The intoxicating cannabinoid tetrahydrocannabinol (THC) can be detected in breath after smoking cannabis, but what about after eating edibles? It appears it can.
Researchers from the USA’s National Institute of Standards and Technology (NIST) and their partners at University of Colorado Anschutz say they have made the first measurement of THC in breath from edible cannabis.
The study involved 29 participants who each brought a cannabis gummy to the lab with them containing anything from 5 to 100 milligrams of THC. A breath sample from the participants was taken before ingestion, then approximately every hour afterwards for three hours.
While participants were asked to abstain from cannabis for eight hours before the study, the researchers detected THC in most of the participants before they consumed the edible, again illustrating that THC can be detected long after consumption — days or even weeks in some cases.
Regardless, the researchers found:
- 19 of the participants showed significant increases in THC in the three-hour period after ingesting the edible.
- 4 of the participants did not show any change in THC.
- 6 showed only a decrease from their first breath sample.
With regard to the last result, the researchers stated measurements may have possibly missed the time window in which a spike in THC could have occurred.
While the study indicates multiple breath measurements over a period of time could be a way to use a breathalyzer to detect cannabis use no matter how it’s ingested, devices will still need appropriate standards in place to ensure they are accurate and used correctly said Tara Lovestead, a NIST chemical engineer involved with the research.
“This proof-of-concept study shows that THC concentration in breath can increase after the ingestion of cannabis-infused edibles, but the uncertainty of breath measurements and a longer time window need to be further explored,” states the study abstract.
But that still doesn’t get around the issue of a THC detection long after any impairment may occur.
NIST has previously published research demonstrating the difficulties of using breath measurements to distinguish between a person who uses cannabis regularly but hasn’t done so recently, and someone who has.
The new research has been published in the Journal of Analytical Toxicology.
