Abstract View
Electronic Cigarette: The Knowns, Known Unknowns, and Unknown Unknowns
YIFANG ZHU, University of California, Los Angeles
Abstract Number: 491
Working Group: Invited by Conference Chair
Abstract
Electronic cigarettes (E-cigs) are battery-operated devices gaining increasing popularity as an alternative to tobacco cigarettes. The global e-cig market is projected to reach $48.9 billion by 2025, with more than 70% of the market in North America and Europe. The number of e-cig users has also increased markedly, especially among adolescents. Yet, little is known regarding the physiochemical characteristics or health-related effects for the large array of aerosols that are inhaled and exhaled by e-cig users. With the rapid increase in e-cig users worldwide, secondhand exposure to e-cig aerosols has also become a serious public health concern. Through a series of studies, we have systematically characterized mainstream and secondhand e-cig aerosols in chambers, in laboratory indoor environments, and in vape shops. We found that e-cig device voltage, puff duration, puff volume, and e-liquid ingredients are important factors determining physiochemical properties of e-cig aerosols. We also summarize the evidence on the effects of e-cigs on indoor air quality, chemical compositions of mainstream and secondhand e-cig aerosols, and associated respiratory and cardiovascular effects. The use of e-cigs in indoor environments leads to high levels of fine and ultrafine particles similar to tobacco cigarettes. Concentrations of chemical compounds in e-cig aerosols are generally lower than those in tobacco smoke, but a substantial amount of vaporized propylene glycol, vegetable glycerin, nicotine, and toxic substances, such as aldehydes and heavy metals, have been reported. Exposures to mainstream e-cig aerosols have biologic effects, but only limited evidence showing adverse respiratory and cardiovascular effects in humans. Long-term studies are needed to better understand the dosimetry and health effects of exposures to secondhand e-cig aerosols. Future studies also need to focus on identifying vulnerable populations and monitor places that may contribute to high levels of secondhand exposures.