Toxicant Exposure and Cardiovascular Effects: Cannabis vs Tobacco


  1. Gideon St Helen, PhD
Research Fields: 
Tobacco Effects

Proposition 64 legalized adult recreational use of cannabis in California, and there are concerns it will lead to an increase in prevalence and intensity of cannabis use in the state. Further, electronic vaporizers, which heat but do not combust cannabis materials, are being introduced in the market for use with cannabis. Vaporizers are perceived as safer alternatives to smoking and are gaining popularity. Despite growing favorable public opinion of cannabis in its various forms, and pervasive and increasing intensity of use, we do not fully understand its inherent health consequences, including cardiovascular disease risks, or its risks relative to that of tobacco cigarettes, which have been extensively studied. To fill these data gaps, we are conducting a study with an overall goal to examine the cardiovascular disease risk of combusted and vaped dry herb cannabis in comparison to tobacco cigarettes. The central hypothesis is that the cardiovascular disease risk of cannabis smoking is comparable to that of tobacco smoking, and while vaping cannabis elevates cardiovascular disease risks, the risks are lower than that of smoking cannabis.

We are enrolling 18 experienced dual cannabis-tobacco smokers in a 3-arm crossover study. These arms include their usual smoked cannabis, vaped cannabis (PAX dry herb vaporizer), and their usual brand of tobacco cigarette. During each arm, they are admitted to a hospital research ward for two days. On the first day, they participate in two sessions, a standardized puffing session and a 2-hr session of ad libitum access to the assigned product, separated by 6 hours of abstinence between these sessions. We assess changes in intake of nicotine or tetrahydrocannabinol (THC), physiologic, and subjective effects, such as reward, craving reduction, and satisfaction. On the second day, they have ad libitum access to the assigned product from 8:00 AM to midnight, and markers of cardiovascular effect biomarkers, nicotine, and THC are measured in blood, and 24-hour urine is collected for measurement of biomarkers of toxicant exposure and cardiovascular effects. An abstinence day is added after the second day of the last block to assess exposure and effects biomarkers during a period of abstinence from cannabis (smoked/vaped) or tobacco.