Evaluation and Comparison of Impacts of Flavored Waterpipe Tobacco and Electronic Waterpipe E-Liquid Formulation Variations on Toxicant Yields and Particle Size Distribution in Mainstream Emissions

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Project Summary Waterpipe (WP) smoking has become a popular form of tobacco use in the US, especially among youth and young adults. These groups are particularly attracted to flavored WP tobacco (WPT). Sweet WPT flavors are preferred, with fruit flavors in particular leading to initiation and continued WP use, as well as the misperception of WP smoking as less harmful than cigarette smoking. WPT smoking has been linked to many of the same adverse health effects as cigarette smoking and releases many of the same harmful and potentially harmful constituents (HPHCs) as cigarettes, at 10-100 times increased levels. The popularity of flavored WP smoking has expanded in recent years to flavored tobacco-free alternatives, including electronic WP (EWP). EWP replaces the traditional WP bowl and heat source with an electronic head filled with flavored, nicotine-containing liquid (e-liquid), turning the WP into an electronic nicotine delivery system (ENDS). Given the rising popularity of other flavored ENDS, EWP may pose similar appeal and uptake concerns. EWP may be perceived as a safe WP alternative, but it has the potential to release the same harmful emissions as other ENDS. Yet nothing is known about the safety of EWP, or if it offers any harm reductions compared to WPT smoking. Flavored WP products may play an important role in the direct harms of WP smoking. EWP e-liquids and WPTs both use flavorants, sweet humectants (propylene glycol and glycerol), and sugars to enhance their appeal. These ingredients in cigarettes have been shown to form toxic aldehydes and furans during smoking. ENDS research shows that variations in e-liquid humectant content, as well as the presence of flavorings, can increase aldehydes emissions. Fundamental knowledge is lacking on the range of toxicants emissions across flavored WP products and the impact of variations in product formulations on toxic emissions and particle size distribution, a critical parameter in the delivery of toxicants to the human respiratory system. In order to regulate WP smoking and set product standards to reduce harms and public health impacts, it is imperative that US Food and Drug Administration have data to understand the impact of flavored WP smoking on exposure and how exposures may differ between traditional and alternative WP smoking platforms. This study will fill these gaps by evaluating and comparing the impact of variations in flavor profiles, humectants and sugar levels, and heating temperatures, in a variety of commercially available WPTs and EWP e-liquids on yields of HPHCs and other toxicants as well as particle size distribution in mainstream WP emissions. This will also be the first study to measure toxicant emissions from EWP use. This study is an essential step in providing robust, fundamental information on WP product formulations and toxicant emissions to better understand relative harms associated with flavored WP smoking and establish a knowledge base to inform regulatory actions surrounding WP product standards.