It may be possible to use a reliable breathalyzer, but it won’t be easy

University of Colorado Boulder researchers use this mobile lab, a white Sprinter van, to conduct research on the use of cannabis in the legal market. Credit: CU Boulder

A decade after Colorado and Washington became the first U.S. states to legalize recreational cannabis, law enforcement officials still face a vexing challenge: How can they tell if someone has recently smoked a joint or taken a candy bar and is unable to drive? ?

For alcohol, the answer is relatively straightforward: Since 1931, with the advent of the “slucometer” and 1954 with the invention of the more accessible and pure breathalyzer, police have measured ethanol (also known as ethyl alcohol) in breath, as a largely reliable device. Roadside Intoxication Scale.

New research shows that it’s not that simple with cannabis.

“In our pilot research, we found that in regular cannabis users, their breath about an hour after use didn’t look very different from a baseline measure on days they didn’t use at all,” said Cinnamon Bidwell, associate professor. In the Department of Psychology and Neuroscience at the University of Colorado Boulder. “This suggests that it will not be easy, and a lot of careful research will need to be done to get it right.”

A small “proof-of-concept” study, published in the journal Journal of Respiratory Research In May, it marked the first step in a unique collaboration between scientists and engineers at the National Institute of Standards and Technology (NIST) and researchers at CU Boulder.

Their goal: to develop reliable, standardized industry protocols for detecting cannabis impairment via breath — or at least determine if that’s possible at all.

NIST chemical engineers Tara Lovestead and Kavita Chirag pioneered this research with $2 million in grants from the U.S. Department of Justice’s National Institute of Justice. They partnered with Bidwell, a leading cannabis researcher. In September, NIST awarded CU Boulder $600,000 to help continue the research.

The project comes as a group of US startups have already begun marketing prototypes of cannabis inhalers to law enforcement, employers and cannabis users.

“There’s a large commercial establishment that says this is not only doable, but that it already exists. But the science isn’t there yet,” Bidwell said, noting that there are only about a half-dozen studies, some of which are industry-sponsored.

“Needle in a haystack”

Although blood alcohol analyzers are still imperfect, they have nearly a century of science behind them, including global standards for collection, breath analysis, and device calibration. None of this infrastructure exists to manufacture cannabis breathalyzers.

“Breathalyzers were created from studies of tens of thousands of individuals,” said Chirag, who did postdoctoral work in chemical engineering at the University of Colorado Boulder. “Breathalyzer research for cannabis was in the development phase in the 1930s and 1950s.” .

The chemistry of alcohol and cannabis is also different: unlike ethanol, which is exhaled in copious amounts in a gaseous vapor, the main psychoactive ingredient in cannabis (tetrahydrocannabinol, or THC) is carried in aerosols, small particles surrounded by fluid from deep within the lungs. .

NIST research has shown that individuals exhale 1 million times more ethanol in one breath than cannabis users who exhale tetrahydrocannabinol (THC) in 12 breaths.

“With THC, it’s like looking for a needle in a haystack,” said Lofstead, who earned her Ph.D. in Chemical Engineering from CU Boulder.

THC also remains in fatty tissue, appearing in blood and fluids for weeks, making it difficult to know whether a person used it an hour ago or days ago. (While some marketers of breathalyzers report that THC clears breath more quickly, making this an ideal way to detect recent use, there’s not enough data to definitively show that, Bidwell said.)

With alcohol, there is a clear relationship between blood concentration and impairment. But research has shown that more THC in the blood does not necessarily mean more intoxication.

To complicate matters, some people regularly use cannabis to treat medical conditions.

“I get emails all the time from lawyers trying to defend people whose blood tests indicate they have THC in their system but who insist they haven’t used it recently,” said Bidwill, the organization’s director, “It’s a big problem and a social justice issue.” Center for Health and Neuroscience Genes and Environment (CUChange).

Not ready to run in the elections

In the study, the researchers used a simple filter-based device to collect breath samples from 18 volunteers. Participants were asked not to use cannabis the day before giving their baseline samples or before the experimental session. Everyone was asked to purchase a specific strain of cannabis flower containing 25% tetrahydrocannabinol (THC).

One day, the CUChange mobile lab, a white Sprinter van, pulled into the participant’s driveway. (Because cannabis is illegal at the federal level, researchers are not allowed to handle or administer it, so Bidwell’s team developed a mobile laboratory system to evaluate the effects of cannabis use in the legal market.)

After giving blood and breath samples in the van, participants were asked to go home, use cannabis, and return to the van for cognitive and psychological tests for intoxication and breathing into the collection device.

Samples were shipped to NIST for processing and analysis via a technique called liquid chromatography with tandem mass spectrometry.

Surprisingly, only eight participants showed the expected increase in THC after cannabis use. In three breath samples after use, no THC was detected at all. In several other samples, breath THC levels after use were similar to or lower than baseline levels.

“Our results do not support the idea that detection of THC in breath as a single measure can reliably indicate recent cannabis use,” the researchers concluded.

They added that this does not mean that it is not possible.

In future research, the NIST team hopes to gain a better understanding of the chemical properties of THC, try other ways to detect it through breath, and develop standard reference materials that laboratories can use to calibrate their equipment.

The NIST-CU Boulder team plans to launch its next study soon, which includes at least 40 participants and more than a thousand breath samples from various time points to determine how quickly THC in the breath reaches its peak and dissipates. They also hope to learn whether comparing breath THC measurements over time might be useful for identifying or ruling out recent use.

“How can we take what we know from science and develop a reliable tool that can be used to safely protect people who use it and put an end to unsafe use?” Bidwell said. “That’s the ultimate goal.”

more information:
Kavita M Jeerage et al, THC in breath aerosol collected using an impact filter device before and after inhalation of the product in the legal market – a pilot study, Journal of Respiratory Research (2023). doi: 10.1088/1752-7163/acd410

Provided by the University of Colorado at Boulder

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