Researchers at the University of Colorado Boulder and the National Institutes of Standards and Technology (NIST) are attempting to address the issue of driving impaired with their “Cannavan,” a mobile pharmacology lab designed to study the effects of cannabis use in real time.
Unlike alcohol, where breath tests reliably measure blood alcohol concentration (BAC), cannabis impairment lacks a clear standard. THC, the psychoactive compound in marijuana, is exhaled in trace amounts, making detection akin to finding a “needle in a haystack,” according to NIST chemical engineer Tara Lovestead. THC also remains in the body for days or even weeks after last use, making methods of detecting impairment like blood tests entirely unreliable.
The research team, led by associate professor Cinnamon Bidwell, is recruiting 45 regular cannabis users to help establish protocols for measuring impairment. Participants will consume cannabis in their homes using products from a single dispensary, Native Roots, before returning to the Cannavan for a series of breath and intoxication tests. Over two hours, researchers will collect 13 breath samples per participant, totaling more than 1,200 samples for analysis.
Initial findings suggest single breath tests are unreliable for determining impairment, but a multi-breath approach could prove more effective. If THC levels drop significantly between two breath samples taken minutes apart, recent use—and potential impairment—might be inferred. Future studies could also pave the way for a cannabis equivalent to BAC, combining breath tests with other assessments.
“If there is a tool they can use to assure they aren’t putting anyone at risk, that would be hugely beneficial,” Bidwell said.
THC can remain in the body for days or even weeks after last use, making methods of detecting impairment like blood tests entirely unreliable.
