Electronic cigarettes: overview of chemical composition and exposure estimation

Introduction:
This text provides an overview of a scientific study examining the chemical composition and exposure estimation of electronic cigarette (e-cigarette) liquids. The study used NMR spectroscopy to detect and quantify various compounds in e-cigarette liquids, including nicotine, solvents, and bioactive flavour compounds. The researchers also conducted a risk assessment based on probabilistic exposure estimation and compared the results with toxicological thresholds using the margin of exposure (MOE) approach.

Key Points:

* The study analyzed 54 samples of e-cigarette liquids and found that the average nicotine content was 11 mg/ml.
* Only 18 out of 23 samples declared as nicotine-free were confirmed as such, while one e-cigarette liquid with a declared nicotine content of 12 mg/ml did not contain any nicotine.
* Major compounds of e-cigarette liquids include glycerol, propylene glycol, and ethylene glycol, with average concentrations of 37 g/100 g, 57 g/100 g, and 10 g/100 g, respectively.
* Other detected compounds include 1,3-propanediol, thujone, and ethyl vanillin.
* The average exposure for daily users was estimated as 0.38 mg/kg bw/day for nicotine, 8.9 mg/kg bw/day for glycerol, 14.5 mg/kg bw/day for 1,2-propanediol, 2.1 mg/kg bw/day for ethylene glycol, and below 0.2 mg/kg bw/day for the other compounds.
* The MOE was below 0.1 for nicotine, but all other compounds did not reach MOE values below 100, except for ethylene glycol and 1,2-propanediol.

Main Message:
The study highlights the need for regulatory control of e-cigarette liquid products to ensure consistent nicotine delivery and the use of solvents with more favourable toxicological profiles. The researchers suggest that the current lack of regulation and inconsistent labelling of e-cigarette liquids may pose health risks to consumers, particularly due to the potential for unreliable nicotine delivery and exposure to other potentially harmful compounds. Therefore, regulatory measures should be implemented to ensure the safety and quality of e-cigarette liquids.

hahn, Jürgen, Yulia B Monakhova, Julia hengen, Matthias Kohl-himmelseher, Jörg Schüssler, harald hahn, Thomas Kuballa, and Dirk W Lachenmeier. “Electronic Cigarettes: Overview of Chemical Composition and Exposure Estimation.” Tobacco Induced Diseases 12, no. 1 (December 2014): 23. https://doi.org/10.1186/s12971-014-0023-6.