Formation of Tobacco-Specific Nitrosamines from the Atmospheric Aging of Nicotine
WONSIK WOO, Linhui Tian, Ying-Hsuan Lin, University of California, Riverside
Abstract Number: 240
Working Group: Health-Related Aerosols
Abstract
Secondhand vaping aerosols are a source of environmental nicotine, which can undergo changes in its chemical composition due to aging by atmospheric oxidants and gas-particle partitioning. In places with the greatest amount of nicotine emissions, there tends to also be an abundance of ground-level atmospheric oxidants such as O3 and NOx due to high anthropogenic activity and pollution in urban areas. Having NOx as potential nitrosating agents brings forward the possibility for nicotine to undergo chemical transformation in the atmosphere and form tobacco-specific nitrosamines (TSNAs). This study aims to simulate the atmospheric aging process of nicotine-containing vaping emissions and monitor the formation of TSNAs during this process using mass spectrometry, and assess the genotoxic potential of these aged aerosols via in vitro exposures. Our observations indicated that fresh vaping emissions contained minimal amounts of NNN (N’-nitrosonornicotine) and NNK (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone) in the particle phase. In contrast, O3-mediated and NOx-mediated aging induced significant generation of both TSNAs. NO2 showed the greatest ability to produce NNN during the 3-hour aging process, while NNK is the predominant TSNA produced during O3-mediated aging. BEAS-2B cells will be exposed to both fresh and aged e-cigarette aerosols to determine if the aging process has significant effects on their genotoxicity. Altered expressions of the DNA repair enzymes, MGMT and AAG, will be monitored with qPCR, and the abundance of nuclear DNA damage will be determined with the qPCR-based, LORD-Q assay for the quantification of lesion frequency. This work suggests that the atmospheric oxidation and aging of nicotine produce known carcinogens, highlighting a significant area of concern. The expected results will provide scientific evidence that will aid in bringing awareness to this topic in the hope that future work will be performed to study the chemical and toxicological complexity of aged secondhand tobacco products.