title: Longitudinal study of viewing smoking in movies and initiation of smoking by children.
abstract: BACKGROUND
  Previous studies showed an association between viewing of smoking in movies and initiation of smoking among adolescents. However, all studies except one were cross-sectional, and none updated movie smoking exposure prospectively or assessed its influence on children.
  
  
  METHODS
  We enrolled elementary school students, 9 to 12 years of age, in a longitudinal study to assess the influence of movie smoking exposure on smoking initiation among children. Movie smoking content was coded for the most popular movie releases; exposure was assessed by asking children which movies they had seen, on the basis of unique lists of 50 movies sampled randomly from top box office hits and video rentals. Data collection occurred in 3 waves (the baseline survey and 2 follow-up surveys), approximately 1 year apart. Movie lists were updated for each data collection wave, to reflect recent releases. Movie smoking exposure was analyzed in relation to smoking initiation by the end of the study period.
  
  
  RESULTS
  Approximately 80% of the children's smoking exposure occurred through movies rated G, PG, or PG-13. Children's movie smoking exposure predicted smoking initiation significantly, after adjustment for multiple covariates including child and parent characteristics. The relative risks were 1.09, 1.09, and 1.07 for a 1-decile increase of movie smoking exposure measured at the baseline, second, and third data collection waves, respectively. The adjusted attributable risk of smoking initiation attributable to movie smoking exposure was 0.35.
  
  
  CONCLUSIONS
  Our study, which is the first to enroll children in elementary school and to update movie smoking exposure longitudinally, indicates that early exposure has as much influence on smoking risk as does exposure nearer the outcome. Overall, movie smoking may be responsible for at least one third of smoking initiation for children in this age group.
authors.affiliation: Department of Community and Family Medicine, Dartmouth Medical School, Lebanon, New Hampshire, USA. linda.titus-ernstoff@dartmouth.edu
authors.forename: Linda
authors.initials: L
authors.lastname: Titus-Ernstoff
authors.forename: Madeline A
authors.initials: MA
authors.lastname: Dalton
authors.forename: Anna M
authors.initials: AM
authors.lastname: Adachi-Mejia
authors.forename: Meghan R
authors.initials: MR
authors.lastname: Longacre
authors.forename: Michael L
authors.initials: ML
authors.lastname: Beach
mesh_terms: D000367:Age Factors; D002648:Child; D002652:Child Behavior / Q000523:psychology; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007100:Imitative Behavior; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008402:Mass Media; D009040:Motion Pictures; D009513:New Hampshire / Q000453:epidemiology; D011336:Probability; D018570:Risk Assessment; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology* / Q000523:psychology*; D013334:Students