Comprehensive overview of common e-liquid ingredients and how they can be used to predict an e-liquid’s flavour category

Introduction:
This article provides an overview of the ingredients and flavors commonly found in e-cigarette liquids (e-liquids) and how this information can be used to predict an e-liquid's flavor category. The study used a dataset of 16,839 e-liquids and identified the most frequently used ingredients and their median quantities. a random forest algorithm was then used to predict e-liquids' flavor categories based on their ingredients.

Key Points:

* The study identified 219 unique ingredients, of which 213 were flavorings, present in more than 100 e-liquids.
* The mean number of flavorings per e-liquid is 10±15.
* The most frequently used flavorings are vanillin (present in 35% of all liquids), ethyl maltol (32%), and ethyl butyrate (28%).
* Twenty-nine category-specific flavorings were identified, with β-damascone for tobacco, eucalyptol, menthone, and peppermint oil for menthol/mint, and ethyl heptanoate, ethyl nonanoate, isoamyl alcohol, and lactic acid for alcohol.
* E-liquids' flavor categories were predicted with an overall accuracy of 70%.
* The RF model assigned 56% of the unclassifiable e-liquids to the tobacco category, 10% to fruit-other, 9% to fruit-berries, and 7% to dessert.
* When only using information about the presence of ingredients (a qualitative approach), the RF algorithm had an overall prediction accuracy of 66%.

Main Message:
The study demonstrates that information from manufacturers can be used to identify frequently used and category-specific flavorings in e-liquids. additionally, qualitative and quantitative ingredient information can be used to successfully predict an e-liquid's flavor category. This approach can serve as an example for regulators who have similar datasets available to support compliance and control of potential future regulations of e-liquid flavors.

Krüsemann, Erna J Z, anne havermans, Jeroen L a Pennings, Kees De Graaf, Sanne Boesveldt, and Reinskje Talhout. “Comprehensive Overview of Common E-Liquid Ingredients and how They Can Be Used to Predict an e-Liquid’s Flavour Category.” Tobacco Control 30, no. 2 (March 2021): 185–91. https://doi.org/10.1136/tobaccocontrol-2019-055447.