Influence of e-Liquid pH on Heavy Metal Emissions in Open-System Electronic Cigarette Aerosols and Associated Health Risks

These findings indicate that e-liquid acidity is a key determinant of metal emissions and metals-attributable cancer risk in open-system electronic cigarettes. While risks remain substantially lower than those associated with combustible smoking, exposures at market-representative pH values can exceed established inhalation thresholds for chromium and produce non-trivial excess lifetime cancer risk. Regulatory frameworks may therefore benefit from considering e-liquid pH, device material compatibility, and routine aerosol metals testing across relevant pH ranges to better align product standards with harm-reduction objectives.