title: Group Waterpipe Tobacco Smoking Increases Smoke Toxicant Concentration.
abstract: BACKGROUND
  Waterpipe tobacco smoking is a global health concern. Laboratory research has focused on individual waterpipe users while group use is common. This study examined user toxicant exposure and smoke toxicant yield associated with individual and group waterpipe smoking.
  
  
  METHODS
  Twenty-two pairs of waterpipe smokers used a waterpipe individually and as a dyad. Before and after smoking, blood was sampled and expired carbon monoxide (CO) measured; puff topography was recorded throughout. One participant from each pair was selected randomly and their plasma nicotine and expired air CO concentrations were compared when smoking alone to when smoking as part of a dyad. Recorded puff topography was used to machine-produce smoke that was analyzed for toxicant content.
  
  
  RESULTS
  There was no difference in mean plasma nicotine concentration when an individual smoked as part of a dyad (mean = 14.9 ng/ml; standard error of the mean [SEM] = 3.0) compared to when smoking alone (mean = 10.0 ng/ml; SEM = 1.5). An individual smoking as part of as a dyad had, on average, lower CO (mean = 15.8 ppm; SEM = 2.0) compared to when smoking alone (mean= 21.3 ppm; SEM = 2.7). When two participants smoked as a dyad they took, on average, more puffs (mean = 109.8; SEM = 7.6) than a singleton smoker (mean = 77.7; SEM = 8.1) and a shorter interpuff interval (IPI; dyad mean = 23.8 seconds; SEM = 1.9; singleton mean = 40.8 seconds; SEM = 4.8). Higher concentrations of several toxicants were observed in dyad-produced smoke.
  
  
  CONCLUSIONS
  Dyad smoking may increase smoke toxicant content, likely due to the dyad's shorter IPIs and greater puff number. More work is needed to understand if group waterpipe smoking alters the health risks of waterpipe tobacco smoking.
  
  
  CONCLUSIONS
  This study is the first to measure toxicants in smoke generated from a waterpipe when used by a dyad. Relative to smoke generated by a singleton, dyad smoke had higher concentration of some toxicants. These differences may be attributed to differences in puffing behavior, specifically the shorter IPI and greater puff number observed in the dyad condition. Relative to singleton smokers, dyad smokers were exposed to less CO, but nicotine exposure did not differ. More work is needed to assess the health effects of inhalation of more toxicant-laden smoke during group waterpipe use.
authors.affiliation: Center for the Study of Tobacco Products, Department of Psychology, Virginia Commonwealth University, Richmond, VA;
authors.forename: Carolina P
authors.initials: CP
authors.lastname: Ramôa
authors.affiliation: Center for the Study of Tobacco Products, Department of Psychology, Virginia Commonwealth University, Richmond, VA; Department of Mechanical Engineering, American University of Beirut, Beirut, Lebanon.
authors.forename: Alan
authors.initials: A
authors.lastname: Shihadeh
authors.affiliation: Department of Mechanical Engineering, American University of Beirut, Beirut, Lebanon.
authors.forename: Rola
authors.initials: R
authors.lastname: Salman
authors.affiliation: Center for the Study of Tobacco Products, Department of Psychology, Virginia Commonwealth University, Richmond, VA; teissenb@vcu.edu.
authors.forename: Thomas
authors.initials: T
authors.lastname: Eissenberg
mesh_terms: D000280:Administration, Inhalation; D000293:Adolescent; D000328:Adult; D002248:Carbon Monoxide / Q000032:analysis / Q000097:blood; D005260:Female; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D009538:Nicotine / Q000032:analysis / Q000097:blood; D011897:Random Allocation; D012906:Smoke / Q000009:adverse effects / Q000032:analysis*; D012907:Smoking / Q000009:adverse effects* / Q000097:blood*; D012931:Social Environment; D014028:Tobacco Smoke Pollution / Q000009:adverse effects / Q000032:analysis; D055815:Young Adult; D014026:Nicotiana
chemical_list: D012906:Smoke; D014028:Tobacco Smoke Pollution; D009538:Nicotine; D002248:Carbon Monoxide