Pitt researchers develop marijuana breathalyzer | TribLIVE.com
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Pitt researchers develop marijuana breathalyzer

Deb Erdley
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Pitt professors Alexander Star and Ervin Sejdic display the marijuana breathalyzer their research team developed.

With more and more states legalizing medical and recreational marijuana, sooner or later some bright scientist had to invent a marijuana breathalyzer.

Now it appears researchers at the University of Pittsburgh may have just walked to the head of the class.

A Pitt spokesman said a team from the university’s chemistry department joined researchers from Pitt’s Swanson School of Engineering to develop a breathalyzer that can measure the amount of tetrahydrocannabinol or THC, the psychoactive compound in marijuana, in a user’s breath.

Although they have yet to commercialize their device, Pitt spokeswoman Maggie Pavlik said the group that recently published its findings in the journal ACS Sensors has patented the device that was developed using nanotechnology.

In this case, carbon tubes 100,000 times smaller than a human hair are used to measure THC molecules. When a user breathes into the device, the molecules bind to the nanotubes and create a change in their electrical properties that can be measured.

With recreational marijuana legal in 11 states and the District of Columbia, and medical marijuana legal in another 22 states including Pennsylvania, law enforcement agencies face such issues regularly.

In Pennsylvania, where more than 100,000 people have marijuana cards, state police rely upon breathalyzers and blood alcohol tests to determine alcohol impairment.

“But if a trooper suspects someone is under the influence of marijuana, they may call in a certified drug recognition expert or DRE who has been trained to look for things like involuntary movements of the eyes and other physical signs that someone is under the influence of marijuana or other drugs,” said Pennsylvania State Police spokesman Ryan Tarkowski.

If those factors suggest drugs may be involved, officers have the option of seeking blood or urine samples to verify their suspicions.

Tarkowski said individuals arrested and charged with being under the influence of drugs other than alcohol are counted among those charged with DUI, or driving under the influence.

“Possession of a medical marijuana card does not preclude any one from being charged with driving under the influence,” Tarkowski said.

Back at Pitt, researchers credit technological advances for their progress in developing the marijuana breathalyzer.

Sean Hwang, a doctoral candidate in chemistry at Pitt and the lead author of a new article about the device in the journal ACS Sensors, said the carbon nanotubes the team used weren’t even available until recently.

“We used machine learning to ‘teach’ the breathalyzer to recognize the presence of THC based on the electrical current’s recovery time, even when there are other substances, like alcohol, present in the breath,” he said in a press release describing the group’s work.

Their research occurred with the oversight and permission of the U.S. Drug Enforcement Agency.

The team took three years to develop a handheld model of the device that could be used in the field.

Although law enforcement agencies can rely on years of research to document the blood-alcohol levels where impaired driving occurs, there is little such research involving THC.

In a 2017 report to Congress, the National Highway Traffic Safety Administration conceded it has little research to rely upon when it comes to marijuana-impaired drivers and the level at which impairment begins.

Alexander Star, a Pitt professor who holds a doctorate in chemistry with a secondary appointment in bioengineering, leads the Star Lab which participated in the project. The team partnered with Ervin Sejdic, PhD, associate professor of electrical and computer engineering at the Swanson School of Engineering, to develop the prototype.

Star said it will allow researchers to begin working to determine when and at what levels of THC impairment begins.

“It probably also depends on whether a person is a regular user and the person’s size. The presence of THC in breath doesn’t mean the person can be impaired,” Star said. “We’ll try to measure that in future research.”

Deb Erdley is a Tribune-Review staff writer. You can contact Deb at 724-850-1209, [email protected] or via Twitter .

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