{"doi":"10.1093/ntr/ntab007","title":"Adolescents and Young Adults Have Difficulty Understanding Nicotine Concentration Labels on Vaping Products Presented as mg/mL and Percent Nicotine","abstract":"INTRODUCTION: E-cigarette e-liquid nicotine concentrations typically are labeled as mg/mL or percent nicotine. We examined whether these metrics accurately convey nicotine strength to young e-cigarette users and if youth can compare concentrations presented in mg/mL and percent nicotine. AIMS AND METHODS: Eight hundred and twenty-one adolescent and young adult e-cigarette users participated in the survey. Participants rated nicotine concentration strengths presented as mg/mL (0-60 mg/mL) and percent nicotine (0%-6%) from \"no nicotine\" to \"very high nicotine.\" Participants also viewed pairs of nicotine concentrations (eg, 18 mg/mL vs. 5%) and indicated which concentration was stronger or if the concentrations were equivalent. RESULTS: On average, participants correctly identified 5.92 (2.68) of 18 nicotine strengths, correctly identifying strengths labeled as mg/mL (3.47 [2.03]) more often than percent nicotine (2.45 [1.38], p < .001). Excluding nicotine-free, participants rated concentrations presented as mg/mL as stronger, more addictive, and more harmful than equivalent concentrations presented as percent nicotine. Participants seldom correctly identified that one concentration was stronger or that both were equivalent (7.58 [5.88] of 19 pairings), although they more often correctly identified the stronger concentration when it was presented in mg/mL (4.02 [SD = 3.01]) than in percent nicotine (2.53 [2.73], p < .001). The most consistent predictor of correct answers on these tasks was familiarity with using both products labeled as mg/mL and labeled as percent nicotine. CONCLUSIONS: Young e-cigarette users had difficulty understanding nicotine concentrations labeled using the most common metrics, raising concerns about inadvertent exposure to high nicotine levels and suggesting that a more intuitive labeling approach is needed. IMPLICATIONS: This study extends prior work showing that young e-cigarette users often are uncertain whether the e-liquids they use contain nicotine by demonstrating that adolescents and young adults have difficulty understanding nicotine concentrations labeled using the two most common metrics (mg/mL and percent nicotine). Errors generally underestimated nicotine strength, and users were not able to accurately compare nicotine concentrations presented as mg/mL and percent nicotine. Difficulty understanding labeling metrics persisted even after accounting for user characteristics like age and vaping experience, suggesting that a novel, easy to understand labeling system is needed to convey information about nicotine strength accurately.","journal":"Nicotine & Tobacco Research","year":2021,"id":169009,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":29,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9307,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":345090,"name":"Thomas Eissenberg","orcid":"0000-0002-8277-5437","position":2,"is_corresponding":false},{"id":304694,"name":"Cristine D. Delnevo","orcid":"0000-0001-9597-4307","position":3,"is_corresponding":false},{"id":383850,"name":"Suchitra Krishnan‐Sarin","orcid":"0000-0002-3272-9782","position":4,"is_corresponding":false},{"id":310224,"name":"Olivia A Wackowski","orcid":"0000-0001-9159-5473","position":0,"is_corresponding":true}],"reference_count":22,"raw_metadata":null,"created_at":"2026-07-18T23:46:11.334362Z","pmid":"33433626","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}