An interventional study of Waterpipe size in Waterpipe Size, sponsored by The University of Texas at Arlington. Completed at 1 site in United States. Open to participants aged 21 Years to 39 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-11-05.
Sponsored by The University of Texas at Arlington · Not applicable, Interventional, and Other
The goal of this clinical trial is to learn how waterpipe (WP) size affects smoking behavior, toxicant exposure, and subjective experiences in young adult WP smokers (ages 21-39). The main questions it aims to answer are:
Participants will smoke small, medium, and large WPs in separate sessions. Researchers will measure puffing behavior, saliva nicotine, exhaled carbon monoxide, and survey responses before and after each session.
This study will examine the effect of waterpipe (WP) size manipulation on smoking behavior, toxicant exposure, and subjective experiences among young adult WP smokers. A total of 40 participants ages 21-39 will complete a 2x3 crossover design, where the within-subject factors are time (pre vs. post WP smoking) and study condition (small vs. medium vs. large). Each participant will attend three 45-minute laboratory sessions, each using a different WP size.
Aim 1: To examine the effect of WP size on puffing behavior and toxicant exposure. Puff topography parameters (puff number, duration, average puff volume, total inhaled volume, and inter-puff interval) will be measured during smoking. Exhaled CO and saliva nicotine concentrations will be measured pre- and post-session.
Aim 2: To examine the effect of WP size on harm perception and subjective experiences. Outcomes include harm perception, WP Evaluation Scale, Duke Sensory Questionnaire, Questionnaire of Smoking Urges (brief), and Minnesota Nicotine Withdrawal Scale.
This project will generate novel evidence on how WP size influences smoking behavior, exposure to nicotine and CO, and user perceptions. Findings will inform the FDA on the potential impact of WP size regulation and help guide the development of size-specific standards to protect public health.
The University of Texas at Arlington is the lead sponsor of 37 studies on the registry; 11 are open to participants now.
Of its 8 completed or terminated interventional studies of FDA-regulated products, 2 (25%) have results posted.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
waterpipe regular smokers will be invited for 3 lab visits where they are allocated (random order) to smoke 3 waterpipe different sizes.
Other: Waterpipe size
Participants will have 3 lab visits where they are allocated (random order) to smoke a small waterpipe in one visit, smoke a medium waterpipe in a second visit and smoke a large waterpipe in a third visit.
Waterpipe Evaluation Scale
An 11-item questionnaire assessing participants' subjective experience of smoking waterpipe (WP) tobacco. Each item is scored on a 7-point Likert scale (1 = "not at all" to 7 = "extremely"). For analysis, item scores were averaged across the 11 items to produce a mean WES score for each WP size, with higher scores indicating a more satisfactory smoking experience. The scale captures aspects such as satisfaction, taste, cravings, and sensory enjoyment in the throat and chest.
Time frame: Immediately after the exposure (smoking)
Duke Sensory Questionnaire
A 9-item questionnaire assessing participants' sensory experience of smoking waterpipe (WP) tobacco. Each item is scored on a 7-point Likert scale (1 = "not at all" to 7 = "extremely"). Item scores were averaged across the 9 items to produce a mean DSQ score for each WP size, with higher scores indicating a more positive sensory experience (e.g., satisfaction, perceived nicotine strength, and puff intensity).
Time frame: Immediately after the exposure (smoking)
Harm Perception Questionnaire
This is a 3-item scale assessing participants' perception of the harmfulness of waterpipe (WP) tobacco smoking. Each item is scored on a 7-point Likert scale ranging from 1 = "a lot less harmful" to 7 = "a lot more harmful." Item scores were averaged across the 3 items to produce a mean harm perception score for each WP size, with higher scores indicating greater perceived harm.
Time frame: Immediately after the exposure (smoking)
Saliva Nicotine
How participants' nicotine concentrations change based on the different smoked waterpipe sizes
Time frame: Immediately after the exposure (smoking)
Puff Topography: Smoking Time
The total time spent smoking during a single WP session, measured in minutes. Longer times indicate greater duration of smoking across WP sizes.
Time frame: During the exposure (smoking), up to 45 mins
Puff Topography: Cumulative Puff Time
The total time spent actively inhaling smoke across all puffs in a WP session, measured in minutes using a puff topography device. Higher values indicate more total inhalation time.
Time frame: During the exposure (smoking), up to 45 mins
Puff Topography: Puff Duration
The average length of each puff in seconds, measured using a puff topography device in the WP hose. Longer puff duration indicates deeper inhalation per puff.
Time frame: During the exposure (smoking), up to 45 mins
Puff Topography: Average Flow Rate
The average rate of smoke inhaled per second during puffing, measured in liters per minute with a puff topography device. Higher flow rates indicate faster inhalation.
Time frame: During the exposure (smoking), up to 45 mins
Puff Topography: Number of Puffs
The total number of puffs taken during a WP session, measured using a puff topography device. Higher counts indicate more frequent puffing.
