Toxicology of flavoring- and cannabis-containing e-liquids used in electronic delivery systems.

The toxicity of flavored e-liquids and flavorings has been studied in 67 publications, with a focus on the respiratory tract.
* aerosolized flavorings in e-liquids are not fully metabolized in the lung and a portion of the inhaled dose is absorbed into the bloodstream and distributed throughout the body.
* Sixty-five flavorings used in e-liquids have been shown to induce toxicity, with cinnamaldehyde being the most frequently reported to be cytotoxic.
* Linalool is one of the chemicals listed in Table 1 as being cytotoxic.
* a specific flavoring or flavored e-liquid has not been identified as having an impact on nicotine uptake.
* In an in vivo study, male C57BL6/J mice exposed to aerosolized Magnificent Menthol flavored e-liquid had significantly higher urinary excretion of the acrolein metabolite 3-hydroxypropyl mercapturic acid and nicotine alkaloids compared with mice exposed to Classic Tobacco flavored e-liquid.

Therefore, it can be summarized that the study of the toxicity of flavored e-liquids and flavorings has shown that aerosolized flavorings are not fully metabolized in the lung and can be absorbed into the bloodstream. Cinnamaldehyde is the most frequently reported chemical to be cytotoxic, and linalool is one of the chemicals listed to induce toxicity. a specific flavoring or flavored e-liquid has not been identified to have an impact on nicotine uptake. In an in vivo study, male mice exposed to Magnificent Menthol flavored e-liquid had higher levels of urinary excretion of the acrolein metabolite and nicotine alkaloids compared with mice exposed to Classic Tobacco flavored e-liquid.

Stefaniak aB, LeBouf RF, Ranpara aC, Leonard SS. Toxicology of flavoring- and cannabis-containing e-liquids used in electronic delivery systems. Pharmacology & therapeutics. 2021;224:107838. doi:10.1016/j.pharmthera.2021.107838