Reliable roadside or workplace breath testing for marijuana use might not be far off, indicates a group of National Institute on Drug Abuse (NIDA) researchers, but the detection window in testing could be fairly short.
In an article published in September in the journal Clinical Chemistry, the NIDA scientists reported on results of a study that collected exhaled breath from two dozen chronic or occasional marijuana smokers for purposes of measuring levels of THC and other cannabinoids. THC, the main psychoactive chemical in marijuana, was the major cannabinoid detectable in the breath analysis.
Among 13 chronic marijuana smokers (defined as smoking at least four times per week), all breath samples were positive for THC at 0.89 hours. The percentage of positives was 76.9% at 1.38 hours and 53.8% at 2.38 hours, with only one positive detected at 4.2 hours. A somewhat similar pattern was seen for 11 occasional smokers tested (those who smoked less than twice a week).
The researchers stated in the study abstract, “Breath may offer an alternative matrix for testing for recent driving under the influence of cannabis, but is limited to a short detection window (0.5 to 2 hours).”