Skip Navigation

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

Breakthroughs.KERA.org 1

A quartet of Western states and the District of Columbia have legalized recreational marijuana, and voters in a half-dozen more states may vote on pot legalization in 2016. That’s leading law enforcement officials and entrepreneurs to try to come up with better ways of testing for driving while stoned.

Police usually spot impaired drivers by noting driving behavior, coordination, mannerisms and physical cues. But while a handheld breath test can quickly determine whether someone is legally drunk based on ethanol in the breath, there’s no instant test for marijuana intoxication.

In Washington state, which is one of 18 states that has set limits on marijuana intoxication while driving, law enforcement can seek a warrant for a blood draw to test for THC, the main active ingredient in marijuana. But it can take weeks for results to come back from the toxicology lab.

With more Washington state drivers being arrested with marijuana in their systems since the state legalized recreational marijuana, there’s growing need for a fast way to identify impaired drivers and get them off the road.

Herb Hill, a chemistry professor at Washington State University in Pullman, heard about the challenges of nailing drug-impaired drivers from a colleague who was a political science professor. “I said, ‘Why don’t we have a Breathalyzer for that?’ He said none exists,” Hill said. “I said, ‘We can probably make one.’ ”

So Hill and his colleagues are trying to develop a hand-held device that police officers can use to detect THC in breath. Preliminary field testing with 30 human subjects this spring established that the device can detect THC in breath, Hill said. Much more testing is ahead to look at potential variations among gender, race, body types and amount of use.

Hill’s team recruits volunteers who buy their own weed, smoke it at their homes and then blow into the prototype.

“We had to go through institutional board review,” Hill said, referring to federal restrictions on research involving marijuana. “It took us almost a year to get permission to do this.”

“It wasn’t very hard to find the volunteers,” Hill added. “We have a waiting list of volunteers.”

The human guinea pigs get paid just over minimum wage to smoke their pot.

Hill said the portable device may look like an alcohol Breathalyzer but works differently inside. His team is modifying existing sniffers used at airports to detect explosives and by the military to alert to the presence of chemical warfare agents. The technology is called ion mobility spectrometry.

“In the beginning at least this would not be used as evidential information,” Hill explained. “It would be used as screening information to help the officer say he should take a blood sample now.”

Jake Yancey, a police officer in Tumwater, Wash., said he would be “super excited” to get a detector that he hopes could “drastically speed up” the process of confirming or ruling out a person’s possible marijuana impairment. But a pot breath test must prove itself highly accurate before Washington state would adopt it, according to Lt. Rob Sharpe, head of the impaired driving section at the Washington State Patrol.

“Even if it is a preliminary device, we still need that level of accuracy and reliability for trust and confidence,” Sharpe said. “Regardless where it comes into play in that arrest decision, we’re talking about people’s rights, their liberties and freedoms. We need to be accurate.”

All of which points to it being several years at the earliest before you’d see a roadside breath test to identify stoned drivers.

Sharpe said a pot breath test might not even be the chosen answer. He said other companies and research teams are working on alternatives, including cheek swabs or a saliva test, a smartphone-based eye scan, or analyzing sweat on a person’s skin.

Since legalizing marijuana use for adults, Washington and Colorado have both set legal limits for THC intoxication at 5 nanograms per milliliter of blood. Oregon and Alaska have not established a legal THC limit beyond which a driver is presumed to be impaired.

Some marijuana activists have expressed fears that 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. The effects of weed are also different in different people, including between infrequent versus chronic smokers.

Indeed, there is no universal agreement on how much THC is impairing — countries in Europe have set legal limits at 2 to 7 nanograms.

As part of the next rounds of human testing of the marijuana breath tester, the Washington state researchers want to correlate breath readings of THC with simultaneous blood draws and measurements. This could help to establish how long THC lingers in the breath after initial consumption.

Early on, the WSU professors took their idea to Chemring, a Falls Church, Va., instrument maker that agreed to pay for the R&D and will have the commercialization rights.

The Chemring-WSU team is by no means alone in trying to perfect a marijuana breath test. Competitors include Lifeloc Technologies of Colorado, which already makes alcohol testers, and Cannabix Technologies Inc. of Vancouver, British Columbia, has shown off an initial prototype at conferences. There are reportedly several research teams at work in Europe as well.

Copyright 2015 NWNews. To see more, visit NWNews.

Transcript :

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. Transcript provided by NPR, Copyright NPR.