Prevalence and Stability of THC in Baseline Breath Samples Collected after Overnight Abstinence from Cannabis Use

Breath is a promising non-invasive matrix for roadside detection of recent cannabis use, and peer-reviewed studies have demonstrated that THC (delta-9-tetrahydrocannabinol) concentrations in breath increase immediately following cannabis use. However, cannabis breathalyzer science must address individual variability, indicated by order-of-magnitude variations in THC concentrations within previous studies, and the concern that regular cannabis users may have THC in their breath even after periods of non-use. We hypothesize that THC rate of change, determined by collecting breath samples at two timepoints, can determine recent cannabis use. This presentation will describe the ongoing Breath Measurements of Acute Cannabis Elimination (BACE) study and will focus on the prevalence and stability of THC in baseline breath samples. BACE study participants are near-daily cannabis users who provide samples following an overnight (eight hour) period of abstinence from cannabis use on three occasions: one clinical session and two study sessions that occur in a mobile laboratory. Three breath samples with spirometry information on volume and flow rate are collected at the clinical session. Ten additional samples at controlled timepoints after cannabis use are collected over two hours at the mobile laboratory session. THC and other cannabinoids are identified and quantified with liquid chromatography-tandem mass spectrometry. While this is an on-going study, the analysis of the baseline samples from the first participants show that THC can be detected in breath long after cannabis use. Cannabis breathalyzer strategies will therefore require novel protocols beyond the single timepoint measurement that is typical for an alcohol breathalyzer. This presentation will discuss potential two timepoint measurement scenarios and the consistency of breath samples as determined by spirometry data.