Estimating the human health risks associated with exposures to harmful constituents emitted from electronic cigarettes
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Son, Yeongkwon.
Estimating the human health risks associated with exposures to harmful constituents emitted from electronic cigarettes. Retrieved from
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TitleEstimating the human health risks associated with exposures to harmful constituents emitted from electronic cigarettes
Date Created2018
Other Date2018-01 (degree)
Extent1 online resource (xvii, 187 p. : ill.)
DescriptionThe use of electronic cigarettes (e-cigarettes) has been rapidly increased because e-cigarettes are believed to be less harmful to health than conventional cigarettes. In the past five years, a few human and rodent in vivo and in vitro studies have suggested adverse health effects associated with e-cigarette vaping. However, the emission of chemicals and particles from e-cigarettes is still not well understood under “real-world” vaping conditions. This study evaluated the impacts of “real-world” e-cigarette battery power outputs, vaping topographies, and e-liquid compositions on e-cigarette particle size distribution, e-vapor chemical composition, and the vaping-induced human cancer risk. E-vapors were generated using a smoking machine under various e-cigarette power settings, vaping topographies, and e-liquid compositions. These e-vapor generation conditions reflected the “real-world” e-cigarettes use pattern, and were obtained from the literature and a panel of 23 current e-cigarette users. E-cigarette particle size distributions (10 nm - 5 m) were measured with a portable aerosol mobility spectrometer and an optical particle counter. E-cigarette particle deposition patterns in human airways were estimated using the Multiple-Path Particle Dosimetry (MPPD) Model. Harmful constitutes in e-vapor were characterized for nicotine and nicotyrine (ultraviolet–visible (UV) spectroscopy), hydroxyl radical (UV fluorescence), and carbonyls (high performance liquid chromatography (HPLC)-UV detection). Human cancer risks associated with e-cigarette vaping were also estimated using Monte Carlo simulations. The count median diameter (CMD) of e-cigarette particles ranged from 116 to 280. The CMD increased by 46%, when the heating power increased from 6.4 watts to 31.3 watts. The CMD of the particles generated from the vegetable glycerin (VG)-based e-liquid was 44% larger than the CMD of the particles generated from propylene glycol (PG)-based e-liquids. Both longer puff duration and smaller puff volume facilitated the formation of bigger e-cigarette particles. This study, for the first time, discovered that e-cigarette particle measurement results are substantially influenced by measurement temperature and humidity. The amount of nicotine generated from e-cigarette vaping (ranging from 0.37 µg to 249.02 µg per puff) was comparable to cigarette smoking, especially under high e-cigarette power output, large puff volume, and high e-liquid nicotine levels. E-cigarette coil temperature favored the formation of nicotiyrine, the concentration of which in e-vapor were substantially higher than that in cigarette smoke (55-222 ng per puff for e-cigarette vs. 2-13 ng per puff for cigarette). Higher e-cigarette power and larger puff volume facilitated the formation of hydroxyl radical in e-vapor. An increase in power output and puff volume resulted in significantly higher levels of •OH formation in e-vapor due to the elevated coil temperature and oxygen supply. VG-based e-liquids generated higher amount of •OH than PG-based e-liquids. Furthermore, e-vapor could induce •OH formation, and the co-exposure to transition metal ions accelerated •OH formation. Flavored e-liquids generated larger amount of •OH in e-vapor than non-flavored e-liquids. Compared with VG-based e-liquid, PG-based e-liquids increased formaldehyde and acetaldehyde emission by 2 - 12 folds. Other potentially harmful chemicals were also identified in e-vapor, including glyoxal, acrolein, diacetyl and acetylpropionyl. An increase in device power output from 6.4 watts to 31.3 watts resulted in the increase in formaldehyde emission by 39.3% (1257.8 ug per puff) and 142.1% (2318.2 ug per puff) for VG and PG e-liquid, respectively. PG-based e-liquid generated higher levels of formaldehyde and acetaldehyde than VG-based e-liquid by a factor of 2 and 12, respectively. In addition, glyoxal and acrolein were detected in e-vapor under high power output conditions. Other potentially harmful carbonyls or their precursors, including diacetyl, acetylpropionyl and acetoin, were observed in e-vapor generated from flavored e-liquids. Cancer risks associated with e-cigarette vaping ranged from 9.55×106 to 7.51×104, mainly contributed by carbonyls. Vaping under 31.3 watts posed a 2 -3 times higher cancer risk than vaping under 6.4 watts. PG and PG&VG mixture based e-liquids induced 3.9 and 2.3 folds higher cancer risks than VG-based e-liquids. In contrast, if the cancer risks were normalized by e-vapor nicotine concentrations, vaping under 14.7 watts and 31.3 watts posed 7 - 10 folds smaller cancer risks than vaping under 6.4 watts.
NotePh.D.
NoteIncludes bibliographical references
Noteby Yeongkwon Son
Genretheses, ETD doctoral
Languageeng
CollectionSchool of Graduate Studies Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.
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