Biomarkers of secondhand smoke and vaping exposure among U.S. Adolescents.

Background: Despite reductions in smoking use among adults and adolescents, e-cigarette use has increased, raising a new public health concern.

Methods: We analyzed Wave 4 (2016-2018) data from the Population Assessment of Tobacco and Health (PATH) Study to assess biomarkers of exposure to secondhand smoke and vaping aerosols among U.S. adolescents (age range 12-17). Participants with no current tobacco use in the past 30 days were divided into four mutually exclusive groups: no exposure, exposure to secondhand smoke (SHS) only, exposure to secondhand aerosol (SHA) only, and dual exposure to both (SHD).

Results: Among 2,379 adolescents (mean[SD] of age = 14.4[0.02]), 1.5 % reported SHA, 18.3 % reported SHS, and 2.8 % reported SHD. Mean concentrations of cotinine were significantly higher among those exposed to SHA only (0.5 ng/mg creatinine, p = 0.04), SHS (3.0,p < 0.0001), or SHD (2.5,p < 0.0001) than among those with no exposure (0.2). As compared to the no-exposure group, both SHS and SHD groups also had higher mean concentrations of carcinogen, NNAL (4.1 and 2.8 pg/mg creatinine, respectively, vs. 0.9, p < 0.0001) and exposure to SHS had a higher level of CYMA (1.8 vs. 1.1 ng/mg creatinine, p < 0.0001). In comparison with the SHA group, the SHS and SHD groups had 6.8 and 3.6 times higher levels of cotinine and 4.6 and 2.2 times higher levels of NNAL, respectively; the SHS group also had higher levels of AAMA and CYMA.

Conclusions: Secondhand vaping aerosol poses a lower exposure risk to youth non-tobacco users than combustible cigarette smoke. The distinct exposure patterns emphasize the importance of implementing tobacco-free policies to reduce youth exposure to environments where combustible tobacco or e-cigarette use occurs.