's a lot more complicated when we talk about things like marijuana which, of course, is our subject because you're talking about a plant, because you're talking about a whole bunch of different components, and each of those is going to have its own effect on the body and some of them may not be what's expected, some of them may, you know, there may be larger effects with combinations of things, or particular ratios of things, so, yeah, it's really complicated.

JOSH MONDORO: A lot of variables?


JOSH MONDORO: Outside of the plant itself?


JOSH MONDORO: What we're dealing with, right, okay. I have another question, but I think I would be jumping the gun there, so I'll hold it. Let's start here: with recreational marijuana being legalized in more and more places across the country, I imagine toxicology has a huge role to play at this point. So what does that look like right now? What's the landscape of toxicology when it comes to marijuana?

FRANCES SCOTT: Right. So in the world of forensic toxicology, we're sort of looking at a couple of--we look at antemortem, which is before death, and postmortem, which is after death. And when we talk about legalized marijuana, we're not so much worried, although we're starting to be more concerned with the postmortem piece of it, but that antemortem piece, let's talk about that for a minute. That's where you're going to be more familiar with the role of the forensic toxicologist because that's where we have things like DUI, driving under the influence, driving under the influence of drugs, DUID. And so that's where you're looking at those types of issues. And, yes, marijuana has been legalized in a lot of places, but in the same way that alcohol is legal to drink, but that doesn't mean you can go and drink as much as you want and then go get behind the wheel of a car. You know, we have laws around that. 

The problem is that we know, you know, getting back to what you were saying about things affect people differently, alcohol is really well understood. The—I’m going to use a couple big words: pharmacokinetics and pharmacodynamics. That's just what your body does to the drug and what the drug does to your body, okay? And so those are those two pieces. And those are really well-understood for alcohol. We understand the effects really, really well, we understand the elimination really, really well, you know. We can model that out, right? So it's relatively easy. And we have really good, you know, markers of impairment that correlate very nicely with different concentrations of alcohol in your blood. Or in your breath because you're used to maybe the breathalyzer at the side of the road.

JOSH MONDORO: Yeah, yeah.

FRANCES SCOTT: So that's all really well understood. The problem is that the picture is much more complicated for marijuana for a lot of reasons. There's the plant, which we talked about. The method of ingestion is--makes a big difference, so if it's smoked or inhaled, that has sort of a very well-known, like, sharp increase up to the peak sort of influence or effect, and then falls back off. Whereas if you're doing something like an edible, now you've got an hour plus until you get to that peak effect, and it's a more gradual curve.

JOSH MONDORO: It’s not a spike, really.

FRANCES SCOTT: It's not a spike. And it's not a…

JOSH MONDORO: You don’t hit the same high.

FRANCES SCOTT: Right. And it's not as tight of a timeframe. If you have chronic users versus infrequent users, they have very different concentrations correlated to different effects, right? So the same effect level, if you will, will be correlated with a very different concentration of THC in the blood of a chronic user versus an infrequent user.

JOSH MONDORO: So if someone uses chronically, it would take more to achieve the same effect? 

FRANCES SCOTT: Exactly. Yeah.

JOSH MONDORO: Right. More of the substance to hit the spike, or whatever.

FRANCES SCOTT: And--right, and then there's the fact that cannabinoids, you know, the components of marijuana that are psychoactive that do get you high, as well as the rest of them are fat-soluble, they're not water-soluble, right? So they stick around and then can kind of, you know, stay in your body a lot longer before being excreted, than some other, you know, like, water-soluble drugs.

JOSH MONDORO: Soluble--this is throwing me back to high school chemistry, and I don't remember what that means. Is that just they get…


JOSH MONDORO: Dissolved. Okay, okay.

FRANCES SCOTT: Like, what does--right? So oil and water don’t mix, right?

JOSH MONDORO: Yeah, yeah.

FRANCES SCOTT: Oily things dissolve in oil, and watery things dissolve in water, right? And so marijuana is like a fatty, kind of, loving thing, so…

JOSH MONDORO: Okay. So it just tucks away in there, it's not going anywhere soon, so it can stay around.

