Background: Youth vaping prevalence varies across countries and may be related to differing regulations/products. The emergence of cheap disposable vapes and high-concentration nicotine salts heightened concerns related to youth's ease of access, dependence and potential health risks.
Objectives: We examined youth in England versus Canada and the United States and: how patterns of vaping/smoking varied, given the countries' different regulatory frameworks nicotine and potential toxicant exposure in youth who vape, smoke or do neither in youth who use salt and free-base nicotine respiratory symptom reporting.
Design, methods, setting and participants: Objectives 1 and 4: Repeated cross-sectional surveys (International Tobacco Control Youth Tobacco and Vaping Surveys), England, Canada, United States, 2017-22, N = 1355-39,214, 16- to 19-year-olds, or 16- to 29-year-olds, depending on analysis. Objectives 2 and 3: International Tobacco Control Biomarker Sub-Study, England, Canada, United States, 2019-22, 16- to 19-year-olds, N = 364 and England-only Biomarker Sub-Study, 2022-3, 16- to 19-year-olds, N = 201. Past-week users and past 30-day non-users were tested.
Interventions: None, comparisons based on vaping/smoking status.
Main outcome measures: Objective 1: Vape flavours, nicotine concentration, product types, brands used. Objectives 2 and 3: Urinary biomarkers, normalised for creatinine; tobacco-specific nitrosamine NNK (NNAL); volatile organic compounds (VOCs): acrolein (3HPMA), acrylamide (2CaHEMA), acrylonitrile (2CyEMA), benzene (PhMA), toluene (BzMA), xylene (24MPhMA); nicotine: cotinine, trans-3'-hydroxycotinine (3-HC), total nicotine equivalents. Objective 4: Self-reporting any of 5 past-week respiratory symptoms (e.g. cough and dyspnoea).
Results: Objective 1: Usual flavours were unchanged after 2020 United States pod-based vape flavour restrictions. Youth used exempt brands/products. Simultaneously, disposable vape use increased. In England, in 2022, 48% of 16- to 29-year-olds who vaped in past 30 days used Elf Bar brands, mainly for subjective responses (e.g. flavour/taste), rather than quitting smoking. Nicotine concentrations varied cross-country. Objectives 1, 2 and 3: Compared to smoking tobacco (exclusive or alongside vaping), exclusive vaping was associated with: similar nicotine exposure (those using nicotine salts had higher levels of nicotine metabolites vs. free-base/unknown); lower exposure to NNK, acrolein, acrylamide and acrylonitrile, but higher toluene exposure (than dual use). Compared with not vaping/smoking, exclusive vaping was associated with similar exposure to acrolein and acrylonitrile and higher exposure to toluene and acrylamide (past 24-hour sensitivity analysis). Benzene and xylene biomarkers were detected in < 5% of urine samples. Some country-level biomarker differences were observed. Objective 4: Vaping was associated with higher respiratory symptom reporting than not vaping/smoking. Youth who smoked and vaped had higher odds of symptoms than those only vaping. Using fruit, multiple or 'other' flavours was associated with higher odds of symptoms than tobacco flavours. Nicotine salt use was frequently unknown but may be associated with symptoms.
Limitations: Recall, misunderstandings and misreporting are possible. A subset of biomarkers was included, not all potential confounders were assessed and categorisation into vaping/smoking groups based on past-week behaviour does not fully account for past smoking exposure.
Conclusions: Pod flavour restrictions were ineffective. Youth were increasingly using disposable vapes containing nicotine salts. Those who vape were exposed to lower levels of toxicants than those who smoke, but a few toxicants were higher compared to youth who did not vape/smoke. Self-reported past-week respiratory symptoms were also higher in those who vaped than those not vaping/smoking and were related to flavours.
Future work: The rapidly evolving nicotine vape market needs ongoing survey/biomarker research.
Funding: This synopsis presents independent research funded by the National Institute for Health and Care Research (NIHR) Public Health Research programme as award number NIHR130292.
Keywords: BIOMARKERS; CARCINOGENS; E-CIGARETTES; HEALTH; NICOTINE; RESPIRATORY SYMPTOMS; SMOKING; TOXICOLOGY; VAPING; YOUTH.
We wanted to learn about youth nicotine vaping: Whether different products are used across countries with different regulations? How much nicotine and substances that could cause harm are in their bodies? Are there links with coughs and other breathing symptoms? We conducted surveys of > 12,000 16- to 19-year-olds at least every year between 2017 and 2022, including over 9500 who vaped in England, Canada or the United States. In the United States, banning flavours in some vaping products was not associated with a change in flavours used, and more youth used disposables not covered by this ban. In England, about half of all who vaped used a specific brand, mainly because of its flavours. Nicotine concentrations in vapes varied across the countries, which is in line with the different regulations. To compare nicotine and harmful substances, we collected and tested urine from over 500 youth in England, Canada and the United States. Youth who vaped had nicotine levels like youth who smoked, but their levels of other substances were often very close to youth who did not vape or smoke. Responses from over 39,000 youth surveyed in 2020 or 2021 showed that symptoms like coughing and shortness of breath were similarly common among youth who vaped and youth who smoked, and these were less common among youth who did neither. Nicotine salts, a form of nicotine, were linked with higher nicotine levels in people’s bodies. Links with breathing symptoms were possible, but many people were unsure about whether nicotine salts were used. Youth who vaped had nicotine levels like youth who smoked, but they had much lower levels of other harmful substances. Youth who vape reported breathing issues. Different products may have different effects. Regulations should consider all product types to achieve their aims.