As Legal Pot Proliferates, How Do We Test For Impairment?

8:05 minutes

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Law enforcement officers in Texas are noticing a rise in the number of cannabis-impaired drivers on the roads. The problem is, blood and urine tests take time to process—and they might also detect marijuana ingested days or even weeks prior. People in states legalizing pot want to be assured that stoned drivers will be as easy to catch as drunk ones.

[How older brains could benefit from marijuana.]

Lauren Silverman, the health, science and technology reporter at KERA News in Dallas, Texas, reports on efforts to develop a new kind of breathalyzer to catch pot-impaired drivers in the act. Plus, the secret to cows with climate-neutral burps and farts may be less about what they eat, and more about their inherited gut microbes.

Segment Guests

Lauren Silverman

Lauren Silverman is a Health, Science & Technology Reporter at KERA News in Dallas, Texas.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. Later in the hour we’re going to look at this week’s news about gravitational waves, exciting stuff. And colliding neutron stars that cause these. But first, as more and more states legalize marijuana consumption, whether for recreational purposes or medicinal use, law enforcement has a question.

How do we test drivers for pot-caused impairment? Can we make a breathalyzer for weed? Here with some solutions, plus other short subjects in science, is Lauren Silverman– health, science, and technology reporter at KERA News in Dallas, Texas. Welcome back, Lauren.

LAUREN SILVERMAN: Hey. Good to be here.

IRA FLATOW: So why is it so hard to figure out if someone’s driving high, like a simple breathalyzer test?

LAUREN SILVERMAN: Well, yeah. It’s actually a pretty big challenge. Standard breathalyzers don’t detect marijuana. And what officers typically do is run blood and urine tests. The problem with doing blood and urine tests, is that those tests are not sensitive enough to show whether someone just smoked marijuana right before they got in the car.

Or whether they smoked marijuana, or ate a cookie, or whatever it might be, a week, or even two weeks ago. So there’s this race to get an accurate and a fast testing device to the market. Hence everyone trying to come up with these marijuana breathalyzers.

And I visited one company in Oakland, California, that is creating a marijuana breathalyzer. It’s called Hound. And the device is small, and black, and it has a little tube sticking out of it. And you just blow through that tube a few times. And the CEO, Mike Lynn, says that in a few minutes it’s able to analyze and detect tiny amounts of THC– which is the active ingredient in cannabis– in someone’s breath.

IRA FLATOW: And you want to know is this something that they just took. Or as you say, not taken a month ago, because this stays in your blood. And here’s a Texas law enforcement official expressing that view.

SERGEANT MARK VINSON: I don’t want to know that there’s just something present. Just because there’s alcohol in somebody’s breath, or just because there’s marijuana shown– I need to be able to show and prove that there is impairment. That they can’t safely operate a vehicle.

LAUREN SILVERMAN: Yes. So that’s Sergeant Mark Vinson, and he’s a drug recognition expert. When I talked with him, he said it would be a game changer to have a device that could very quickly detect whether someone had just smoked or not. But the larger issue is, OK. If they just smoked, what does that really mean about whether they’re high?

And there’s no nationally agreed-upon standard. It’s not like, oh, the 0.08 blood alcohol level where people agree, OK, that means you’re impaired. There isn’t that number for marijuana.

IRA FLATOW: Yeah, it looks like they’re going to have to come up with something as all this expands through the states. Let’s move on to– but stay in the realm of criminal science. Because there are some new findings about what happens if you’re on trial and have a mental disorder of some kind. What’s going on here?

LAUREN SILVERMAN: Yeah. I thought this was fascinating. So criminal offenders who have a mental disorder, it turns out, are going to be judged more harshly if that disorder is genetic rather than environmental. The researchers who uncovered this are from the University of Missouri. They wanted to see whether it mattered if a criminal was born with a mental disorder, or had some environmental factor that caused it, like childhood trauma.