FRANCES SCOTT: It hangs out in your fat stores and, you know, may come out of it an opportune time, you know, depending on what kinds of testing you might have to have, so…

JOSH MONDORO: And the different, like, kind of--so does--I'm assuming different people, like, their body will onto it, right, their--their fat cells will hold onto it for longer versus another person versus a third person, right? Like, that must vary a lot.

FRANCES SCOTT: Right. And that goes back to the how often you use it, how did you use it. And all of that is almost beside the point because, to jump out a little bit I'll talk later about some research that NIJ has funded previously. You know, so we're sort of used to saying Delta-9 THC, that's the psychoactive component of marijuana, done and done. The problem is we've funded this research that pretty conclusively shows that the THC concentration in the blood is not particularly well-correlated with impairment for driving. So now you got questions of how, you know, with alcohol, you can measure the alcohol. Like, I can literally measure the ethanol in your blood and that's well-correlated with whether you're slurring or whether you can't drive in a straight line, et cetera. And those connections are not as clear for THC, in particular in marijuana.

JOSH MONDORO: So do we know what is or is that--that’s the outstanding question.

FRANCES SCOTT: That's one of the outstanding questions, yeah, is trying to figure out is there a good proxy, a good metric that we can use: if it's not Delta-9 THC, is there another one of those cannabinoids that is a good metric, or do we need to kind of move away from that? So with alcohol, we say we per se laws, that's the 0.08, right? And that if it's above 0.08, we don't have to sort of--if we demonstrate that your blood alcohol content is over 0.08, that's all I have to do to prove impairment, right? Because we--that's also well-understood. And maybe what we need to do is kind of get away from that idea that we can sort of have a number when it comes to marijuana and have that mean that you're impaired. And it may get into some different types of measures than we're used to doing. So maybe it's not a blood measure or a breath measure.

JOSH MONDORO: Right. And that's because we know enough at this point to know that there's so much variance compared to alcohol. Whereas like with alcohol, we've kind of seen enough to be like, "Well, there's some variance, however these, you know--generally speaking, these, like, effects will show up in everybody eventually, and at this level, it's a good enough number to draw?"


JOSH MONDORO: Okay. Got you. Got you. Well, yeah, there's a lot there that I'm sure we're going to get into when we're talking about research. But quickly before we get to what research NIJ's supporting for this, what are some of those things that--or maybe the difficulties that toxicologists are working with when they're trying to, like, measure impairment?

FRANCES SCOTT: Right. So that's the other piece, right? Is that toxicologists aren't necessarily--you know, a forensic toxicologist in a lab is not necessarily directly determining impairment, per se, right? Like, impairment for driving is a real specific thing, so toxicologists might be testifying on, you know, what the known effects of a drug are, you know, and there could be a case where they--you sort of put that together with, well, you know, cocaine makes people act erratic and Josh was acting erratic and here was this cocaine concentration, and so—you know, this jury can put that all together.

JOSH MONDORO: A plus B and C.

FRANCES SCOTT: Exactly. So it's a lot more complicated for impairments and so--and the other thing that we've learned is that the standardized field sobriety tests, SFST, and that's the ones that you've seen if you've watched any kind of, you know, reality police show or probably a lot of television. So that's the, you know, lift one foot, you know, sort of the balance, there's the toe to toe, you know, some of the touching your nose with one finger, stuff like that. And those tests are great for alcohol impairment, and they're not necessarily great at demonstrating impairment--of doing the complex tasks that are involved with driving, right? Like, so think about--I've got a kid who's 15 and is about to start driving. And so, it's sort of overwhelming for them right now, right? Because you think about all the things that you're doing.: there's pedals and there's potentially gearshift and there's the steering wheel and you're looking in the rear-view mirror and in front of you and on the sides, right? And this--there's a lot of data that you're synthesizing in order to drive your car down the road and not crash into a business like happened here in my neighborhood the other night. 

