A new study shows evidence that the flavorings used in e-cigarettes and other vaping products bring on acute inhalation toxicity, and some flavorings are more toxic than others.
According to the study, which was published online in the BMJ journal Tobacco Control, strawberry flavoring is the most toxic to cells in the airways. Higher battery voltage in the device was also associated with higher toxicity, MedPageToday reports.
Researchers from Roswell Park Cancer Institute in Buffalo, New York, found that menthol, coffee, and strawberry e-cigarette flavors all showed significant impact on overall toxicity. Piña colada and tobacco flavorings had less impact. The researchers did not study the chemical compounds that made up the flavorings, according to MedPageToday.
Dr. Maciej L. Goniewicz, Ph.D., PharmD, and his colleagues wrote, “Our data indicate that combinations of product, voltages, and flavorings exist that are cytotoxic to airway epithelial cells.” The study focused on the “acute effects of flavored electronic nicotine delivery systems (ENDS) products.” The researchers said their observations require need to be verified by testing the kinds of chronic exposure seen with regular use of vaping products.
The researchers bought six types of e-cigarettes from gas stations, convenience stores, vape shops, in Buffalo and in Daly City, California, and online. They purchased the nicotine liquids in five flavors (tobacco, piña colada, menthol, coffee, and strawberry) from a vape shop in Buffalo.
The researchers exposed H292 human bronchial epithelial cells to 55 puffs of freshly generated aerosol from an e-cigarette, tobacco smoke, or air (controls) and then they assessed the results. Among their main findings:
- Exposure to vapor from the e-cigarette devices resulted in decreased metabolic activity and cell viability and increased release of interleukin (IL)-1β, IL-6, IL-10, CXCL1, CXCL2, and CXCL10 compared with air controls;
- Conventional cigarettes had a greater adverse impact on cell viability and activity than most of the e-cigarettes tested;
- The battery voltage and the flavors significantly affected the toxicity of the vapor, of with a strawberry-flavored liquid producing the greatest toxicity
Interleukin compounds regulate immune responses.
The researchers used flavoring liquids with different nicotine concentrations but the found no significant differences between the concentrations and the air control. “Interestingly, it was not nicotine or nicotine solvents, but other additives in e-cigarettes that affected respiratory cells used in our study,” Goniewicz said.
Goniewicz said further studies are needed to investigate the effect of individual flavoring chemicals in e-cigarette liquids and the effect of combinations of these ingredients, MedPageToday reports. Researchers also need to study different brands of flavorings with the same flavor name. “Our study indicates that testing toxicity of ENDS products should not be limited to individual flavoring chemicals, since the ENDS liquids are complex mixtures, and other product features (e.g., voltage) contribute to overall toxicity of ENDS aerosol.”