Hidden contaminants in e-liquids: Detection of microplastics and their potential human health risks

The most popular tobacco product is electronic cigarettes (ECs), which are frequently perceived as a safer substitute for cigarette smoke. However, more investigation is necessary to fully understand their chemical makeup, especially with reference to microplastics (MPs), whose potential impact to human health is still unknown. This study aimed to evaluate the presence of microplastics in commercial vaping liquids (ELs) and assess their potential risks to human health. ELs were discharged from their containers, dissolved in bifiltered distilled water and subjected to double oxidation in order to remove organic pollutants. To recover MPs, the solutions were filtered through sieves of varying mesh sizes. A stereomicroscopic screening identified and quantified irregularly shaped particles, while scanning electron microscopy (SEM) revealed their rough, broken edges. MP composition was determined by µFTIR analysis. The most prevalent polymer (40-70 % of all MPs), polypropylene (PP), pointed to EC plastic components as the primary source. Polyethylene terephthalate (PET) accounted for 5-25 %, while polyethylene (PE) and polystyrene (PS) likely originated from additives, each contributed under 10 %. The MP particle counts ranged from 4 to 14 per 10 mL of ELs. A significant health hazard from MP‑laden vapour was computed using a conceptual vaping exposure model that included key environmental toxicology variables, highlighting the critical need for comprehensive exposure evaluation.