Do cigarette warning labels reduce smoking? Paradoxical effects among adolescents

Objective: To examine the association between adolescents' knowledge of cigarette warning labels and actual smoking behavior. Design: Cohort analytic study. Setting: Four public high schools in northern California. Subjects: Seventeen hundred forty-seven ninth graders (mean age, 14.9 years). Students from 2 of the schools (n=803) were observed for approximately 3 months. Main Outcome Measures: Self-reported knowledge of warning labels was assessed at baseline. Self-reports of smoking behavior were completed at baseline and at follow-up. Results: Greater knowledge of cigarette package warning labels was significantly associated with higher levels of smoking. Knowledge of warning labels on magazine and billboard advertisements did not differ significantly by level of smoking. In the longitudinal sample, greater knowledge of cigarette package warning labels was significantly associated with a subsequent increase in smoking, controlling for the baseline level of smoking, sex, ethnicity, and knowledge of warning labels on cigarette advertisements (odds ratio [OR], 1.22; 95% confidence interval [CI], 1.02-1.46). Knowledge of warning labels on cigarette advertisements was not associated with a significant change in smoking behavior (OR, 1.06; 95% CI, 0.82-1.35). Conclusions: Sizable proportions of adolescent smokers are not seeing, reading, or remembering cigarette warning labels. In addition, knowledge of warning labels on cigarette packages and advertisements is not associated with reduced smoking. The current warning labels are ineffective among adolescents.