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High On The Highway: Scientists Try To Build A Marijuana Breath Test

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High On The Highway: Scientists Try To Build A Marijuana Breath Test

High On The Highway: Scientists Try To Build A Marijuana Breath Test

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ARI SHAPIRO, HOST:

Here's a different type of police problem - being able to figure out when someone is driving while stoned. There's pressure to find a reliable way to do that in the areas of the U.S. that have legalized recreational marijuana. Washington state is one of them. At a lab at Washington State University - is working to develop a roadside marijuana breathalyzer. Reporter Tom Banse of the Northwest News Network paid a visit.

TOM BANSE, BYLINE: Let's suppose for just a second that you smoked a couple joints at a party and then got behind the wheel. This could be you.

ROB SHARPE: I'm Lieutenant Sharpe with the state patrol. The reason I stopped you today is I noticed you weren't able to stay in your lane. Any reason for that?

BANSE: That's Washington State Patrol lieutenant Rob Sharpe. He says driving behavior, coordination, odors, mannerisms and physical cues are some of the factors he uses to establish impairment by drugs.

SHARPE: OK, sir, what I need you to do right now is turn around and put your hands behind your back. You're under arrest for DUI.

BANSE: If this were real, the arresting officer might take you in for an hour-long evaluation by a drug recognition expert. He could seek a warrant and have your blood drawn at a hospital. The blood work typically takes weeks to come back. Washington State University chemistry professor Herb Hill heard about the challenges of nabbing drug-impaired drivers during a chance encounter with a colleague at a reception.

HERB HILL: And I said, well, why don't we have a breathalyzer for that? And then he says, well, there's - none exists. And I said, well, I think we can probably make one.

BANSE: And ta-da - well, actually it's taken years, but the goal is in sight. Hill takes me to his lab where he and colleagues are developing a handheld device that police officers can use to detect THC in breath. THC is the main psychoactive compound in marijuana.

HILL: This is the new prototype here.

BANSE: This is version 2.0?

HILL: This is 2.0.

BANSE: Hill says preliminary field testing with 30 human subjects this spring established that the device can detect THC in breath. Much more testing is ahead to look at potential variations among gender, race, body types and chronic users. Some marijuana activists fear this technology could lead to unimpaired drivers getting unfairly arrested. They point out that THC persists in the body long after the high has worn off. Hill's team recruits volunteers who buy their own weed and smoke it at their homes and then blow into the prototype.

HILL: We had to go through the human testing, the institutional board review, and it took us almost a year to get permission to do this.

BANSE: How hard was it to find these volunteers?

HILL: It's - it wasn't very hard to find the volunteers (laughter). We have a waiting list volunteers.

BANSE: The human guinea pigs get paid just over minimum wage to smoke their pot. Hill says the portable device he's developing may look like an alcohol breathalyzer but works differently inside. His team is modifying existing explosive detectors and chemical warfare sensors.

HILL: In the beginning, at least, this would not be used as evidential information. It would be used as screening information.

BANSE: Washington State Patrol's Lieutenant Sharpe says he's excited by the prospect of new tools to help him do his job better, but he says the pot breathalyzer must prove itself highly accurate before he'd adopt it.

SHARPE: Even if it's a preliminary device, we still need that level of accuracy and reliability for the trust and confidence. We're talking about people's rights, their liberties and freedoms.

BANSE: All of which points to it being several years at the earliest before you'd see a roadside breath test to identify stoned drivers. A few states have set legal limits for THC, but most have not. For NPR News, I'm Tom Banse in Olympia, Wash.

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