LAUSR

Background Most smokers take up their habit in adolescence. Risk factors for smoking are changing over time as demographics shift, and technologies such as social media create new avenues for the tobacco industry to recruit smokers. We assessed risk factors associated with smoking uptake among a representative cohort of UK adolescents. Methods Data come from 8,944 children followed prospectively as part of the UK Millennium Cohort Study. Smoking uptake was assessed as adolescents who had never smoked tobacco at age 14, but reported smoking [≥]1 cigarette per week by age 17 (regular smoking). We used logistic regression to assess associations between smoking uptake and selected socio-demographic factors including household income, caregiver smoking, peer smoking, and social media use. Weighted percentages and Office for National Statistics Data were used to estimate numbers of regular smokers and new smokers in the UK. Results Among the whole sample, 10.6% of adolescents were regular smokers at age 17. Of these, 52% had started smoking between ages 14 and 17. Uptake was more common if caregivers (14.7% vs 5.7%, p<0.001) or friends smoked (13.0% vs. 5.1%, p<0.001), and among those reporting >5hours/day of social media use (10.0% vs 5.2%, p=0.006). Applying these percentages to population data, an estimated 160,000 adolescents in the UK were regular smokers by age 17, of whom more than 100,000 took up the habit between ages 14 and 17. Discussion Smoking behaviour remains highly transmissible within families and peer groups, reinforcing inequalities. Social media are highlighted as a potential vector.