Baltimore, MD: The psychoactive cannabinoid THC may be present in the breath of subjects who recently inhaled marijuana, according to clinical trial data published online in the journal Clinical Chemistry.
Investigators at the National Institutes of Health in Baltimore, Maryland and the Karolinska University Hospital in Stockholm, Sweden analyzed the exhaled breath of occasional and habitual marijuana consumers shortly after subjects inhaled a standardized cannabis cigarette of 6.8 percent THC. Researchers sought to identify whether THC, its primary metabolite THC-COOH, or cannabinol (CBN), a non-psychoactive cannabinoid, were present in breath at detectable levels following smoking.
Researchers reported identifying the presence of THC in both occasional and in regular consumers for limited periods of time following subjects’ inhalation of marijuana. Authors concluded: "Among chronic smokers (n = 13), all breath samples were positive for THC at 0.89 hours, 76.9 percent at 1.38 hours, and 53.8 percent at 2.38 hours, and only one sample was positive at 4.2 hours after smoking. Among occasional smokers (n = 11), 90.9 percent of breath samples were THC-positive at 0.95 hours and 63.6 percent at 1.49 hours. One occasional smoker had no detectable THC."
No samples tested positive for the presence of the carboxy THC metabolite and only one subject tested positive for the presence of CBN.
Authors concluded that breath analysis potentially offers an alternative matrix for identifying subjects who had recently inhaled cannabis. The study did not attempt to correlate the detection of THC in breath with actual behavioral impairment of any kind.
Swedish researchers had previously reported in April that breath analysis is sensitive to the presence of THC in those who have recently consumed cannabis as well as other controlled substances. That study reported that 89 percent of subjects tested positive for THC in breath. Investigators reported that the results "confirmed the potential of exhaled breath as an alternative specimen for toxicological investigations."
For more information, please contact Paul Armentano, NORML Deputy Director, at: firstname.lastname@example.org. Full text of the study, "Cannabinoids in exhaled breath following controlled administration of smoked cannabis," appears in Clinical Chemistry.