And they tested their hypothesis on two surveys with about 600 participants. They had the participants read one of two vignettes about an armed robbery. Basically, a 22-year-old guy goes into a bank, and he’s either arrested for robbing a bank, or for robbing a bank and killing the clerk. And then the subjects are randomly assigned one of three follow-ups, which describe this young man as having a brain disorder. And that brain disorder could either be genetic, environmental, or accidental.

And what they found, was that the offenders who developed mental disorders as a result of abuse, or some sort of accident, were seen much more favorably than those who had genetic disorders. In other words, if you’re born with a mental disorder you’re seen as deserving more blame and punishment, rather than people who had accidental.

IRA FLATOW: That hardly seems fair. Can the court system work around this bias somehow?

LAUREN SILVERMAN: I don’t know. I’m not sure. I mean it seems like at this point the research just gives some clues for public defenders about how they might want to craft their case when they’re talking about what their client did. And they might want to emphasize childhood abuse, and not genetic differences.

IRA FLATOW: Now our next story takes us to the problem of gassy cows. Flatulence. Burping cows. Is there anything we can try to get a lid on all that methane they emit?

LAUREN SILVERMAN: Yeah. This has been an ongoing problem. The second largest source of methane emission in the US is cow farts and belches. Belches are actually even worse than the farts. Unfortunately, cows are not great for the planet, but we still like to eat them– a lot of people.

And traditionally, the idea of getting them to emit less methane, people have focused on– How can we change the diets of the cows to maybe lower that amount? Because the cows churn out so much methane. Because in their digestive systems, the largest part of their stomach– the rumen– is filled with these microorganisms.

Bacteria, and more importantly for this topic, the archaea. And the archaea help break down and digest the plant cells that they’re eating. But in the process, they produce all this methane. So it turns out what they eat actually matters less than what microbes are in their stomach. And what microbes are in their stomach has to do with their genetics. So the breed of cow actually matters more in terms of how much methane is coming out, than whether they eat grass or corn.

IRA FLATOW: Could we do a microbiome transplant somehow?

LAUREN SILVERMAN: You want to volunteer?

IRA FLATOW: No. But we’ve heard about this in people– trying to change their microbiomes.

LAUREN SILVERMAN: Yeah. I don’t think the cow would enjoy that very much. But I think it would be even smarter, perhaps, if people say if we could alter some genetics. Or choose a breed that has the lowest emissions.

IRA FLATOW: And one last quick thing. Some insight into all those glowing stories about the health benefits of chocolate. What have we learned about that?

LAUREN SILVERMAN: Well, of course Halloween is coming up, and it’s the season of candy everywhere. So Vox decided to look at 100 studies that had been funded by the candy-maker, Mars. And found that– get this– of those studies, they overwhelmingly drew glowing conclusions about cocoa and chocolate.

IRA FLATOW: I’m shocked. Shocked.

LAUREN SILVERMAN: Yeah, right. It’s good for your heart, it boosts memory, it fights cancer, it brings peace to earth. OK. Maybe not the last one, but those are the types of claims we hear. And it turns out a lot of these studies are funded by the companies that make the products, like Snickers, and Three Musketeers, and all of that.

And that’s not unusual, but it is concerning. And the media coverage of chocolate mania doesn’t help. We’re responsible too. It seems to have influenced people’s buying habits. People are seeking out this dark chocolate.

IRA FLATOW: There are some studies that say one ounce of dark chocolate a day could help you a little bit. But you’re talking about going overboard here.

LAUREN SILVERMAN: Yeah. And it’s just that those studies are observational. So there needs to be a little bit more research still of the health claims about chocolate. There is some evidence that it can help with blood pressure, but it isn’t really conclusive in terms of the risk of heart attack and so on.

IRA FLATOW: Just in time for Halloween. Thank you, Lauren.

LAUREN SILVERMAN: Sorry about that.

IRA FLATOW: It’s quite all right. It’s good for me. Lauren Silverman. Health, science, and technology reporter at KERA News in Dallas, Texas.

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