Methods: Researchers conducted a systematic review covering published literature up to September 2025. They screened 14,026 articles, assessed 325 full-text articles and included 81 studies.
Findings: Vaping was associated with evidence of harm across eight areas: respiratory health, mental health, cigarette-smoking initiation, oral and dental health, allergies, sleep, ocular symptoms and perinatal outcomes following exposure during pregnancy.
Most consistent findings: Large cross-sectional studies repeatedly reported associations with cough, wheeze, bronchitic symptoms, anxiety, depression and panic disorder.
Conclusion: The authors conclude that current evidence shows important short- and medium-term adverse consequences, while long-term effects remain uncertain.
Overview: This review combines mechanistic, biomarker, preclinical and clinical evidence about cardiovascular effects from nicotine-containing products.
Products considered: The review discusses conventional cigarettes as well as e-cigarettes, heated tobacco products and oral nicotine products.
Findings: Nicotine is linked with sympathetic activation, cardiovascular stress, oxidative imbalance, inflammation and impaired blood-vessel function. Human studies show adverse vascular responses across nicotine-containing products.
Conclusion: Eliminating combustion can reduce vascular toxicity, but according to the review it does not eliminate cardiovascular harm. Long-term outcome data for newer products remain limited.
Purpose: The study compared microplastics derived from conventional cigarette butts and heated tobacco devices and examined the effect of UV-induced aging.
Findings: UV aging reduced nicotine below detection limits, while elemental composition was largely unchanged. Some heated-tobacco cellulose acetate particles fragmented into smaller sizes.
Toxicity testing: No significant effects were found in the tested Daphnia magna, Lemna minor, Tetrahymena thermophila or A549 human lung cell models at the study conditions.
Conclusion: UV aging did not change the measured toxicological profile, but cigarette-butt-derived microplastics remain chemically complex and may vary between products.
Publication type: This is a Letter to the Editor by Christopher Junker.
Position presented: The title states that the author does not believe the current evidence supports classifying e-cigarettes as likely carcinogenic to humans.
Source context: PubMed lists the author's affiliation as the Department of Life Sciences, British American Tobacco, United Kingdom.
Limitation: No abstract is available on PubMed, so this explainer does not add detailed claims that cannot be verified from the available record.
Publication type: This is a Letter to the Editor by Bernard W Stewart, affiliated with the Discipline of Paediatrics and Child Health at the University of New South Wales.
Available information: PubMed provides the title, author, publication details and DOI but no abstract.
Important limitation: Because no abstract is available, this explainer does not attempt to reconstruct or add arguments that are not provided in the PubMed record.
Purpose: The study examined analytical methods for determining the origin of partially identified chemicals found during long-term e-liquid storage.
Methods: Five data-deficient compounds detected after 12 months of room-temperature storage in a JUUL2 pod were investigated. Researchers also artificially aged the same type of e-liquid outside the pod and used isotopically labelled ingredients.
Findings: All five compounds also appeared in e-liquid aged outside the pod. Four were linked to nicotine and one to benzoic acid.
Source context: The listed authors are affiliated with JUUL Labs. The study focuses on analytical identification and does not establish the health effects of these compounds.
Overview: This JAMA Healthy Dialogue discusses the origins of glucagon-like peptide-1, or GLP-1, and the development of GLP-1 receptor agonist medicines. The discussion includes Jens Juul Holst, one of the scientists involved in the discovery of GLP-1, and Lotte Bjerre Knudsen, who played a major role in developing GLP-1 medicines.
Development: Research into gut hormones showed that GLP-1 influences insulin secretion, blood glucose and appetite. Scientists later developed longer-lasting GLP-1 medicines, leading to treatments for type 2 diabetes and obesity.
Health impact: GLP-1 receptor agonists can improve blood sugar control, reduce appetite and support weight loss. Evidence also points to benefits for cardiovascular and kidney health.
Challenges: The discussion highlights possible adverse effects, high costs, unequal access and uncertainty about some long-term consequences.
Conclusion: GLP-1 medicines have major potential for diabetes and obesity care, but medicines alone are unlikely to solve the obesity epidemic. Broader changes involving nutrition, physical activity, health education and inequality are also needed.
Methods: Researchers surveyed 673 female college students who were current smokers from 30 universities in China.
Results: Greater physical activity was associated with lower nicotine dependence. Smoking-refusal self-efficacy and smoker identity were identified as possible indirect pathways in this relationship.
Conclusion: The findings provide preliminary evidence of an association, but longitudinal research is needed to establish causality.