As the marijuana legalization discussion continues to cultivate strong support in poll after poll – the never-ending debate rages on – how high is too high to drive? With just north of 40% of the states in the US having medical marijuana laws, this is the chronic question which many have been trying to answer. Colorado and Washington State have both tried to address this issue in a scientific manner…and failed miserably. Thanks to a recently released report in Clinical Chemistry – a peer-reviewed medical journal – that might be about to change… Or not?
There’s new research suggesting that a cannabis-based breath test may be the most accurate method for police to test and assess motorists for THC in their blood. Similar to the much dreaded “breathalyzer” test utilized on suspected drunk drivers as a means of determining their blood alcohol content.
The methodology deployed for this study was simple, the researchers collected exhaled breath samples from both chronic marijuana users (smokes pot more than four times a week) and the weekend pot smoker (smokes weed less than two times per week) after consuming marijuana that contained a measured 6.8% of THC.
What the researchers found may be a game changer. THC, the primary desired psychoactive cannabinoid thought to be responsible for marijuana’s “high” feeling – and generally considered to be the culprit in diminished driving skills, was discovered to be the primary cannabinoid found in the new breathalyzer samples. Most surprisingly, TCH-COOH a byproduct marijuana metabolite of THC was discovered when they blew these tests. There was however one sample which was found to contain the CBN cannabinoid – and oxidative degradation product of THC which is thought to have some minor psychoactive properties, though substantially less potent than straight THC.
Results: THC was the major cannabinoid in breath; no sample contained THCCOOH and only 1 contained CBN. Among chronic smokers (n = 13), all breath samples were positive for THC at 0.89 h, 76.9% at 1.38 h, and 53.8% at 2.38 h, and only 1 sample was positive at 4.2 h after smoking. Among occasional smokers (n = 11), 90.9% of breath samples were THC-positive at 0.95 h and 63.6% at 1.49 h. One occasional smoker had no detectable THC. Analyte recovery from breath pads by methanolic extraction was 84.2%–97.4%. Limits of quantification were 50 pg/pad for THC and CBN and 100 pg/pad for THCCOOH. Solid-phase extraction efficiency was 46.6%–52.1% (THC) and 76.3%–83.8% (THCCOOH, CBN). Matrix effects were −34.6% to 12.3%. Cannabinoids fortified onto breath pads were stable (≤18.2% concentration change) for 8 h at room temperature and −20°C storage for 6 months.
Conclusions: Breath may offer an alternative matrix for testing for recent driving under the influence of cannabis, but is limited to a short detection window (0.5–2 h).
While this report offers fodder for discussion, it seems somewhat lacking in its ability to answer the burning question at the back of every stoners mine, “If I smoked weed seven days ago… Will I still test positive for THC now, while stoned cold sober?!” As recently occurred in one study, where 6 of 25 participants who had smoked weed seven days prior to testing – still tested positive for active levels of THC.