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A7545 - Identification of Respiratory Health Effects and Cytotoxic Flavor Chemicals in Popular Electronic Cigarette Refill Fluids
Author Block: M. Hua1, E. Omaiye1, W. Luo2, K. J. McWhirter3, J. F. Pankow2, P. Talbot4; 1Environmental Toxicology Graduate Program, UC Riverside, Riverside, CA, United States, 2Department of Civil and Environmental Engineering, Portland State University, Portland, OR, United States, 3Department of Chemistry, Portland State University, Portland State University, OR, United States, 4Department of Molecular, Cell and Systems Biology, UC Riverside, Riverside, CA, United States.
RATIONALE: Few chemical flavors in electronic cigarette (EC) refill fluids have inhalation safety data available for humans. With the increasing prevalence of EC and their popularity worldwide, it is important to assess the respiratory effects associated with chemical flavors in EC refill fluids. Studies investigating the relationship between chemical flavors and their concentrations on the respiratory health is lacking. The goal of this study was to understand the relationship between popular flavorings and perceived respiratory health effects in EC users, and, to further identify and assess cytotoxic flavor chemicals in popular refill fluids purchased from local stores. METHODS: To study the relationship between EC flavors and health effects, we surveyed 2,753 respondents from UC Riverside and online health forums. The survey asked respondents about their EC flavor preferences and respiratory health effects associated with EC refill fluids. Additionally, 20 popular refill fluid brands were purchased from four local stores. The flavor chemicals in these popular brands were identified and quantified by gas-chromatography mass-spectrometry, then visualized by heatmaps which ranked their increasing potency from available rat-oral toxicity data. Cytotoxicity for all 20 samples was evaluated by creating authentic standards for the flavor chemicals present in highest concentration and evaluated using human bronchial epithelial (BEAS-2B) cells in MTT assay. RESULTS: Most EC users who reported using EC refill fluids with flavorings identified Berries/Citrus [n=559 (70.85%)]; Sweets [n=406 (51.46%)]; and Bakery [n=321(40.68%)] as popular. In the survey, most negative effects were reported in respiratory system (n=111), and related to “Aromatic”, “Buttery/Caramel/Vanilla”, and “Menthol” flavors. Identification of the 20 popular refill fluids revealed the presence of 99 flavor chemicals. 80% of the refill fluids were cytotoxic in the MTT assay. Some chemicals that were prevalent among the products and at high concentrations (>1 mg/ml), such as ethyl maltol, furaneol, maltol, ethyl vanillin, and benzyl alcohol were most cytotoxic according to IC50. Product labels did not have information on flavor chemicals or their concentrations. CONCLUSION: Our results suggest that EC users associate particular flavor categories of refill fluids with adverse respiratory effects. Some dominant flavor chemicals were found in high concentrations in EC refill fluids, and those at the highest concentrations impaired survival of human respiratory cells in vitro. Physicians and regulatory agencies should be aware that flavor chemicals are often present in EC products at concentrations that could negatively impact health of the respiratory system.