Electronic nicotine delivery system design and aerosol toxicants: A systematic review

• Published in: PloS one 2020-06, Vol.15 (6), p.e0234189
• Main Authors: Ward, Alexandra M, Yaman, Rola, Ebbert, Jon O
• Format: Article
• Language: English
• Subjects: Aerosol concentrations; Aerosols; Aromatic hydrocarbons; Batteries; Carbonyl compounds; Carbonyls; Chemicals; Cigarettes; Constituents; Contaminants; Contamination; Design; Design and construction; Electronic cigarettes; Flavorings; Free radicals; Health risks; Heating; Heating equipment; Hydrocarbons; Independent regulatory commissions; Metals; Nicotine; Nitrosamines; Nitrosoamines; Organic chemistry; Oxygen; Physical Sciences; Polycyclic aromatic hydrocarbons; Power (Philosophy); Reactive oxygen species; Regulatory agencies; Research and Analysis Methods; Reviews; Risk reduction; Smoking; Systematic review; Systems design; Thermal degradation; Tobacco; Toxic substances; Toxicants; Trace elements; VOCs; Volatile organic compounds
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0234189

Background Electronic nicotine delivery systems (ENDS; e-cigarettes), consisting of a battery, heating element and e-liquid, have evolved significantly with wide variation in design, components, operating powers, and chemical constituents. Generated aerosols have been reported to contain potentially toxic substances. We conducted a systematic review to assess what is known about the presence of toxicants in ENDS aerosols in order to inform how system design could mitigate risk. Methods Articles reporting on or evaluating design characteristics of ENDS and aerosol constituents were included and summarized. Results The search identified 2,305 articles, of which 92 were included after full-text review. Findings were grouped into 6 major categories of potentially harmful chemicals: carbonyls, volatile organic chemicals, trace elements, reactive oxygen species and free radicals, polycyclic aromatic hydrocarbons, and tobacco-specific nitrosamines. In general, higher concentrations of aerosol toxicants are associated with increased power or voltage. Aerosol toxicants are also associated with e-liquid flavoring agents existing as primary ingredients or as products of thermal degradation. Conclusions Improved ENDS design can reduce toxicant levels. Additional research is needed to develop a framework for optimizing system characteristics to minimize exposure, especially with respect to heating power and e-liquids. Both manufacturers and regulatory agencies have roles in reducing toxicants and potential health risks from ENDS.