New nicotine and tobacco products and risk of major diseases: A review of the scientific evidence

The use of new tobacco and nicotine products, including e-cigarettes, heated tobacco products (HTPs) and tobacco-free snus (white snus), is rising, especially among adolescents and young adults. However, evidence on their long-term health effects is limited. This review assesses current knowledge on the health risks of these products, with a focus on asthma and allergic diseases, cancer, cardiovascular disease, diabetes, lung disease and pregnancy outcomes.E-cigarettes are associated with increased risks of asthma, respiratory symptoms, chronic bronchitis and chronic obstructive pulmonary disease (COPD). Associations with cardiovascular disease, type 2 diabetes, cancer and adverse pregnancy outcomes are supported by limited epidemiological and experimental data. Less evidence is available on health risks associated with HTPs, but a few epidemiological studies indicate increased risks of asthma and COPD, with supporting data from experimental studies. Evidence on white snus is notably lacking across the different health outcomes. Given its high nicotine content - similar to or higher than in brown snus - it is plausible that white snus increases risks of diabetes, pregnancy complications and other nicotine-related health effects. Methodological limitations of existing epidemiological studies include reliance on self-reported data, inadequate adjustment for cigarette smoking, cross-sectional design and/or short follow up. Future research should prioritize large-scale, longitudinal studies assessing dose, duration and product formulation, including second-hand and prenatal exposure, as well as mechanistic studies. There is an urgent need to elucidate the health impacts of the new nicotine and tobacco products, which are growing in popularity, to inform policy, regulation and public health strategies.