Nicotine Dependence in a Banned Market: Biomarker Evidence from E-Cigarette Users in São Paulo, Brazil

Although electronic cigarettes have been banned in Brazil since 2009, their use is increasing, particularly among youth. We conducted a biomarker-based study to profile exclusive e-cigarette users in São Paulo and examine associations with salivary nicotine and cotinine levels. Population-based, cross-sectional study conducted between April and September 2024 in six municipalities in São Paulo, Brazil. Random subjects who reported exclusive use of electronic cigarette completed a questionnaire and provided oral fluid samples for determination of nicotine and cotinine concentrations using LC-MS/MS. The cohort consisted of N=417 participants. Significant associations were found between nicotine and cotinine concentrations and variables such as knowledge of nicotine content and product type. Addiction status significantly influenced nicotine and cotinine concentrations, as well as smoking history, last consumption, recharge/purchase frequency, and consumption duration (all p<0.001). Participants who perceived moderate or severe addiction exhibited higher nicotine and cotinine concentrations compared to those without a perception of dependence (p<0.001). Most participants were young, predominantly White, highly educated and with elevated incomes. Findings revealed a correlation between perceived nicotine dependence and salivary nicotine and cotinine concentrations, underscoring the physiological and behavioral markers of electronic cigarette addiction. High salivary concentrations of nicotine appear to be independent of duration of e-cigarette use, smoking history, and age. These findings underscore the urgent need for surveillance and public health interventions, even in jurisdictions where these products remain illegal. Limitations include cross-sectional design and potential selection bias due to convenience sampling.