Chemical evaluation of electronic cigarettes

Introduction:
This text is a summary of existing research findings related to the chemical composition of electronic cigarettes (e-cigarettes), highlighting the limitations and information gaps that are critical for reliable chemistry data collection necessary for e-cigarette hazard evaluation. The summary is based on a systematic literature search conducted through September 2013, which yielded 36 articles, of which 29 were deemed relevant for analysis. The study design and major points are outlined below.

Key points:

* E-cigarettes are nicotine delivery devices that simulate cigarette smoke by generating an aerosol from liquid containing nicotine and flavorings.
* The levels of nicotine, tobacco-specific nitrosamines (TSNas), aldehydes, metals, volatile organic compounds (VOCs), flavors, solvent carriers, and tobacco alkaloids in e-cigarette refill solutions, cartridges, aerosols, and environmental emissions vary considerably.
* The delivery of nicotine and the release of TSNas, aldehydes, and metals are not consistent across products, and the nicotine level listed on the labels of e-cigarette cartridges and refill solutions is often significantly different from measured values.
* Phenolic compounds, polycyclic aromatic hydrocarbons, and drugs have also been reported in e-cigarette refill solutions, cartridges, and aerosols.
* Varying results in particle size distributions of particulate matter emissions from e-cigarettes across studies have been observed.
* Methods applied for the generation and chemical analyses of aerosols differ across studies.
* Performance characteristics of e-cigarette devices also vary across and within brands.

Main message:

The text highlights the need for additional studies based on knowledge of e-cigarette user behaviors and scientifically validated aerosol generation and chemical analysis methods to generate reliable measures of chemical quantities. This would allow comparisons of e-cigarette aerosol and traditional smoke constituent levels and inform an evaluation of the toxicity potential of e-cigarettes. The text also emphasizes the importance of e-cigarette manufacturers providing complete information on the chemicals used in the manufacturing process and the chemicals that may be released or synthesized during the aerosol generation process. Safety concerns exist regarding e-cigarette users' exposure to harmful and potentially harmful constituents (hPhCs), including nicotine, which has the potential to cause addiction and other adverse events.

Cheng, Tianrong. “Chemical Evaluation of Electronic Cigarettes.” Tobacco Control 23, no. suppl 2 (May 2014): ii11–17. https://doi.org/10.1136/tobaccocontrol-2013-051482.