E-Cigarette Use: Device Market, Study Design, and Emerging Evidence of Biological Consequences

Abstract

Electronic cigarettes are frequently viewed as a safer alternative to conventional cigarettes; however, evidence to support this perspective has not materialized. Indeed, the current literature reports that electronic cigarette use is associated with both acute lung injury and subclinical dysfunction to the lung and vasculature that may result in pathology following chronic use. E-cigarettes can alter vascular dynamics, polarize innate immune populations towards a proinflammatory state, compromise barrier function in the pulmonary endothelium and epithelium, and promote pre-oncogenic phenomena. This review will summarize the variety of e-cigarette products available to users, discuss current challenges in e-cigarette study design, outline the range of pathologies occurring in cases of e-cigarette associated acute lung injury, highlight disease supporting tissue- and cellular-level changes resulting from e-cigarette exposure, and briefly examine how these changes may promote tumorigenesis. Continued research of the mechanisms by which e-cigarettes induce pathology benefit users and clinicians by resulting in increased regulation of vaping devices, informing treatments for emerging diseases e-cigarettes produce, and increasing public awareness to reduce e-cigarette use and the onset of preventable disease.

The role of synthetic coolants, WS-3 and WS-23, in modulating E-cigarette-induced reactive oxygen species (ROS) in lung epithelial cells

“…Concerning the findings of other studies investigating the physiological effects of using coolant containing e-liquids, using human bronchial epithelial cell cultures, previously, another study found that treatment with menthol significantly increased mitochondrial ROS via the TRPM8 receptor [30] . BEAS-2B cell exposures reported by these investigators consisted of aerosol treatments, in which cells were exposed for two separate 1.5-minute durations, separated by an incubation period; however, our cell treatment protocol conducted cell culture exposures through direct stimulation (e-liquid being directly pipetted into cell-culture media) as reported recently [31] , [32] .…”

“…However, n contrast to Omaiye et al [33] , which assessed the cytotoxicity induced by different treatments, our study assessed differences in ROS production. Additionally Omaiye et al [33] used aerosol exposures, whereas our study conducted cell-culture exposures via direct stimulation [32] . We further determined the cytotoxicity of the cooling agents, when WS-23 was treated to BEAS2B cells for hazard characterization.…”

“…Epithelial cells lining the airways are the first structural cell targets of any inhaled substances [36] and, the inhalation of e-cigs results in pulmonary epithelial cells being exposed to aerosols generated from e-liquids. In comparison to aerosol exposures, e-cig cell exposures using direct stimulation allows for a more precise control of dosage and a more expeditious analysis of different types of e-liquids consisting of various flavors, nicotine concentrations, and coolant concentrations [32] . However, cell cultures conducted with e-liquids via direct stimulation do not emulate the process associated with the actual usage of e-cigs which is the inhalation of aerosolized e-liquids into the lungs (“vaping”).…”

A Review of Electronic Cigarettes and Liquid Nicotine Poisoning Exposure Cases in the United States

“…The limitation of data for e-cigarette acute exposure is mainly due to the vast variety of commercially available e-cigarette device designs, pattern of use, and variability in the commercially available aerosolized solutions. (73). According to a survey querying e-cigarette users, consumers perceive the e-cigarettes as a safe and cheaper alternative to quitting smoking and helping in withdrawal symptoms during quitting of smoking (74,75).…”

Considerations on dosimetry for in vitro assessment of e-cigarette toxicity

“…Indeed, users can choose between various coil types (vertical, dual, triple, multiple, twisted, mesh, etc. ), made of different alloys containing iron, chromium, aluminum or nickel and coils can be wicked with several materials including organic cotton balls, silica fibers wick, or Stainless Steel Mesh among others [ 10 ]. Moreover, a wide range of resistances is available on the market with values typically ranging from 0.1 to 3 ohms allowing the vaper to modify the density and temperature of the aerosol created.…”