Evaluating the health effects of electronic cigarette refill

Determining the toxicity of electronic cigarette refill fluids is difficult due to the thousands of products sold worldwide. Refill fluids contain many flavor chemicals at varying concentration that can influence refill fluid toxicity. We have found that popular refill fluids with high concentrations (>1 mg/ml) of flavor chemicals decreased cultured lung cell survival. To help us better select and screen for potential toxic products, we identified 53 refill fluids in online forums that users reported made them ill. We purchased these refill fluids from local and online shops, and call this collection our “sickness-inducing” library or SIL. In this project, we propose three Specific Aims to test the hypothesis that refill fluids in the SIL have high concentrations of flavor chemicals that negatively affect cultured lung cells and human health. Specific Aim 1: Determine the toxicity for each refill fluid and a subset of flavor chemicals in the SIL. Specific Aim 2: Evaluate the mode-of-action of a subset of authentic standards of flavor chemicals at non-lethal concentrations. Specific Aim 3: Determine if humans using popular SIL products have elevated biomarkers of harm in urine and altered gene expression in nasal scrapes. Flavor chemicals have been identified and quantified in all SIL products. Refill fluids containing “authentic standards” of flavor chemicals found in high concentrations will be made by using appropriate solvents for cytotoxicity testing. We will also look at the effects of each chemical on cultured lung cells after exposing them to refill fluids at different doses and observing them in time-lapse videos. In our human study, we will recruit human participants using these products and compare their biological samples (urine and nasal) to non-smoker groups using RNA-seq (a technology that allows us to detect changes in gene expression). Biomarkers of harm can be detected by commercial enzyme-linked assay kits. This will be the first translational study relating the concentration of refill fluid flavor chemicals to human health using a sickness-inducing library. Data will be useful to regulatory agencies, healthcare professionals, and the public. The proposed project directly addresses TRDRP’s research priorities in Environmental Exposure and Toxicology, Pulmonary Biology and Lung Disease, and Tobacco Control.