Parental smoking and smoking experimentation in childhood increase the risk of being a smoker 20 years later: the Childhood Determinants of Adult Health Study.

AIMS: To examine the long-term effects of childhood smoking experimentation and exposure to parental smoking on adult smoking risk. METHODS: Data were from a 20-year follow-up of 9-15-year-olds who completed questionnaires in the 1985 Australian Schools Health and Fitness Survey (n=6559). The relative risks (RR) of adult current smoking in 2004-05 for childhood exposure to smoking experimentation (never, a few puffs, <10 cigarettes, >10 cigarettes) and parental smoking (none, father, mother, both parents) in 1985, with adjustment for confounders, were estimated by log binomial modelling. Analyses were stratified by age (9-13 and 14-15 years) and sex. FINDINGS: Participation at follow-up was 54% (n=3559). Childhood smoking experimentation increased the risk of being a current smoker particularly for 14-15-year-old experimenters of more than 10 cigarettes [males, RR 2.72, 95% confidence interval (CI) 1.74-4.25; females, RR 6.39, 95% CI 2.85-14.33]. Parental smoking was associated with adult current smoking risk, particularly for 9-13-year-olds with two smoking parents (males, RR 1.53, 95% CI 1.19-1.96; females, RR 1.99, 95% CI 1.52-2.61) and older males with smoking mothers (RR 1.82, 95% CI 1.22-2.73). Parental smoking was not associated with childhood smoking experimentation. CONCLUSIONS: These findings suggest that any childhood smoking experimentation increases the risk of being a smoker 20 years later. As exposure to parental smoking predicted current smoking, parents should be aware of the association between their own smoking behaviour and that of their children.