Composition analysis of e-liquids and their effects on healthy liver and pharyngeal carcinoma cell lines

Electronic cigarettes have become popular worldwide in recent years despite the effects on health yet to be known. The lack of regulations brings a problem of inconsistency between ingredients and the product label. We aimed to analyse the contents of widely used e-liquids and their effects on two different cell lines. Eleven e-liquid samples were selected according to their availability and popularity. Nicotine, propylene glycol, glycerine, and volatile compounds in e-liquids were analysed by HPLC and GC. MTT cell viability assay was used to determine the effects of e-liquids on Transformed human normal liver epithelial cell line (THLE-2) and human pharyngeal carcinoma cell line (Detroit 562). Nicotine amounts were found to be consistent with product labels. PG and GLY were not only different between brands but also for products within the same brand. THLE-2 cell viability was inversely correlated with e-liquid concentration. However, decreases in cell viability were not correlated with nicotine amount. Interestingly, effects of several samples on Detroit 562 cells were triphasic; decrease in viability at lower doses, cell survival in mid-concentrations and loss of viability in highest doses. The analytical composition of e-liquids differs greatly among products which corresponds to different cellular effects. Viability of cancer cells does not change in a dose-dependent manner might suggest the cellular differences play role in the outcome of these products.