A biomonitoring assessment of secondhand exposures to electronic cigarette emissions

Electronic cigarette (e-cigarette) conventions regularly bring together thousands of users around the world. In these environments, secondhand exposures to high concentrations of e-cigarette emissions are prevalent. Some biomarkers for tobacco smoke exposure may be used to characterize secondhand e-cigarette exposures in such an environment.

Participants who did not use any tobacco product attended four separate e-cigarette events for approximately six hours. Urine and saliva samples were collected from participants prior to the event, immediately after the event, 4-h after the event, and the next morning (first void). Urine samples from 34 participants were analyzed for cotinine, trans-3'-hydroxycotinine, S-(3-hydroxypropyl)-N-acetylcysteine (3-HPMA), S-carboxyethyl-N-acetylcysteine (CEMA), select tobacco-specific nitrosamines (TSNAs), and 8-isoprostane. Saliva samples were analyzed for cotinine and trans-3'-hydroxycotinine.

Data from 28 of 34 participants were used in the data analysis. Creatinine-adjusted urinary cotinine concentrations increased up to 13-fold and peaked 4-h after completed exposure (range of adjusted geometric means [AGMs] = 0.352-2.31 microg/g creatinine). Salivary cotinine concentrations were also the highest 4-h after completed exposure (range of AGMs = 0.0373-0.167 ng/mL). Salivary cotinine and creatinine-corrected concentrations of urinary cotinine, trans-3'-hydroxycotinine, CEMA, and 3-HPMA varied significantly across sampling times. Urinary and salivary cotinine, urinary trans-3'-hydroxycotinine, and urinary 3-HPMA concentrations also varied significantly across events.

Secondhand e-cigarette exposures lasting six hours resulted in significant changes in exposure biomarker concentrations of both nicotine and acrolein but did not change exposure to tobacco-specific nitrosamines. Additional research is needed to understand the relationship between biomarker concentrations and environmental concentrations of toxicants in e-cigarette emissions.