Scientists create breathalyzer to detect marijuana

PITTSBURGH — Scientists have created a new breathalyzer that may one day aid in enforcing DUI laws.

According to NPR, police currently do not have a device that can be used in the field to determine if a driver is under the influence of marijuana.
Researchers at the University of Pittsburgh are working on a solution, developing a breathalyzer that can detect tetrahydrocannabinol or THC, the main psychoactive compound in marijuana.

Current marijuana testing methods cannot be done in the field, since they rely on blood, urine, or hair samples. These tests also only reveal that the individual recently inhaled the drug, not that they are currently under the influence.

The breathalyzer looks similar to those used for alcohol, with plastic casing, a protruding mouthpiece, and digital display.

It works by using carbon nanotubes 100,000 times smaller than human hair. THC in the breath bind to tubes, causing a change in their electrical properties that can then be measured.

During lab tests, the device successfully detected THC in a breath sample that also contained carbon dioxide, water, ethanol, methanol, and acetone.

According to a university press release, researchers are planning to continue testing the prototype with the hope that it will move on to manufacturing.

NPR reports that one thing that may be an issue is correlating the breathalyzer's output to the driver's level of impairment.

With alcohol, a blood to breath ratio is used to determine drunkenness. But there isn't currently a ratio that links the level of THC in someone's breath to the amount in the blood, and then to exactly how impaired a person is.

Still, researchers say creating the device is at least one step toward making sure folks don't drive stoned.