Scientists say a marijuana breathalyzer is in the works

A device that can detect the chemical in cannabis responsible for its psychoactive effects could work as an early prototype for a breathalyzer-type tool to test for marijuana, according to a recent study.

Researchers at UCLA and a UCLA startup called ElectraTect are testing a "cannabinoid fuel cell" that they say provides a key foundation for one day developing a marijuana breath analyzer similar to ones that exist to test for alcohol on a person's breath.

The laboratory device, described in a paper published online Sept. 12 in the journal Organic Letters, is able to detect THC and measure the psychoactive component's concentration in a solution. This type of technology could provide a more accurate gauge of how much THC is present in a person's system compared to existing methods, the researchers said.

Testing with saliva, blood or urine can sometimes return skewed results, the researchers said, because THC can remain in bodily fluids for up to several weeks after a person has smoked marijuana.

"As such, there exists a need for a fair forensic tool capable of detecting THC in the short window of impairment," the scientists wrote in the study. "This is particularly true in states and countries where marijuana has been decriminalized or legalized, given that traditional testing could lead to fines, prosecution, imprisonment, or loss of employment, even if the individual is not impaired at the time of testing."

Cannabis use has been associated with cognitive and motor impairment, and some countries such as Canada have instituted THC cutoffs for drivers based on the psychoactive compound’s concentration levels in the blood.

The UCLA-built device works similar to commonly used alcohol breath analyzers. Samples in a solution undergo oxidation, a process that strips a molecule of hydrogen from THC and generates an electric current that can be measured. The strength of the current corresponds to how much THC is present in the sample: the stronger the electric current, the higher the concentration of THC molecules, the researchers said.

The electrochemical oxidation process was first detailed by the researchers in a study published in April 2020 in the same journal.

The scientists are now trying to miniaturize the technology to create a handheld device that can be used for rapid and inexpensive marijuana testing. The researchers said future devices could test for both alcohol and THC. The breath analyzers could also be connected to a vehicle's ignition and help cut down on impaired driving by preventing a car from starting if the device detects THC at certain levels, they said.