Safety of vaped cannabis: Pharmacokinetic differences between cannabis smoking and liquid vaping

Growing evidence suggests that cannabis use is associated with adverse mental health outcomes, including impaired cognition during acute exposure. New methods of consuming cannabis, such as vaping, are more readily available with legalization, yet recent outbreaks of respiratory illness associated with consumption of mostly unregulated THC-containing vaping products has called into question the safety of this mode of administration. This study evaluated the effects of vaping cannabis relative to smoked dried cannabis, with a primary focus on the acute cognitive impairment that may underlie risk for mental health harms. We also compared the physiological, pulmonary and toxicity effects of smoked cannabis and vaped cannabis. Eligible participants were invited to the lab and were permitted to smoke or vape their usual cannabis using their usual methods. Cognitive measures were taken before smoking/vaping cannabis and at two time points after. Pulmonary function were also measured and emissions in the air were evaluated. This study provided valuable insights into the relative safety of different routes of cannabis administration and provide evidence-based data on the safety of vaping cannabis.

This study was novel in that we studied the impact of ecologically valid doses of cannabis on cognition and related measures. Canada is in a unique position to be able to study commercialized cannabis in the lab. In this study we compared the effects of a user’s preferred smoked or vaped cannabis on cognition, pulmonary function and air emissions. We found that cannabis had an impact on cognitive measures using the CANTAB battery of tests; this provides one of the first uses of CANTAB for studying cannabis. Further, we found that pulmonary function was impaired in cannabis users, suggesting that the use of cannabis has health consequences. Air emissions contained higher levels of THC after smoked cannabis as compared to vaped cannabis.

This study led to several follow-up projects. In one, we are conducting a systematic review summarized published studies comparing the effects of different routes of administration of cannabis use on cognitive function and blood THC. Further, the preliminary cognitive and air emissions data allowed to us to prepare several grant submissions. This study is highly novel in its inter-disciplinary nature.

This study is funded by the EMHSeed opportunity (University of Toronto and CAMH)