The Toxicological Effects of e‐Cigarette Use in the Upper Airway: A Scoping Review.

Objective: While evidence continues to emerge on the negative health effects of electronic cigarettes (e‐cigarettes) on the lungs, little is known regarding their deleterious effects on the upper airway. The purpose of this review is to summarize the toxicological effects of e‐cigarettes, and their components, on the upper airway. Data Sources: PubMed, SCOPUS, EMBASE databases. Review Methods: Systematic searches were performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta‐analyses guidelines from 2003 to 2023. Studies were included if they investigated the toxicological effects of e‐cigarette exposure on human or animal upper airway tissue. Two authors independently screened, reviewed, and appraised all included articles. Results: A total of 822 unique articles were identified, of which 53 met inclusion criteria and spanned subsites including the oral cavity (22/53 studies), nasal cavity/nasopharynx (13/53), multiple sites (10/53), larynx (5/53), trachea (2/53), and oropharynx (1/53). The most commonly observed consequences of e‐cigarette use on the upper airway included: proinflammatory (15/53 studies), histological (13/53), cytotoxicity (11/53), genotoxicity (11/53), and procarcinogenic (6/53). E‐cigarette humectants independently induced toxicity at multiple upper airway subsites, however, effects were generally amplified when flavoring(s) and/or nicotine were added. Across almost all studies, exposure to cigarette smoke exhibited increased toxicity in the upper airway compared with exposure to e‐cigarette vapor. Conclusion: Current data suggest that while e‐cigarettes are generally less harmful than traditional cigarettes, they possess a distinct toxicological profile that is enhanced upon the addition of flavoring(s) and/or nicotine. Future investigations into underexamined subsites, such as the oropharynx and hypopharynx, are needed to comprehensively understand the effects of e‐cigarettes on the upper airway. [ABSTRACT FROM AUTHOR]