Effects of pH/Nicotine, Refill Fluid, Cigarette Type, and Storage on Element/Metal Concentrations in Electronic Cigarette Fluids and Aerosols

The concentrations of metals, acids, nicotine, and flavor chemicals were analyzed in four refill fluids before and after vaping in third-and-fourth-generation electronic cigarettes (ECs), and the effect of storing fluids in ECs on element/metal concentrations was determined. Metals and organic chemicals were analyzed using inductively coupled plasma optical emission spectroscopy, HPLC, and GC/MS. Maleic, benzoic, propionic, and citric acid were the refill fluid (0.032 to 5.498 mg/mL). Nickel, zinc, tin, selenium, silicon, copper, and lead were often in refill fluids before and after heating and in aerosols. Third generation ECs and low pH fluids generally had the highest concentrations of metals in their fluids and aerosols. Thirty flavor chemicals were in at least one refill fluid. During storage, metal concentrations in EC fluids increased significantly by 28 days and increased exponentially over 387 days. After storage, EC fluids with the lowest pH often had the highest concentrations of nickel, zinc, lead, and tin. The acids and increase in metals after heating and storage are a health concern that could contribute to respiratory diseases. These data support the need for providing date-of-manufacture on packaging, regulating acids/metals in ECs, and better understanding of the effects of EC metals/acids on human health.