Composition of aerosols from thermal degradation of flavors used in ENDS and tobacco products.

Introduction:
This text provides an in-depth analysis of the aerosol generation system used to create high and low temperature atmospheres for heating four key flavorants commonly found in tobacco products. The study aims to characterize the composition of both the aerosol in the gas and particulate phase for each flavorant at different temperatures. The key points and main message of the text are summarized below.

Key Points:

* The aerosol generation system was evaluated for the efficiency of aerosol generation, which was found to be ~70% for all flavorants.
* Samples were collected using different methods to enable analysis of volatile organic compounds (VOCs), carbonyls, polycyclic aromatic hydrocarbons (Pahs), and polar compounds.
* The concentration of compounds in the flavorant atmosphere was determined by burning each flavoring liquid at high and low temperature.
* The composition of each individual flavorant degradant atmosphere at different temperatures varied, and was in general related to the chemical structures of the starting materials.
* Cinnamaldehyde showed degradation to primary aromatic compounds, with eugenol and benzoic acid/dibenzoic acid being the largest concentrations at low temperature and benzene at the high temperature.
* Eugenol is often used as a precursor of vanillin, and high temperature formed vanillin and benzene as well as low molecular weight VOCs.
* Menthol aromatizes and converts to benzoic and dibenzioc acid as the primary degradation products at both low and high temperatures.
* Vanillin degradation products at both temperatures included benzone and oxidized benzenes.

Main Message:
The study provides comprehensive data identifying chemicals that are formed solely from thermal degradation of commonly used flavors as well as quantifying the extent to which these chemicals are generated upon pyrolysis and/or oxidation of flavor chemicals. The study highlights the importance of evaluating the toxicological effects of aerosols derived from heated and burned flavors to assess whether these additives generate toxic thermal degradation products. The findings show that products of thermal degradation of common flavorant compounds vary by flavorant and by temperature and include a wide variety of harmful and potentially harmful constituents (hPhCs). Therefore, it is crucial to consider the potential health risks associated with the use of flavorings in tobacco products and electronic cigarettes.

Kuehl PJ, McDonald JD, Weber DT, Khlystov a, Nystoriak Ma, Conklin DJ. Composition of aerosols from thermal degradation of flavors used in ENDS and tobacco products. Inhalation toxicology. 2022;34(11-12):319-328. doi:10.1080/08958378.2022.2103602