Cannabis Edibles Can Now Be Detected in Breath, Opening Door for Future Roadside Tests

For the first time, cannabis consumed through edibles has been scientifically detected in a person’s breath, potentially paving the way for new methods of roadside testing. According to the National Institute of Standards and Technology (NIST), researchers successfully measured the presence of tetrahydrocannabinol (THC) — the psychoactive compound in cannabis — in breath samples following the ingestion of cannabis-infused gummies.

Unlike alcohol, for which breathalyzers have long been a reliable tool to determine recent use and impairment, cannabis has posed a challenge for law enforcement. THC’s complex molecular structure and low volatility make it difficult to detect, especially in low concentrations typically found in breath. Adding to the complexity, regular cannabis users can retain detectable levels of THC in their systems for days or even weeks after use, making it difficult to determine recent consumption based on a single measurement.

The NIST study involved 29 participants at the University of Colorado Anschutz Medical Campus, each bringing their own THC-infused edible, ranging from 5 to 100 milligrams. Researchers took baseline breath samples, then monitored THC levels hourly over three hours. In most cases, THC levels rose and then declined, offering key insights into how the compound is processed and expelled through the lungs after oral ingestion. Some participants, however, did not show a clear spike, likely due to timing variations in absorption or metabolism.

This new data dispels the belief that breath-detectable THC comes only from smoke residue, confirming that ingested THC also reenters the lungs via the bloodstream and can be exhaled. While NIST itself is not developing breathalyzer devices, the findings offer a foundation for companies to build tools capable of detecting cannabis consumption regardless of delivery method. NIST will host a workshop in September with device developers to discuss setting measurement standards and improving accuracy.

This breakthrough may lead to more reliable roadside cannabis testing methods, helping law enforcement identify recent use and potentially impaired drivers. However, experts caution that detecting THC in breath doesn’t directly correlate to intoxication levels — a challenge researchers are still working to address through further studies.

Article by multiple contributors, based upon information from the National Institute of Standards and Technology press release

---