title: Perception of e-cigarette harm and its correlation with use among U.S. adolescents.
abstract: BACKGROUND
  U.S. adolescents increasingly use e-cigarettes. The perceived harm of e-cigarettes has not been described, nor has the correlation between harm perception and e-cigarette use been assessed. This study examines correlates of e-cigarette harm perception and use of e-cigarettes in a national survey.
  
  
  METHODS
  We used cross-sectional nationally representative data from the 2012 National Youth Tobacco Survey (n = 24,658). Cross-tabulations and multivariate ordered probit and logistic regression models were employed to assess relative harm perception and e-cigarette use.
  
  
  RESULTS
  Half of U.S. adolescents had heard of e-cigarettes. Of these, 13.2% (95% confidence interval [CI] = 11.7-14.9) and 4.0% (95% CI = 3.4-4.7) reported ever or currently using e-cigarettes, respectively. Of those aware of e-cigarettes, 34.2% (95% CI = 32.8-35.6) believed e-cigarettes were less harmful than cigarettes. Among those trying e-cigarettes, 71.8% (95% CI = 69.0-74.5) believed e-cigarettes were comparatively less harmful. Females and those ≥ 17 years old were more likely to perceive e-cigarettes as more harmful relative to cigarettes, while on average Whites, users of other tobacco products, and those with family members who used tobacco were more likely to perceive e-cigarettes as comparatively safer. Among cigarette-naive e-cigarette users, use of other tobacco products and perceived harm reduction by e-cigarettes were, respectively, on average associated with 1.6 and 4.1 percentage-point increases in e-cigarette use.
  
  
  CONCLUSIONS
  Perception of e-cigarettes as less harmful than conventional cigarettes was associated with increased e-cigarette use, including among cigarette-naive e-cigarette users. These findings should prompt further scientific investigation and merit attention from regulators.
authors.affiliation: Department of Pediatrics, New York University School of Medicine, New York, NY; stephen.amrock@med.nyu.edu.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Amrock
authors.affiliation: Department of Pediatrics, New York University School of Medicine, New York, NY;
authors.forename: Joseph
authors.initials: J
authors.lastname: Zakhar
authors.affiliation: Department of Pediatrics, New York University School of Medicine, New York, NY;
authors.forename: Sherry
authors.initials: S
authors.lastname: Zhou
authors.affiliation: Department of Pediatrics, New York University School of Medicine, New York, NY; Department of Environmental Medicine, New York University School of Medicine, New York, NY; Global Institute for Public Health, New York University, New York, NY.
authors.forename: Michael
authors.initials: M
authors.lastname: Weitzman
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology*; D001364:Awareness; D002648:Child; D003430:Cross-Sectional Studies; D066300:Electronic Nicotine Delivery Systems / Q000523:psychology* / Q000706:statistics & numerical data*; D005260:Female; D040261:Harm Reduction; D006801:Humans; D008297:Male; D010465:Perception; D012907:Smoking / Q000453:epidemiology / Q000523:psychology; D014481:United States / Q000453:epidemiology