Time frame: During the exposure (smoking), up to 45 mins
Puff Topography: Total Smoke Volume Inhaled
Total smoke inhaled during a single WP session, measured in liters using a puff topography device in the WP hose. Higher values indicate greater smoke intake across WP sizes.
Time frame: During the exposure (smoking), up to 45 mins
Puff Topography: Puff Volume Average
Mean volume of each puff during a WP session, measured in liters using a puff topography device in the WP hose. Higher values indicate larger puff sizes across WP sizes.
Time frame: During the exposure (smoking), up to 45 mins
Puff Topography: Maximum Puff Volume
The largest single puff volume inhaled during a WP session, measured in liters using a puff topography device. Higher values indicate the strongest inhalation effort across puffs.
Time frame: During the exposure (smoking), up to 45 mins
| Milestone | Small → Medium → Large | Small → Large → Medium | Medium → Large → Small | Medium → Small → Large | Large → Medium → Small | Large → Small → Medium |
|---|---|---|---|---|---|---|
| Started | 3 | 7 | 11 | 6 | 6 | 7 |
| Completed | 3 | 7 | 11 | 6 | 6 | 7 |
| Not completed | 0 | 0 | 0 | 0 | 0 | 0 |
| Milestone | Small → Medium → Large | Small → Large → Medium | Medium → Large → Small | Medium → Small → Large | Large → Medium → Small | Large → Small → Medium |
|---|---|---|---|---|---|---|
| Started | 3 | 7 | 11 | 6 | 6 | 7 |
| Completed | 3 | 7 | 11 | 6 | 6 | 7 |
| Not completed | 0 | 0 | 0 | 0 | 0 | 0 |
| Milestone | Small → Medium → Large | Small → Large → Medium | Medium → Large → Small | Medium → Small → Large | Large → Medium → Small | Large → Small → Medium |
|---|---|---|---|---|---|---|
| Started | 3 | 7 | 11 | 6 | 6 | 7 |
| Completed | 3 | 7 | 11 | 6 | 6 | 7 |
| Not completed | 0 | 0 | 0 | 0 | 0 | 0 |
| Milestone | Small → Medium → Large | Small → Large → Medium | Medium → Large → Small | Medium → Small → Large | Large → Medium → Small | Large → Small → Medium |
|---|---|---|---|---|---|---|
| Started | 3 | 7 | 11 | 6 | 6 | 7 |
| Completed | 3 | 7 | 11 | 6 | 6 | 7 |
| Not completed | 0 | 0 | 0 | 0 | 0 | 0 |
| Milestone | Small → Medium → Large | Small → Large → Medium | Medium → Large → Small | Medium → Small → Large | Large → Medium → Small | Large → Small → Medium |
|---|---|---|---|---|---|---|
| Started | 3 | 7 | 11 | 6 | 6 | 7 |
| Completed | 3 | 7 | 11 | 6 | 6 | 7 |
| Not completed | 0 | 0 | 0 | 0 | 0 | 0 |
An 11-item questionnaire assessing participants' subjective experience of smoking waterpipe (WP) tobacco. Each item is scored on a 7-point Likert scale (1 = "not at all" to 7 = "extremely"). For analysis, item scores were averaged across the 11 items to produce a mean WES score for each WP size, with higher scores indicating a more satisfactory smoking experience. The scale captures aspects such as satisfaction, taste, cravings, and sensory enjoyment in the throat and chest.
| units on a scale | Small Waterpipe | Medium Waterpipe | Large Waterpipe |
|---|---|---|---|
| Waterpipe Evaluation Scale | 4.2 ± 0.8 | 4.4 ± 0.7 | 4.7 ± 0.8 |
A 9-item questionnaire assessing participants' sensory experience of smoking waterpipe (WP) tobacco. Each item is scored on a 7-point Likert scale (1 = "not at all" to 7 = "extremely"). Item scores were averaged across the 9 items to produce a mean DSQ score for each WP size, with higher scores indicating a more positive sensory experience (e.g., satisfaction, perceived nicotine strength, and puff intensity).
| units on a scale | Small Waterpipe | Medium Waterpipe | Large Waterpipe |
|---|---|---|---|
| Duke Sensory Questionnaire | 4.4 ± 0.9 | 4.0 ± 0.8 | 3.8 ± 0.9 |
This is a 3-item scale assessing participants' perception of the harmfulness of waterpipe (WP) tobacco smoking. Each item is scored on a 7-point Likert scale ranging from 1 = "a lot less harmful" to 7 = "a lot more harmful." Item scores were averaged across the 3 items to produce a mean harm perception score for each WP size, with higher scores indicating greater perceived harm.
| units on a scale | Small Waterpipe | Medium Waterpipe | Large Waterpipe |
|---|---|---|---|
| Harm Perception Questionnaire | 3.5 ± 0.5 | 3.7 ± 0.2 | 3.8 ± 0.2 |
How participants' nicotine concentrations change based on the different smoked waterpipe sizes
| ng/mL | Small Waterpipe | Medium Waterpipe | Large Waterpipe |
|---|---|---|---|
| Saliva Nicotine | 1065.5 ± 247.4 | 620.2 ± 123.2 | 701.4 ± 118.9 |
The total time spent smoking during a single WP session, measured in minutes. Longer times indicate greater duration of smoking across WP sizes.
