Does film smoking promote youth smoking in middle-income countries? A longitudinal study among Mexican adolescents

Objective: To determine whether exposure to smoking imagery in films predicts smoking onset among neversmoking Mexican adolescents. Methods: The analytic sample was comprised of 11- to 14-year-old secondary school students who reported never having tried smoking at baseline, 83% (1,741/ 2,093) of whom were successfully followed-up after 1 year. Exposure to 42 popular films that contained smoking was assessed at baseline, whereas smoking behavior and risk factors were assessed at baseline and at follow-up. Logistic regression was used to estimate bivariate and adjusted relative risks (ARR) of trying smoking and current smoking at follow-up. Results: At follow-up, 36% reported having tried smoking and 8% reported having smoked in the previous month. Students who were successfully followed-up were exposed to an average of 43.8 minutes of smoking in the films they reported viewing at baseline. ARRs indicated that students in the two highest levels of exposure to film smoking were more than twice as likely to have smoked in the previous 30 days at follow-up [ARR3v1 = 2.44; 95% confidence interval (CI), 1.31-4.55; ARR4v1 = 2.23; 95% CI, 1.19-4.17]. The ARR of having tried smoking by the time of follow-up reached statistical significance only when comparing the third highest to the lowest exposure group (ARR3v1 = 1.54; 95% CI, 1.01-2.64). Having a parent or best friend who smoked at baseline were the only other variables that independently predicted both outcomes. Conclusions: Exposure to movie smoking is a risk factor for smoking onset among Mexican youth, although this risk appears weaker than in countries with stronger tobacco marketing regulations.