Research articleWaterpipe Tobacco and Cigarette Smoking: Direct Comparison of Toxicant Exposure
Introduction
Smoking tobacco using a waterpipe (hookah, narghile, shisha; Figure 1) is a global phenomenon,1 especially among adolescents and young adults. For example, among adolescents, current waterpipe tobacco smoking prevalence is approximately 30% in Estonia2; Latvia3; and Beirut, Lebanon4; 5%–17% of some adolescent populations in the U.S. may be current waterpipe tobacco smokers.5, 6 Among university students, current waterpipe tobacco-smoking prevalence is 33% in Karachi, Pakistan,7 and 10%–20% in the U.S.8, 9 Where no data are available, waterpipe tobacco smoking's popularity is demonstrated by businesses that facilitate it (e.g., hookah cafés) in countries such as Australia, Brazil, Canada, France, New Zealand, and South Africa. Thus, physicians across the globe can expect that some of their patients are current waterpipe tobacco smokers. The more informed these physicians are about the risks of this tobacco use method, the better they can address these risks with their waterpipe-using patients.
One way of estimating waterpipe risk is to compare waterpipe-smoke toxicant content (or yield) to cigarette-smoke toxicant content. Such comparisons are made using smoke generated by a machine and reveal that, relative to smoke generated from a cigarette, the smoke generated from a waterpipe yields alarming quantities of carcinogens; carbon monoxide (CO); nicotine; and “tar.”10, 11, 12 However, machine-generated smoke toxicant yields may not be an accurate indication of actual smoker toxicant exposure, and no controlled, head-to-head comparison of smoker toxicant exposure for waterpipes and cigarettes has been reported. Such a comparison would address the oft-reported perception that, relative to cigarette smoking, waterpipe tobacco smoking presents reduced health risks.13, 14, 15
Indeed, understanding the relative smoker toxicant exposure associated with waterpipe and cigarette smoking is of great interest: The two have been compared briefly and indirectly in virtually every empirical study in which waterpipe toxicant exposure has been measured.16, 17, 18, 19, 20 However, comparisons of toxicant exposure across different tobacco use methods are more than inherently interesting: The observation that cigarette and smokeless tobacco use are associated with equivalent peak blood nicotine concentration21 provided support for the use of nicotine replacement medications for treatment of smokeless tobacco users.22 Perhaps most important, comparing the waterpipe and cigarette toxicant exposure can help physicians and other public health professionals address misperceptions driving the global spread of waterpipe use. Thus, the purpose of this study is to provide the first controlled, direct laboratory comparison of the toxicant exposure associated with waterpipe tobacco and cigarette smoking.
Waterpipe tobacco smokers who also smoked cigarettes participated in two laboratory sessions in which they smoked a waterpipe or a cigarette ad libitum. Outcomes included expired-air CO concentration; carboxyhemoglobin (COHb) and plasma nicotine levels; heart rate; and puff topography. Based on cross-study comparisons,23 it was hypothesized that, relative to cigarette smoking, waterpipe tobacco smoking would be associated with greater CO and nicotine exposure as well as greater puff number and volume.
Section snippets
Participants
Thirty-nine participants recruited in 2008–2009 from the Richmond VA community, using advertisements and word of mouth, provided informed consent for this study, which was approved by the Virginia Commonwealth University IRB. Of these 39, two withdrew and two were discontinued because of scheduling difficulties or protocol noncompliance. The blood samples for four of the remaining 35 participants returned results that were not valid, so the final sample consisted of 31 individuals (21 men; 22
Results
Of the 31 participants, five chose to use an additional half charcoal briquette during their waterpipe session; the pattern of results was not influenced by these five participants, so their data are included in all analyses described below.
For expired-air CO, statistical analysis revealed a significant condition by time interaction (F [1, 30]=36.9, p<0.001). For cigarette, mean (±SEM) pre-smoking CO level was 5.1±0.5 ppm and increased to 7.8±0.6 after smoking, while for waterpipe, mean
Discussion
Relative to a single cigarette, a single waterpipe-use episode is associated with similar peak plasma nicotine levels and three times greater peak COHb levels. The first 5 minutes of waterpipe smoking produced more than four times the increase in COHb as smoking an entire cigarette (i.e., first-5-minute increase of 145% for COHb vs 34% for a cigarette). The observation that heart rate changes mirrored blood nicotine levels supports the notion that, for waterpipes and cigarettes, nicotine doses
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