{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T11:48:15Z","timestamp":1782301695196,"version":"3.54.5"},"reference-count":38,"publisher":"Oxford University Press (OUP)","issue":"7","funder":[{"name":"analytical chemistry resource","award":["P30DA012393 and S10RR026437"],"award-info":[{"award-number":["P30DA012393 and S10RR026437"]}]},{"name":"NCI and FDA Center for Tobacco Products","award":["R01CA190025-01"],"award-info":[{"award-number":["R01CA190025-01"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,6,23]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Cotinine (nicotine exposure) and cyanoethyl mercapturic acid (2CyEMA, smoke exposure) are known biomarkers for classifying tobacco use status. The increasing use of multiple tobacco products, including dual use of e-cigarettes and cigarettes, drives the need for the assessment of these biomarkers, both individually and in combination to distinguish various product use groups.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We evaluated the 2CyEMA-to-cotinine ratio of urine samples as a metric for differentiating tobacco use status (cigarettes only, e-cigarette only, and dual use) in participants from the Exhale study. Tobacco use status was determined from questionnaire data of participant\u2019s product use in the 48\u00a0hours prior to urine collection. Descriptive statistics and linear regression modeling were used to determine which measures (2CyEMA-to-cotinine ratio or the individual components) could distinguish the different tobacco use patterns.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Compared to the dual use reference group, the 2CyEMA-to-cotinine ratio differentiated cigarettes only (p=.0332) and e-cigarette only (p&amp;lt;.0001) use statuses. Cotinine was not able to distinguish any of the three use statuses and 2CyEMA was only able to differentiate the e-cigarette only users. The 2CyEMA-to-cotinine ratio remains relatively constant across a wide range of smoking frequency, underscoring the efficacy of this smoking metric compared with 2CyEMA or cotinine alone.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>The 2CyEMA-to-cotinine ratio is an effective measure for classifying tobacco use status among cigarette only, e-cigarette only, and dual use users.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Implications<\/jats:title>\n                    <jats:p>The novel approach of examining the 2CyEMA-to-cotinine ratio can serve as a potential measure to distinguish between cigarette only users, e-cigarette only users, and cigarette and e-cigarette dual users.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1093\/ntr\/ntaf201","type":"journal-article","created":{"date-parts":[[2025,9,26]],"date-time":"2025-09-26T12:12:09Z","timestamp":1758888729000},"page":"1103-1110","source":"Crossref","is-referenced-by-count":0,"title":["Assessing the Urinary Cyanoethyl Mercapturic Acid to Cotinine Ratio for Classifying Tobacco Use Status in a Longitudinal Cohort of Cigarette, e-Cigarette, and Dual Users"],"prefix":"10.1093","volume":"28","author":[{"given":"Alma","family":"Nieto","sequence":"first","affiliation":[{"name":"Centers for Disease Control and Prevention, Division of Laboratory Sciences, Tobacco and Volatiles Branch , 4770 Buford Highway, Atlanta, GA 30341 ,","place":["USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Can","family":"Zhang","sequence":"additional","affiliation":[{"name":"Centers for Disease Control and Prevention, Division of Laboratory Sciences, Tobacco and Volatiles Branch , 4770 Buford Highway, Atlanta, GA 30341 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