An in vitro evaluation of e-vapor products: The contributions of chemical adulteration, concentration, and device power.

Abstract

Homemade e-liquids and power-adjustable vaping devices may carry higher risks than commercial formulations and fixed-power devices. This study used human macrophage-like and bronchial epithelial (NHBE) cell cultures to investigate toxicity of homemade e-liquids containing propylene glycol and vegetable glycerin (PG/VG), nicotine, vitamin E acetate (VEA), medium-chain fatty acids (MCFAs), phytol, and cannabidiol (CBD). SmallAir™ organotypic epithelial cultures were exposed to aerosols generated at different power settings (10-50 W). Carbonyl levels were measured, and endpoints reflecting epithelial function (ciliary beating frequency [CBF]), integrity (transepithelial electrical resistance [TEER]), and structure (histology) were investigated. Treatment with nicotine or VEA alone or with PG/VG did not impact cell viability. CBD, phytol, and lauric acid caused cytotoxicity in both culture systems and increased lipid-laden macrophages. Exposure of SmallAir™ organotypic cultures to CBD-containing aerosols resulted in tissue injury and loss of CBF and TEER, while PG/VG alone or with nicotine or VEA did not. Aerosols generated with higher power settings had higher carbonyl concentrations. In conclusion, the presence and concentration of certain chemicals and device power may induce cytotoxicity in vitro. These results raise concerns that power-adjustable devices may generate toxic compounds and suggest that toxicity assessments should be conducted for both e-liquid formulations and their aerosols.