Introduction: Recent studies evidenced that adolescent never-smokers exposed to secondhand tobacco smoke (SHS) endorsed nicotine dependence symptoms. Other studies showed that SHS exposure measured with biomarkers among never-smokers independently predicted withdrawal sensations and prospective smoking initiation. The aim of the present study was to replicate and extend these findings by investigating whether social and pharmacological measures of SHS exposure predicted precursors to smoking among never-smoking adolescents.
Methods: Participants included 327 never-smokers aged 11-15 years attending sixth or seventh grade in French language schools in Montréal, Canada. They completed self-report questionnaires measuring their smoking status, social smoke exposure (number of smokers in their environment and number of situations where SHS exposure occurs), and precursors to smoking initiation (smoking expectancies, perceived nicotine dependence, and smoking susceptibility). Each participant provided a saliva sample from which cotinine biomarkers were derived to measure pharmacological exposure to SHS.
Results: When predictors were modeled individually, number of smokers predicted perceived nicotine dependence (p ≤ .05), smoking susceptibility (p ≤ .001), and expected benefits (p ≤ .05), whereas number of situations predicted smoking susceptibility (p ≤ .01). When predictors were modeled simultaneously, number of smokers predicted perceived nicotine dependence (p ≤ .01), smoking susceptibility (p ≤ .01), and expected benefits (p ≤ .05).
Conclusions: Social smoke exposure was a predictor for smoking precursors. Pharmacological exposure to SHS did not predict smoking precursors, which may be partly attributable to the low cotinine values observed in our sample. Suggestions for improved pharmacological measurement of SHS and implications for public health are discussed.