Introduction:
Over the last few years, the increasing use of electronic cigarettes has become a new public health problem. Since 2011, Argentina has had a complete ban on marketing and sale of e-cigarettes. However, e-cigarettes are marketed online and can be easily bought in stores. We conducted a longitudinal study to evaluate the determinants of e-cigarette trial among Argentinean early adolescents.

Methods:
A school-based longitudinal study was conducted in 2014-15, in 3 large cities in Argentina. Among students who reported never smoking an e-cigarette at baseline, we assessed demographics, media use, sensation seeking, smoking behavior, network member smoking, use of other substances, and perception of e-cigarette risk as potential risk factors for e-cigarette trial at follow up (mean between-wave interval 17.1 months) using multilevel logistic regression models with random intercepts for schools.

Results:
E-cigarette trial prevalence increased from baseline (1.8%; n=57) to follow up (7.1%; n=139). Independent predictors of e-cigarette use at follow up included: higher sensation seeking (OR: 1.49 95% CI 1.21-1.84); being a current smoker (OR: 2.58 95% CI 1.38-4.83); having close friends that smoke cigarettes (OR: 1.93 95% CI 1.25-2.99) and being highly exposed to tobacco product ads online (OR: 1.87 95% CI 1.04-3.36). Attending a public school was the only protective factor (OR: 0.40 95% CI 0.22-0.73).

Conclusions:
In Argentina, illicit trial of e-cigarettes among early adolescents is low but appears to be rapidly increasing. Identifying students at risk could help identify policies and programs to prevent increasing use in this population.