Weed DUI tests have been shrouded in controversy for a while now, with many claiming that they’re rooted in pseudoscience. While alcohol can be objectively tested for using tools like breathalyzers, weed tests often consist of assessments of coordination, muscle tone, and pupil size. According to scientists like William McNichol, these tests aren’t rooted in science and are too subjective to be taken seriously.
As law enforcement cracks down on the action, it’s important that weed users are protected from false accusations of driving high and that roads are kept safe. This may be possible soon: researchers at the National Institute of Standards and Technology (NIST) claim to have made the first breath detection of THC following the consumption of edibles.
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In the study conducted by three NIST researchers and one from the University of Colorado Anschultz Medical, 29 people’s breath samples were collected before and after consuming a THC-infused edible. The edibles ranged in strength from five to 100mg of THC—since the participants brought their own products, though, the amounts were not verified by the study.
The researchers used both an aerosol and a condensate device to take samples before ingestion and then at the 47, 92, and 180-minute marks. Participants were told to abstain from using edibles for 12 hours prior to the study and from smoking for eight hours, but 27 of the 29 samples were found to have contained THC before the point of ingestion. This detection of residual cannabis—ranging from trace amounts to greater than 0.4 ng/device— raises some issues that will have to be addressed in future iterations of the study.
“The finding of detectable and/or quantifiable THC before cannabis use shows how challenging it is to interpret a single THC concentration measurement in breath with no prior information about THC at baseline,” said the study’s authors.
After ingesting the edibles, 19 of the 29 participants’ breath showed a significant increase in THC, four showed no change, and 6 showed a significant decrease. Oddly enough, the ones whose tests showed decreases were the ones that had the highest concentrations in the pre-ingestion screens. The other results, on the other hand, support the claim that recent weed consumption can be detected by breath.
There were some discrepancies in the types of cannabinoids during the study. According to the researchers, “When detected, CBN and CBG matched THC trends, but there were multiple instances where CBD and THC disagreed, suggesting differences in biological processing or clearance.”
Because of its small sample size and inconclusive results, NIST’s study does not mean that the challenges of weed breath tests are solved. However, it does mean that multiple measurements over a period of time may detect recent cannabis use—eventually, this finding may lead to a proper breath testing system. NIST has clarified that it’s not intending to develop a testing device, but rather to ensure that any measurements used in the future will be accurate and reliable. The agency will host a workshop with device makers in September.
“Looking forward, we can now tackle the question of when THC increases after edible ingestion, when it goes back to baseline, and how to analyze breathalyzer data to get the information needed,” said Kavita Jeerage, one of the NIST researchers.
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As the stoned driving discourse continues, hopefully, NIST’s findings will ensure that both roads and stoners will be safe.