So, you know, we may need better tests, right? And we may need to measure different things in order to determine if someone is, as you said, for public safety we need to have people who are impaired off the road, right? You're not supposed to drive like if you've had, you know, I don't know, dental surgery or something and they've given you some drugs or whatever and it says, "Do not operate heavy machinery, right?" So there's this expectation that you need to not be impaired when you get behind the wheel in the same way that you shouldn't be over-tired and trying to drive, you know? They've demonstrated that that's really dangerous, right? So we have to figure out good ways to measure that impairment so that law enforcement can do their job, keep the public safe, you know, remove impaired drivers from the road. And alternatively, if that's not, you know, what's happening, like, maybe you just dropped something and reached down to get it and that's why you were swerving, and we're going to remind you to maybe pull off before you do that, you know, like, think that through a little better. But, you know, be on your way, right? Don't look at the damn phone while you're driving, et cetera.

JOSH MONDORO: Right. Right. Okay. Quickly, circular--or maybe not quickly, maybe this will be a rabbit hole, but circling back. With measuring impairment for alcohol versus marijuana, in this case, the effects, are they similar or not? And if they're similar, why do the tests not work? If that make sense. Or maybe like I'm missing something.

FRANCES SCOTT: Yeah. So, with marijuana, you have more--so alcohol, you know, those ones that I mentioned have a lot to do with sort of balance, kind of, your equilibrium. So, you know, at high enough alcohol levels, you're going to, you know, be in a blackout state. But even at those lower levels down there around the 0.08 and the 0.1 and so forth, it's more to do with you're not taking in that information appropriately. Maybe you're not seeing--maybe you're seeing more than one of the road in front of you, you know.

JOSH MONDORO: Like a little fuzzy?


JOSH MONDORO: All that kind of stuff?

FRANCES SCOTT: A little bit of the vision, a little, like…

JOSH MONDORO: You get a sense that that’s where somebody’s at.

FRANCES SCOTT: Yeah. So there's a lot…


FRANCES SCOTT: …of things that can be going on with alcohol. And then it can also slow your reaction time. So in that way, it can be like marijuana in the slowed reaction time. So with marijuana, it just--is the--it tends to be more of the--it interferes with your ability to focus on all of those different pieces of information, right. So you could even get sort of hyper-focused on one aspect of it. You know, maybe you look down to change the radio and then you're staring at the radio and it's so amazing, you know, and meanwhile, you're plowing through a bus stop. So it's a little bit--it's different types of effects and--that will impact your ability to drive in different ways, but still could both be impairing.

JOSH MONDORO: Right. And that's why those tests might not necessarily capture that, like…


JOSH MONDORO: …you would get locked in on the radio and plow into the bus stop. Right. Okay. Got you. Thank you for clarifying that. That's good. Okay. So, with all of that, there has to be tons of research that we could get into, but I'll narrow it down. What research would you like to highlight that NIJ is supporting in this area?

FRANCES SCOTT: Yeah, and there's a lot. So I am--and I probably should have said this on our last episode. I'm just highlighting a couple of our lines of research. NIJ is, to our knowledge, the largest federal funder of forensic science research. And so a lot of research that's done in these areas is done by us. NIDA, National Institute on Drug Abuse, does some when it comes to drugs and stuff, but really getting at these very criminal justice specific questions that's really NIJ's purview. 

So we previously supported Dr. Megan Grabenauer at RTI, and she was one who did this research of--specifically a--basically a clinical study of having people actually smoke marijuana. And then doing not only the standardized field sobriety tests, but also some other tests that have been suggested as perhaps more applicable metrics for marijuana impairment. And then they also took samples, biological samples, from the people involved. And that's where we get to--being able to sort of graph: here's this effect that is an impairment effect, and here's where the THC concentration is and those peaks don't line up with each other basically. And so that's the research that we've done and they've published on, and we've written stories about it that kind of highlights that challenge of what is the right thing, if we're going to try and look at a chemical in your blood, what's the right one to look at that's going to be correlated with impairment. 

We've also funded the Jeeragi Group, Kavita Jeeragi and Tara Lovestead at NIST Boulder. So the other NIST guys that's National Institute of Standards and Technology. And they're--they've been working on basically the idea of a cannabis breathalyzer. So cannabis is the plant, breathalyzer we're used to, and that's really what law enforcement, politicians--I mean, that's what they would love, right? Is, "Okay. Great. We're legalizing marijuana everywhere, but you're just going to be able to make us the thing that they can take in the field in exactly the same way they take an alcohol breathalyzer, right? That's what you're going to be able to do." Well, they're looking at all of the complicated science behind the vapor dynamics and so forth to see is that even reasonable to do it in a breathalyzer form? Because breathalyzer--the big advantage, right, is that it's non-invasive, right? You don't have to train police officers to be phlebotomists. Some jurisdictions have done that.

