"Safer” ultrasonic vapes feared to be more harmful due to toxic metals

Despite sleek marketing that paints them as safer alternatives, ultrasonic cigarettes—or u-cigarettes—might pose greater health risks than earlier vaping devices. A recent study conducted by scientists at the University of California, Riverside, has found that these next-gen vapes may release toxic metals, including arsenic and selenium, into users' lungs—metals associated with cancer, lung disease, and other serious health conditions.

U-cigarettes differ from traditional e-cigarettes in their mechanism. Instead of using heated coils to produce vapor, an article by SciTechDaily shedding light on the study's findings points out that they rely on a “sonicator”—a high-frequency ultrasonic vibration system—to aerosolize a liquid mixture. This liquid usually contains nicotine, flavorings, and a base such as propylene glycol or vegetable glycerin.

The new study, published in Environmental Health Perspectives journal, examined the chemical and metal content in several u-cigarette products—specifically SURGE u-cigarettes—as well as leading pod-based e-cigarettes like JUUL and other similar models.

“U-cigarettes claim to be less harmful than e-cigarettes,” said Esther Omaiye, a postdoctoral researcher in the Department of Molecular, Cell and Systems Biology and the study’s lead author. “Since this novel technology has limited evidence-based data, we were interested in investigating this claim to understand the chemistry and toxicology involved and the potential impact on user behavior.”

Using advanced techniques such as scanning electron microscopy and optical emission spectroscopy, the researchers detected 16 different elements in either the liquid or vapor samples of the products studied.

“We found u-cigarette fluids and aerosols generally had higher concentrations of metals compared to fourth-generation e-cigarettes,” Omaiye explained. “Metals in u-cigarettes are not essential for the functioning of the device. However, they are usually present as unintended contaminants. Their presence is a health concern.”

Among the metals detected were silicon and nickel. While nickel appeared in low concentrations across most products, one device—the KWIT Stick—contained up to 66,050 micrograms per milliliter of e-fluid, a significantly high amount. SURGE products also contained copper and zinc, though these metals showed minimal transfer to the aerosol inhaled by users.

“The most concerning results were the elevated levels of arsenic and selenium in SURGE products, both of which are listed on the FDA’s Harmful and Potentially Harmful Constituents List,” said Prue Talbot, senior author of the study and a professor in the graduate division. “Our study underscores the urgent need for regulations to limit arsenic and selenium in these products and calls for routine surveillance to identify rogue products with abnormally high metal levels.”

Both Talbot and Omaiye stress the potential long-term health consequences of using u-cigarettes, which may include cancer, organ damage, and neurotoxicity. Inhaling metals such as arsenic, nickel, and selenium can also lead to severe respiratory diseases, including silicosis and metal fume fever.

According to the researchers, the findings make a strong case for continued independent evaluations of vaping technologies, especially as new designs and materials enter the market. Omaiye noted that examining how devices are constructed—and what they’re made of—is key to understanding and mitigating health risks.

“Stricter manufacturing regulations and accountability are needed to ensure the safety of device components and vaping liquids,” she said. “Medical professionals, regulatory agencies, and the public must stay informed and proactive as new vaping technologies emerge, recognizing that changes in components may not eliminate health risks.”

By Nazrin Sadigova