{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T18:04:58Z","timestamp":1790877898109,"version":"4.1.0"},"reference-count":47,"publisher":"BMJ","funder":[{"DOI":"10.13039\/100000026","name":"National Institute on Drug Abuse","doi-asserted-by":"publisher","award":["R21DA058328"],"award-info":[{"award-number":["R21DA058328"]}],"id":[{"id":"10.13039\/100000026","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["Tob Control"],"accepted":{"date-parts":[[2026,9,10]]},"abstract":"<jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>Nicotine concentration is a key characteristic of modern e-cigarette products. This study aims to illuminate age-related differences and temporal trends in nicotine concentrations to help inform strategies to reduce nicotine-related public health risks.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Data were drawn from the US Population Assessment of Tobacco and Health Study Wave 5 (December 2018\u2013November 2019), Wave 6 (March\u2013November 2021) and Wave 7 (January 2022\u2013April 2023) and analysed in 2026. \u03c7\u00b2 tests and multivariable regressions were used to compare nicotine levels used in e-cigarettes (ie, unknown, 0%, 0.1\u20131.7%, 1.8\u20134.9%, 5.0%+) by age groups at Wave 7 and examine trends in nicotine concentrations for adults (18+) across Waves 5\u20137.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Among individuals currently using e-cigarettes at Wave 7 (n=3782), about 60.1% of those aged 12\u201314 and 51.2% of those aged 15\u201317 reported not knowing nicotine concentrations, and young adults aged 18\u201324 were the most likely to report using 5.0%+ (38.7% prevalence vs 24.4% of those aged 25\u201334, 14.6% of 35\u201354 and 4.3% of 55+). The proportion of adults responding \u2018I don\u2019t know\u2019 increased from 15.8% at Wave 5 to 23.8% at Wave 7, especially among those aged 18\u201324 (13.9\u201326.0) and 25\u201334 (13.9\u201323.6%). The proportion of adults reporting 5.0%+ increased from 13.9% to 24.4%(p&lt;0.0001), and those reporting 0.1\u20131.7% decreased from 49.2% to 35.4% (p&lt;0.0001).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Over half of youth using e-cigarettes were unaware of the nicotine concentration. High-concentration products have become increasingly prevalent, especially among young adults. Clearer nicotine concentration labelling on e-cigarette products and continued surveillance of nicotine levels are needed.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/tc-2026-060393","type":"journal-article","created":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T17:25:53Z","timestamp":1790875553000},"page":"tc-2026-060393","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Comparison of e-cigarette nicotine concentrations used by US adults and youth"],"prefix":"10.1136","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1395-7904","authenticated-orcid":false,"given":"Hongying Daisy","family":"Dai","sequence":"first","affiliation":[{"name":"College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-2711-8615","authenticated-orcid":false,"given":"Paula R","family":"Guastello","sequence":"additional","affiliation":[{"name":"College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2026,10,1]]},"reference":[{"key":"2026100110201420000_tc-2026-060393v1.1","first-page":"335","article-title":"E-Cigarettes: Current Evidence and Policy","volume":"114","author":"Lichtenberg","year":"2017","journal-title":"Mo Med"},{"key":"2026100110201420000_tc-2026-060393v1.2","doi-asserted-by":"publisher","DOI":"10.1001\/jama.2019.15331"},{"key":"2026100110201420000_tc-2026-060393v1.3","doi-asserted-by":"crossref","DOI":"10.1186\/s12889-020-09572-x","article-title":"E-cigarettes use in the United States: reasons for use, perceptions, and effects on health","volume":"20","author":"Sapru","year":"2020","journal-title":"BMC Public Health"},{"key":"2026100110201420000_tc-2026-060393v1.4","doi-asserted-by":"publisher","DOI":"10.1093\/jnci\/djab208"},{"key":"2026100110201420000_tc-2026-060393v1.5","doi-asserted-by":"publisher","DOI":"10.1136\/tobaccocontrol-2017-053759"},{"key":"2026100110201420000_tc-2026-060393v1.6","doi-asserted-by":"crossref","DOI":"10.1001\/jamanetworkopen.2021.47891","article-title":"Exposure to Toxicants Associated With Use and Transitions Between Cigarettes, e-Cigarettes, and No Tobacco","volume":"5","author":"Dai","year":"2022","journal-title":"JAMA Netw Open"},{"key":"2026100110201420000_tc-2026-060393v1.7","unstructured":"National Academies of Sciences Engineering and Medicine . 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