JOSH MONDORO: Really? Wow.


JOSH MONDORO: Oh, my gosh.

FRANCES SCOTT: Just another thing on their belt, right? Like taser, flashlight, gun syringe. Yeah. Great. All the things. So we'd like to avoid that because there's a lot of reasons why that's really complicated. So if we can get a--something that is non-invasive that you can literally do on the side of the road, that's obviously the ideal. Some complications of that, in addition to all the things we've already talked about, are that one of the major routes of administration for marijuana is inhaling it, right? Smoking it or vaping it. And so, then you need to look at what are the impacts, if you have that in your mouth, in your oral cavity, is that impacting what you get out on the breathalyzer? So we’ve been funding them.

JOSH MONDORO: Right. Versus like eating a gummy or something…

FRANCES SCOTT: Right. You’re most…

JOSH MONDORO: …or a brownie or whatever. Yeah.

FRANCES SCOTT: …likely to have that still in your—although there, you would have, you know, there are also researchers looking at oral fluid. And so then you have to look at all those factors.

JOSH MONDORO: So like a swab test kind of thing?

FRANCES SCOTT: Yeah. Like a—yeah, like a swab that you put in and it kind of soaks, you know, you want it to get saturated with the oral fluid in your mouth, and then that can be tested. That’s another non-invasive thing. 

We've funded Dr. Carl Wolf at Virginia Commonwealth University, and he's been looking at some of those non-Delta-9 THC compounds that we talked about the last time. So he's looked at like Delta-8, Delta-10, and their metabolites, and what does that look like in a urine drug test situation? So there's lots of folks who might be having urine drug testing done, probation, parole, some kind of child protective services situation, athletes, absolutely. And so military, so there's a--federal employees. So there's a lot of folks that it's important to know because again, there's, you know--with the hemp and the marijuana and all these other substances, you want to be really careful and be able to, you know, keep the public safe and not have anyone sort of accidentally, like, having an illicit substance either on their person or in their body, you know, that may not be their intention. 

And then we have a brand new award that's starting hopefully in January. And when I talked about some of those different, you know--what's the best metric? How do we look at this? It's a really unusual one, and it's looking at peripheral vision. So it's looking entirely outside of this idea. It's kind of saying, "Listen, we know all of these things are, you know--looking at THC and blood is maybe not the thing. Maybe that's not what's going to get us there. So let's see if we can find something that is, again, fits that bill of being a fieldable test that could easily differentiate or at least screen whether this person appears to be exhibiting signs of impairment, if this is consistent with impairment and whether this person needs to not be driving for the safety of everybody else.”

JOSH MONDORO: Does that get complicated if it could be a different substance? Like, will that require another test potentially to be like, "Okay. Like, we're--they're exhibiting a sign of impairment, but then impairment, what is the cause of that, right?” Was that another part of that?

FRANCES SCOTT: That's a great question. Yeah. From a certain standpoint, you're not allowed to drive impaired and it doesn't really matter what is causing you to be impaired, right? So from a certain standpoint, it doesn't--I don't want to say it doesn't matter, because that's the…

JOSH MONDORO: Less important than the impairment thresholds.

FRANCES SCOTT: It--you may not need--exactly. You may not need to differentiate it to that same level if what you're just trying to demonstrate is impairment. But it can be very complicated. So we have what are called DREs, Drug Recognition Experts, and those are law enforcement officers that are specifically trained to look for specific signs of drug--you know, drug induced impairment. And to the point of being able to say, I think it's a stimulant, I think it's, you know, an opioid, et cetera. One of my--one of my favorite stories is my brother is an albino. Albinos have vertical nystagmus. That means their eyes shake back and forth. Sorry, that's horizontal. So their eyes shake back and forth all the time. Well, guess what? One of the…


FRANCES SCOTT: …indicators for drug impairment is.


