Objective: We aimed to evaluate the association between environmental tobacco smoke (ETS) exposure and urinary cotinine levels in current adolescent smokers and nonsmokers. The secondary objective was to explore the association between ETS exposure and nicotine dependence in adolescent smokers.
Methods: Using the results from a validation study for the 2012 Global Youth Tobacco Survey in Mexico, we quantified urinary cotinine levels in adolescent smokers and nonsmokers. We fitted a multivariate regression model to assess the association between household exposure to ETS and cotinine levels in adolescent smokers and nonsmokers. In addition, using the questionnaire's answers for morning cravings, we fitted a multivariate Poisson regression model to explore the association between household ETS exposure and nicotine dependence in adolescent smokers.
Results: For each day of household ETS exposure, cotinine levels increase by 5% in adolescent smokers compared to a 2% increase in nonsmokers, adjusting for the number of cigarettes smoked per week, age and sex (exp(β) 1.05; 95% confidence interval [CI] [1.00, 1.10]; p = .041). Morning cravings increase 11% for each day of household ETS exposure adjusting for the number of cigarettes smoked per week, age and sex (prevalence ratio [PR] 1.11; 95% CI [0.99, 1.25]; p = .064).
Conclusions: There is an association between ETS exposure and cotinine levels, and ETS may contribute to nicotine dependence in adolescent smokers. If confirmed, avoiding ETS exposure could prove helpful for addiction control and quitting in adolescents.
Implications: Evidence suggests that ETS increases cotinine levels in nonsmokers and adult smokers. However, no study has explored the association between ETS exposure and cotinine levels and addiction in adolescent smokers. This paper provides evidence of an association between ETS exposure and cotinine levels in adolescent smokers: each day of environmental tobacco smoke exposure at home increased cotinine levels by 5% among smokers. In addition, morning cravings in adolescent smokers increased 11% for every day of ETS exposure. ETS exposure is a significant source of nicotine for adolescent smokers and could play an important role in addiction.