| Minutes | Small Waterpipe | Medium Waterpipe | Large Waterpipe |
|---|---|---|---|
| Puff Topography: Smoking Time | 38.05 ± 5.82 | 35.5 ± 7.23 | 36.27 ± 7.23 |
The total time spent actively inhaling smoke across all puffs in a WP session, measured in minutes using a puff topography device. Higher values indicate more total inhalation time.
| Minutes | Small Waterpipe | Medium Waterpipe | Large Waterpipe |
|---|---|---|---|
| Puff Topography: Cumulative Puff Time | 5.10 ± 2.67 | 5.10 ± 2.95 | 6.67 ± 4.02 |
The average length of each puff in seconds, measured using a puff topography device in the WP hose. Longer puff duration indicates deeper inhalation per puff.
| Seconds | Small Waterpipe | Medium Waterpipe | Large Waterpipe |
|---|---|---|---|
| Puff Topography: Puff Duration | 2.15 ± 1.08 | 2.20 ± 1.03 | 2.45 ± 0.96 |
The average rate of smoke inhaled per second during puffing, measured in liters per minute with a puff topography device. Higher flow rates indicate faster inhalation.
| L/min | Small Waterpipe | Medium Waterpipe | Large Waterpipe |
|---|---|---|---|
| Puff Topography: Average Flow Rate | 15.14 ± 6.11 | 16.65 ± 6.05 | 18.92 ± 7.96 |
The total number of puffs taken during a WP session, measured using a puff topography device. Higher counts indicate more frequent puffing.
| Puffs | Small Waterpipe | Medium Waterpipe | Large Waterpipe |
|---|---|---|---|
| Puff Topography: Number of Puffs | 161.05 ± 90.39 | 162.31 ± 122.51 | 182.90 ± 138.46 |
Total smoke inhaled during a single WP session, measured in liters using a puff topography device in the WP hose. Higher values indicate greater smoke intake across WP sizes.
| Liters | Small Waterpipe | Medium Waterpipe | Large Waterpipe |
|---|---|---|---|
| Puff Topography: Total Smoke Volume Inhaled | 76.82 ± 50.67 | 79.85 ± 48.27 | 116.19 ± 63.18 |
Mean volume of each puff during a WP session, measured in liters using a puff topography device in the WP hose. Higher values indicate larger puff sizes across WP sizes.
| Liters | Small Waterpipe | Medium Waterpipe | Large Waterpipe |
|---|---|---|---|
| Puff Topography: Puff Volume Average | 0.57 ± 0.39 | 0.64 ± 0.45 | 0.78 ± 0.42 |
The largest single puff volume inhaled during a WP session, measured in liters using a puff topography device. Higher values indicate the strongest inhalation effort across puffs.
| Liters | Small Waterpipe | Medium Waterpipe | Large Waterpipe |
|---|---|---|---|
| Puff Topography: Maximum Puff Volume | 1.21 ± 0.50 | 1.34 ± 0.64 | 1.62 ± 0.62 |
Collected over Each participant was monitored during and immediately after three laboratory smoking sessions (~45 minutes each) separated by ≥48 hours (~1 week total monitoring per participant). This monitoring process was carried out for all participants over the approximate 23-month study period.. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Small Waterpipe | 0/40 (0%) | 0/40 (0%) | 0/40 (0%) |
| Medium Waterpipe | 0/40 (0%) | 0/40 (0%) | 0/40 (0%) |
| Large Waterpipe | 0/40 (0%) | 0/40 (0%) | 0/40 (0%) |
waterpipe regular smokers will be invited for 3 lab visits where they are allocated (random order) to smoke 3 waterpipe different sizes.
| Age, Continuous(years) | Waterpipe Regular Smokers |
|---|---|
| Mean | 24.9 ± 3.5 |
| Sex: Female, Male(Participants) | Waterpipe Regular Smokers |
|---|---|
| Female | 11 |
| Male | 29 |
| Race (NIH/OMB)(Participants) | Waterpipe Regular Smokers |
|---|---|
| American Indian or Alaska Native | 0 |
| Asian | 26 |
| Native Hawaiian or Other Pacific Islander | 0 |
| Black or African American | 5 |
| White | 9 |
| More than one race | 0 |
| Unknown or Not Reported | 0 |
| Region of Enrollment(Participants) | Waterpipe Regular Smokers |
|---|---|
| United States | 40 |
| Saliva Nicotine(ng/mL) | Waterpipe Regular Smokers |
|---|---|
| Mean | 9 ± 3.5 |
| Exhaled Carbon Monoxide(PPM) | Waterpipe Regular Smokers |
|---|---|
| Mean | 1.2 ± 0.2 |
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The University of Texas at Arlington