FRANCES SCOTT: Yeah. Yeah. So there's lots of things that can complicate that. But if what you're looking for is being able--you know, because--you got to realize, in order to do a field test, you have to have had a reason why someone was demonstrating signs of impairment in their driving, right? Like someone was driving erratically in some way. There was something that caused you to be now in the situation of having that field test done, you know, in most scenarios. I mean, I'm not a law enforcement officer, but that's generally kind of how that works. And so once you've--now, we're at that point. So now, we're at the--okay. We have sort of these, these markers, these clues that are show--that seem to indicate that you should maybe not be driving, and now what other evidence is there sort of for against that.

JOSH MONDORO: Got you. That makes sense. Circling--I had one other thought with the potential breathalyzer situation. Does it matter if, like--because we had--you had mentioned too, there's like the breathalyzer and then there's also potential, like, oral fluid test. I'm assuming, like, that they will be very different depending on the, like--am I using the word right? Matrices, that you’re testing, right? The different of—whether it’s fluid oral, whatever. And wherever that belong or wherever you’re pulling it from the body that it could maybe have different levels. Is that accurate or no? Is that a complication, or no?

FRANCES SCOTT: Yeah. Yeah. For sure. So like when we talk about alcohol, we say 0.08, that's the percentage in your blood. It's actually a completely different number in your breath. It's just that it's a known sort of multiplier of we take this number in the breath that--and multiply it by this, and that correlates with the amount in your blood. So yeah, you definitely--you know, depending on whether you're looking at oral fluid and you're looking at some, you know, per milliliter of liquid that you're looking at or, you know, when you're talking about breathalyzer, you've got liters being--you know, how many liters of exhalation are passing through the breathalyzer, right? So, yeah. There's a lot of--there's definitely going to be different numbers and different metrics involved with those.

JOSH MONDORO: Got you. I think this might be irrelevant. This might just fall into that same category of the irrelevant thing. With the--like, so someone could in theory be not impaired, right? But still have marijuana present in their system since it tends to stick around for a while. Is that also a complication that is mattered or, again, not really our--not problem, but that's the word I'm going to use here, but not as important as like, are they impaired? That's what we need to figure out because of public safety and everything.

FRANCES SCOTT: Right. I mean, it's definitely an important question. And every--in the same way that jurisdictions, you know, states can decide that they're going to legalize marijuana, states can make laws about driving in their state, right? So we say 0.08, that's what it is in Virginia and most places. Some places are still on a 0.1. It was 0.1 when I--when I was young, it was 0.1 and then it became 0.08. And so there may be jurisdictions that have already put into place, or are considering, that same kind of per se law for marijuana. So they may just say, "Here's the number. If you're above this, doesn't matter, right?" So it--it's a little bit of, it depends on what--and that's kind of always the question when we're in forensic science, right? Is that interaction of science, what we can say using the science, and what that means from a legal standpoint and where that intersection is.

JOSH MONDORO: Yeah. And then how that circles back to: How do we carry--like, for law enforcement people who are going to be in these situations in the field, how do they have the knowledge and the tools to be able to carry that out?


JOSH MONDORO: Yeah. Yeah. Man, I learned a lot, as always. Thank you so much for sharing everything with us today. I know our listeners must have learned a lot as well. So thank you for your time. Appreciate it.

FRANCES SCOTT: Thanks, Josh.

JOSH MONDORO: Listeners, yes. Thank you for staying tuned and for listening with us today. If you like what you heard, please follow us on Apple, Spotify, or wherever you get your podcast, and stay tuned for future episodes from NIJ.

SPEAKER 2: To learn more about today's topic or about NIJ, visit the links in the episode description and join us for new episodes every month. 

Opinions or points of view expressed in this episode represent a consensus of the authors and do not necessarily represent the official position or policies of the U.S. Department of Justice. Any products and manufacturers discussed in this episode are presented for informational purposes only and do not constitute product approval or endorsement by the U.S. Department of Justice.

Explaining forensic toxicology
Impairment and DUIDs
Toxicology research projects and the potential for a marijuana breathalyzer