Comparison of Systemic Exposure to Toxic and/or Carcinogenic Volatile Organic Compounds (VOC) during Vaping, Smoking, and Abstention

vaping or cigarette-only use, and 2 days of enforced abstention. Concentrations of VOC metabolites were higher during smoking compared with vaping, except for the methylating agents' metabolite. The fold-difference in concentrations when smoking relative to vaping ranged from 1.31 (1.06-1.61; geometric mean, 95% confidence interval; 1,3-butadiene) to 7.09 (5.88-8.54; acrylonitrile). Metabolites of acrylamide [fold difference of 1.21 (1.03-1.43)] and benzene [1.46 (1.13-1.90)] were higher during vaping compared with abstention. The 1,3-butadiene and propylene oxide metabolites were higher in variable-power tank users compared with users of cig-a-likes. E-cigarettes expose users to lower levels of toxic VOCs compared with cigarette smoking, supporting their harm reduction potential among smokers. However, some e-cigarettes expose users to VOCs such as acrylamide, benzene, and propylene oxide, and may pose health risks to nonsmoking users. The results of our study will inform regulators in assessing e-cigarettes with respect to the balance between its potential harm reduction for adult smokers and risk to nonsmoking users.