Junhan Cho

Background ZYN brand and non-tobacco-flavoured products capture most of the US nicotine pouch market. Evidence of which nicotine pouch flavours and brands US youth use is critical for informing youth regulatory protections, but currently lacking. Methods We analysed data from adolescents reporting lifetime nicotine pouch use in the 2025 Monitoring the Future study, a nationally representative, in-school, cross-sectional annual survey of US 8th-grade, 10th-grade and 12th-grade students. Prevalences of nicotine pouch flavours and brands adolescents reported using most often were estimated in the overall sample and stratified by demographic characteristics and past-30-day pouch use patterns. Results Among 472 youth who used nicotine pouches in their lifetime, 97.0% (95% CI 94.6% to 98.4%) reported using nicotine pouches with a non-tobacco flavour most often; non-tobacco flavoured pouch use prevalence exceeded 93% across all demographic and past-30-day pouch use-frequency categories studied. Mint was the most commonly reported flavour used (58.6%), followed by fruit (16.0%); use of original/unflavoured pouches was rare (3.0%). ZYN was the most common brand used, reported by 79.7% (95% CI 74.1% to 84.4%) of youth. Use prevalence of ZYN versus other pouch brands was lower among non-Hispanic Black versus non-Hispanic White, but did not vary by sex, grade, population density or pouch use frequency. Conclusions Among US adolescents reporting lifetime use of nicotine pouches in 2025, use of non-tobacco flavoured pouch products was nearly universal and ZYN was the predominant brand used. Prioritising regulatory policies on flavoured pouches, especially ZYN brand products, merits consideration to reduce youth nicotine pouch use.

Responses to social stressors are important drivers of cancer risk and outcomes; however, current studies focus on neighborhood-level social determinants of health (SDOH). We evaluated within-subject trajectories in stress reactivity (i.e., change in salivary cortisol) among 60 African American patients with breast cancer and examined the moderating effects of social stressors on cortisol responses. SDOHs were obtained by self-report and were included in linear mixed-effects regression models that were generated for cortisol levels, including time (primary regressor) adjusting for time-invariant covariates. Significant increases in cortisol levels were observed at 12- and 24-minute post-Trier Social Stress Test tasks. Significant interactions between time and SDOHs on cortisol were identified. Higher and escalating stress reactivity was observed in patients with greater financial strain, social isolation, negative life events, and perceived stress. Social risk factors moderated stress reactivity; however, additional research is needed to understand the effects of physiologic stress reactivity on tumor etiology and progression, especially among patients who have greater exposure to social stressors.Significance:Chronic stress exposure promotes breast cancer initiation and progression; however, current studies focus on neighborhood-level deprivation even though individual variability in stress reactivity is an important driver of cancer risk and outcomes, especially among those who experience the greatest burden of disease. Self-reported data on social risk factors can be used to enhance the precision of cancer care by identifying patients who should be prioritized for referral to socially informed care and who are likely to experience dysregulated cortisol response to SDOHs.

Characteristics of study participantsa.

Associations between assessment time points and cortisol levelsa.

Table 3 from Examining the Intersection between Drivers of Disparities: Social Determinants and Stress Reactivity in African American Breast Cancer Survivors

Summary of supplemental cortisol reactivity indices (AUCi, Peak cortisol, and ΔCortisol) by chronic stress exposures

Process model of study procedures

Interaction effects test for log-transformed cortisol levels

Associations between covariates and cortisol levels