title: Smoking topography, brand switching, and nicotine delivery: results from an in vivo study.
abstract: OBJECTIVE
  Exposure to toxins in tobacco smoke is influenced by how a cigarette is smoked. Cigarettes have been designed to allow for a range of puffing behavior and to provide different, nonlinear tar and nicotine yields in response to different puffing profiles. However, puffing behavior and its influence upon risk-exposure has yet to be assessed outside the laboratory, in smokers' natural environment.
  
  
  METHODS
  Fifty-nine adult smokers used a portable device to measure smoking topography over the course of three 1-week trials. Participants were asked to smoke their usual "regular yield" brand through the device for trial 1 and again, 6 weeks later, at trial 2. Half the subjects were then randomly assigned to switch to a "low-yield" brand for trial 3.
  
  
  RESULTS
  The findings show a high degree of stability in puffing behavior within the same subject over time but considerable variability between smokers. Smokers who were switched to a "low-yield" cigarette increased their total smoke intake per cigarette by 40% (P = 0.007), with no significant change in their salivary cotinine levels. Cigarettes smoked per day and nicotine yield were only weakly associated with salivary cotinine levels; however, salivary cotinine was strongly associated with a composite measure that included cigarettes per day, brand elasticity, and puffing behavior (sr = 0.61, P < 0.001).
  
  
  CONCLUSIONS
  These findings provide strong evidence of behavioral compensation to low-yield cigarettes from in vivo measures of smoking behavior. The findings also show the importance of brand elasticity and smoking topography in predicting nicotine uptake and smoke exposure.
authors.affiliation: Department of Psychology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1. dhammond@uwaterloo.ca
authors.forename: David
authors.initials: D
authors.lastname: Hammond
authors.forename: Geoffrey T
authors.initials: GT
authors.lastname: Fong
authors.forename: K Michael
authors.initials: KM
authors.lastname: Cummings
authors.forename: Andrew
authors.initials: A
authors.lastname: Hyland
mesh_terms: D000328:Adult; D003367:Cotinine / Q000032:analysis; D004781:Environmental Exposure; D005260:Female; D005731:Ganglionic Stimulants / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009538:Nicotine / Q000008:administration & dosage*; D011897:Random Allocation; D015203:Reproducibility of Results; D012119:Respiration; D018570:Risk Assessment; D012463:Saliva / Q000737:chemistry; D012907:Smoking / Q000523:psychology*; D014118:Toxins, Biological
chemical_list: D005731:Ganglionic Stimulants; D014118:Toxins, Biological; D009538:Nicotine; D003367:Cotinine