Understanding the effect of waterpipe size on smoking behavior, toxicant exposures and subjective experiences

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Waterpipe (WP) tobacco smoking—also known as hookah—continues to be a popular method of tobacco smoking in the United States (US), particularly among young adults. Similar to cigarettes, accumulating evidence shows that WP smoking can lead to nicotine dependence, lung cancer and cardiopulmonary diseases. Recognizing the seriousness of the WP epidemic in the US, the Food and Drug Administration (FDA) now regulates the manufacture, sale, and distribution of WP products, including the different components and configurations of the WP device. However, regulations specific to WP remains limited. One of the main regulatory routes with great potential for WP control is the size of the WP device. Compared with traditional cigarettes that are manufactured in standard sizes, WPs are available in many sizes that can vary significantly in pipe height and bowl volume. Converging lines of evidence regarding the toxicant exposure associated with WP smoking indicate that WP size is an important factor in determining exposures to carbon monoxide (CO) and other toxicant emissions. In addition, there is a prevailing public misconception regarding the perception of harm attributed to WP smoking. The majority of WP smokers believe that WP is less addictive and less harmful than cigarette smoking. Such misconceptions are reinforced by the marketing of smaller sizes of WP. In fact, many online WP retailers in the US advertise small WPs (aka, mini hookahs) as “excellent choice for a first hookah” and “best hookahs for beginners” which make them appear like perfect “starter sizes” for otherwise WP-naïve individuals. Therefore, it is logical that the dimensions of the WP itself will influence harm perception and smoking behavior and in turn will alter the levels of exposure to toxicants such as CO and nicotine among WP smokers. However, empirical evidence regarding the effect of WP size–a key question from a regulatory standpoint–on WP smokers' experiences and exposures continues to be lacking. In this project, we will assess the effect of WP size on smoking behavior, toxicant exposures and subjective experiences among WP smokers. We hypothesize that smoking a smaller size WP will lead to a more pronounced effect on puffing parameters, exposure to CO and nicotine, harm perception, satisfaction and craving compared to smoking a larger size WP. We will enroll 40 young adult WP smokers (21-39 years) to undergo a 2X3 crossover study design, where the within-subject factors are time (pre-post WP smoking) and study condition (small WP vs. medium WP vs. large WP). Accordingly, each participant will complete three independent sessions of WP smoking (45 min each) that differ by WP size, while measurement of puff topography, subjective experiences, harm perception, and exposure to nicotine and CO will be conducted. This project is innovative because it will provide the first evidence to guide the FDA in terms of the potential impact of regulating WP size on smokers’ experiences and exposures. Most importantly, this project will help the FDA in developing size-specific regulatory standards to control the marketing and sales of WP devices and to protect public health.