Quantification of 16 Metals in Fluids and Aerosols from Ultrasonic Pod-Style Cigarettes and Comparison to Electronic Cigarettes.

BACKGROUND Electronic cigarette (e-cigarette) liquids and aerosols contain metals, which can be detrimental to human health. Recently marketed ultrasonic cigarettes (u-cigarettes) claim to be less harmful than e-cigarettes that use heating coils. OBJECTIVES We quantified chemical elements/metals in multiple flavors of SURGE u-cigarettes, JUUL e-cigarettes, and "Other Brands" of pod-style e-cigarettes. METHODS Elements/metals were identified in atomizers of SURGE using a scanning electron microscope/energy-dispersive X-ray spectrometer. Quantitation of elements/metals in fluids and aerosols from SURGE, JUUL and Other Brands was performed using inductively coupled plasma optical emission spectroscopy. RESULTS U-cigarettes contained a sonicator, unlike e-cigarettes which had heated coils. Sixteen elements were identified in at least one fluid or aerosol sample. Generally, u-cigarette fluids and aerosols had more elements/metals at higher concentrations than aerosols from 4th generation e-cigarettes. Element concentrations generally increased in fluids after vaping. All products, including SURGE, had silicon in their fluids and aerosols. Nickel, which was present in low concentrations in all fluids except KWIT Stick (up to 66,050 μg/mL), transferred to the aerosols with low efficiency. SURGE, but not e-cigarettes, also had copper and zinc in their fluids, but little transferred to their aerosols. SURGE fluids and aerosols, unlike e-cigarettes, had relatively high concentrations of arsenic and selenium. Arsenic and selenium, which are on the FDA's Harmful and Potentially Harmful List, likely came from poor quality solvents used to produce the e-liquids in SURGE pods and possibly from the sonicator, which heats during use. DISCUSSION SURGE u-cigarettes produce aerosols with metals equivalent to heated coil-style e-cigarettes and had high levels of arsenic and selenium, which are a health concern. Regulations limiting arsenic and selenium in these products are needed, and routine surveillance to identify rogue products, such as Kwit Stick, that have abnormally high levels of nickel or other metals could protect human health. https://doi.org/10.1289/EHP15648.