A University of California, Riverside study has detected harmful metals in the fluid and vapour of ultrasonic cigarettes, raising concerns about the safety of various alternatives to traditional e-cigarettes.
Study Challenges Safety Claims Made by U-Cigarette Manufacturers
The findings, published in Environmental Health Perspectives, raise alarm over the health implications of inhaling metal-contaminated vapour.
“U-cigarettes claim to be less harmful than e-cigarettes,” said Esther Omaiye, the study’s lead author and a postdoctoral researcher. “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 behaviour.”
Ultrasonic Vape Technology
U-cigarettes use high-frequency ultrasonic vibrations to aerosolise a solution typically composed of nicotine, flavourings, and carriers like propylene glycol or vegetable glycerin—unlike conventional e-cigarettes that rely on heated coils to vaporise liquid. This no-heat approach is marketed as a safer, more innovative vaping method.
One popular product studied was the SURGE ultrasonic pod-style e-cigarette, which exemplifies how these devices aim to differentiate themselves in a saturated market. But researchers say the claims of safety may be misleading.
Chemical Analysis Reveals Elevated Metal Levels in U-Cigarettes
Scientists conducted in-depth chemical analysis using scanning electron microscopy and inductively coupled plasma optical emission spectroscopy to investigate the safety of u-cigarettes. Their goal was to compare metal content in u-cigarettes with traditional devices like the JUUL.
“We found u-cigarette fluids and aerosols generally had higher concentrations of metals compared to fourth-generation e-cigarettes,” said Omaiye. “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.”
A total of 16 elements were detected in at least one fluid or aerosol sample. Notably, the SURGE device was found to contain silicon, copper, and zinc. Nickel, though low in most products, spiked to alarming levels—up to 66,050 micrograms per millilitre—in one KWIT Stick sample.
“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 senior author Prue Talbot.
Health Impacts of Inhaling Metal-Contaminated Vapour
Researchers warned that inhaling these metals can lead to serious health issues such as lung diseases (including silicosis and metal fume fever), organ damage, and cancers. Even essential elements like zinc and selenium can be toxic when inhaled in large amounts.
“Even metals like zinc and selenium, essential for life in small amounts, can become toxic at high levels,” said Omaiye. “As fine particles or aerosols, these elements can bypass body defences and reach deep into lung tissues.”
Talbot echoed the urgency, warning that the mode of exposure makes vaping particularly dangerous.
“Regardless of the vaping technology, inhalation of metals like arsenic, nickel, lead, or chromium is always hazardous—even at low concentrations over time,” she said.
Call for Regulation and Industry Accountability
The researchers are calling for immediate action in the form of stricter manufacturing oversight, routine surveillance of new vaping products, and public education on the risks.
“Medical professionals, regulatory agencies, and the public must stay informed and proactive as new vaping technologies emerge,” Omaiye said. “Stricter manufacturing regulations and accountability are needed to ensure the safety of device components and vaping liquids.”
The team plans further investigation into device materials, user behaviour, and long-term effects.
The research was backed by the National Institutes of Health, California’s Tobacco-Related Disease Research Program, and UC Riverside. The study is titled “Quantification of 16 Metals in Fluids and Aerosols from Ultrasonic Pod-Style Cigarettes and Comparison to Electronic Cigarettes.”