title: Changes in adolescents' sources of cigarettes.
abstract: OBJECTIVE
  No previous research has tracked changes in teen sources for tobacco. Such information might help public health officials to target tobacco control efforts more precisely. This investigation used a two-year longitudinal design to determine (1) how adolescents' sources change and (2) whether the timing of smoking onset and duration of tobacco use predict the number and types of sources accessed.
  
  
  METHODS
  A survey assessing usual sources of cigarettes and related variables was administered to 4461 seventh-graders annually. Of the target population, 79% provided baseline data, and 64.2% participated in all surveys.
  
  
  RESULTS
  At baseline, 30% of the 1144 smokers got cigarettes from peers, compared with 11% using stores, 6% using vending machines, and 17% who stole them. Age of smoking onset did not predict the number or types of sources teens accessed. We did, however, find a significant effect of duration of smoking, showing that more practiced smokers were more likely to get cigarettes both from stores and from their friends. Further, the longer students smoked, the more likely they were to have friends who smoked.
  
  
  CONCLUSIONS
  Our results indicated that the means through which teens got their first cigarettes were similar, regardless of when smoking onset occurred. In contrast, as teens became more established smokers, they increased the number of sources they used and relied more on both stores and peers. Once adolescents become smokers, they form a social network of fellow smokers who support their habit, making it even more difficult to quit.
authors.affiliation: Department of Psychology, The University of Memphis, Memphis, Tennessee 38152-3230, USA. L.Robinson@mail.psyc.memphis.edu
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Robinson
authors.forename: William T
authors.initials: WT
authors.lastname: Dalton
authors.forename: Leslie M
authors.initials: LM
authors.lastname: Nicholson
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000208:ethnology; D017668:Age of Onset; D000704:Analysis of Variance; D005190:Family; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010379:Peer Group; D017678:Sex Distribution; D012907:Smoking / Q000191:economics* / Q000453:epidemiology*; D013714:Tennessee; D014026:Nicotiana