{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T21:20:58Z","timestamp":1791321658975,"version":"4.3.1"},"reference-count":45,"publisher":"Oxford University Press (OUP)","issue":"9","license":[{"start":{"date-parts":[[2018,9,7]],"date-time":"2018-09-07T00:00:00Z","timestamp":1536278400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/journals\/pages\/open_access\/funder_policies\/chorus\/standard_publication_model"}],"funder":[{"name":"Ministry of Health and Long-Term Care Health System Research Fund","award":["(#06697"],"award-info":[{"award-number":["(#06697"]}]},{"DOI":"10.13039\/501100000024","name":"Canadian Institutes of Health Research","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100000024","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Vanier Canada Graduate Scholarship"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2019,8,19]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Introduction<\/jats:title><jats:p>\u201cDual use\u201d refers to the concurrent use of tobacco cigarettes (smoking) and electronic cigarettes (e-cigarettes; vaping). Although dual use is common among e-cigarette users, there is little evidence regarding biomarkers of exposure among dual users and how these change under different conditions of product use.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>A nonblinded within-subjects crossover experiment was conducted with adult daily dual users (n = 48) in Ontario, Canada. Participants completed three consecutive 7-day periods in which the use of tobacco cigarettes and e-cigarettes was experimentally manipulated, resulting in four study conditions: Dual use, Tobacco cigarette use, E-cigarette use, and No product use. Repeated measures models were used to examine changes in product use and biomarkers of exposure.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Compared to dual use, cotinine remained stable when participants exclusively smoked (p = .524), but significantly decreased when they exclusively vaped (p = .027), despite significant increases in e-cigarette consumption (p = .001). Levels of biomarkers of exposure to toxicants, including carbon monoxide (CO), 1-hydroxypyrene (1-HOP), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), were significantly lower when participants exclusively vaped than when they engaged in dual use (CO = \u221241%, p &lt; .001; 1-HOP = \u221231%, p = .025; NNAL = \u221230%, p = .017). Similar findings were observed among participants abstaining from both products as compared to dual use (CO: \u221226%, p &lt; .001; 1-HOP = \u221214% [ns]; NNAL = \u221235%, p = .016). In contrast, levels of biomarkers of exposure increased when participants exclusively smoked as compared to dual use (CO = +21%, p = .029; 1-HOP = +23%, p = .048; NNAL = +8% [ns]).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>Although dual use may reduce exposure to tobacco smoke constituents to some extent, abstaining from smoking is the most effective way to reduce such exposure.<\/jats:p><\/jats:sec><jats:sec><jats:title>Implications<\/jats:title><jats:p>Public health authorities should clearly communicate the relative risk of e-cigarettes and tobacco cigarettes to the general public, focusing on two salient points: (1) e-cigarettes are not harmless, but they are less harmful than tobacco cigarettes; and (2) using e-cigarettes while smoking may not necessarily reduce health risks; therefore, consumers should stop smoking completely to maximize potential health benefits.<\/jats:p><\/jats:sec>","DOI":"10.1093\/ntr\/nty174","type":"journal-article","created":{"date-parts":[[2018,9,5]],"date-time":"2018-09-05T19:47:00Z","timestamp":1536176820000},"page":"1259-1266","source":"Crossref","is-referenced-by-count":62,"title":["Biomarkers of Exposure Among \u201cDual Users\u201d of Tobacco Cigarettes and Electronic Cigarettes in Canada"],"prefix":"10.1093","volume":"21","author":[{"given":"Christine D","family":"Czoli","sequence":"first","affiliation":[{"name":"School of Public Health and Health Systems, University of Waterloo, Waterloo, ON, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Geoffrey T","family":"Fong","sequence":"additional","affiliation":[{"name":"School of Public Health and Health Systems, University of Waterloo, Waterloo, ON, Canada"},{"name":"Department of Psychology, University of Waterloo, Waterloo, ON, Canada"},{"name":"Ontario Institute for Cancer Research, Toronto, ON, 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