Emerging ENDS products and challenges in tobacco control toxicity research

Abstract

Electronic nicotine delivery systems (ENDS) continue to rapidly evolve. Current products pose unique challenges and opportunities for researchers and regulators. This commentary aims to highlight research gaps, particularly in toxicity research, and provide guidance on priority research questions for the tobacco regulatory community. Disposable flavoured ENDS have become the most popular device class among youth and may contain higher nicotine levels than JUUL devices. They also exhibit enhanced harmful and potentially harmful constituents production, contain elevated levels of synthetic coolants and pose environmental concerns. Synthetic nicotine and flavour capsules are innovations that have recently enabled the circumvention of Food and Drug Administration oversight. Coil-less ENDS offer the promise of delivering fewer toxicants due to the absence of heating coils, but initial studies show that these products exhibit similar toxicological profiles compared with JUULs. Each of these topic areas requires further research to understand and mitigate their impact on human health, especially their risks to young users.

Sex Differences in Oxidative Stress–Mediated Reductions in Microvascular Endothelial Function in Young Adult e-Cigarette Users

“…The diversity of EC devices, chemical additives, nicotine concentrations, and chemical forms, and use patterns among individuals make it virtually impossible to discern what specific components of EC use lead to alterations in vascular function. 35 Within our cohort, EC users frequently reported using >1 flavor and brand of e-liquid and device. Subanalyses of flavoring, EC device, and frequency of use did not correlate with our measures of endothelium- or NO-dependent dilation.…”

Aerosolized nicotine from e-cigarettes alters gene expression, increases lung protein permeability, and impairs viral clearance in murine influenza infection

“…Moreover, a significant proportion of e-cigarette users, particularly youth and young adults, did not smoke cigarettes previously ( 114 , 115 ). These results add to the body of evidence that nicotine is harmful even in e-cigarettes and should inform the regulation of nicotine-containing products given that the amount of nicotine in popular e-cigarette products has increased over time ( 12 ) and countries are beginning to implement limits on nicotine content ( 116 ).…”

“…Additionally, the mice were inoculated with a relatively moderate dose of influenza virus and, thus, the influence of e-cigarette exposure on mortality from infection could not be assessed. Nonetheless, these limitations indicate that further studies are necessary to understand the risks associated with e-cigarettes in a rapidly evolving commercial landscape, particularly as synthetic nicotine is introduced into the marketplace ( 12 ).…”

“…Nicotine is an addictive stimulant found in cigarette smoke that can also be inhaled via electronic nicotine delivery systems, or e-cigarettes. These devices use a heated metal coil to aerosolize nicotine solubilized in an e-liquid mixture of vegetable glycerin (VG) and propylene glycol (PG) as well as other additives like flavoring compounds ( 12 , 13 ). Studies have shown that exposure to e-cigarette aerosols has injurious effects in the respiratory system linked to different chemicals in these products ( 14 ).…”

Chemical and physiological interactions between e-liquid constituents: cause for concern?

“…1 However, a wide variety of specific sampling and analytical techniques have been developed for ENDS research 1 to address the challenging complexity and dynamics of the ENDS product landscape. 8 ENDS risk assessments for regulatory purposes largely rely on assessments of individual chemicals or of composite commercial mixtures of e-liquids and/or their corresponding aerosols. There is a significant knowledge gap concerning the health risks from the combined exposure to multiple chemicals from ENDS usage.…”