Δ9-Tetrahydrocannabinol concentrations in exhaled breath and physiological effects following cannabis intake - A pilot study using illicit cannabis

Objectives: Delta(9)-Tetrahydrocannabinol (THC) can be measured in exhaled breath by using an aerosol particle collection device. The sampling procedure is simple, non-invasive and takes only 2-3 min. In the present study we measured the amount of THC in exhaled breath of cannabis users at specific time intervals up to 3 h after smoking one cannabis cigarette. Design and methods: The breath concentration-effect relationship was studied by measuring the pulse rate and the pupil diameter to assess physiological changes. THC and the main metabolite 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol were analyzed in exhaled breath by a liquid chromatography-tandem mass spectrometry method. Thirteen subjects (9 males and 4 females, aged 23-24 years) participated. Five of those were using cannabis more frequently than monthly. Results: THC was detected in most subjects already at baseline, concentrations increased following smoking and remained detectable for over 3 h (mean THC concentration in breath at 3 h: 1479 pg/sample). Pulse rate (p = 0.015) and pupil diameter (p = 0.044) were significantly altered up to 30 min after smoking. The detection window of cannabis in breath after smoking one cannabis cigarette in occasional and chronic smokers was at least 3 h. Only THC was detected, and not the metabolite. The THC concentration in exhaled breath was related to the physiological changes that occur over time. Conclusions: Exhaled breath can be used to detect recent cannabis exposure. (C) 2016 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.