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They may be smaller than their refillable counterparts, but some disposable e-cigarettes actually emit more toxic metals than older vapes and traditional cigarettes, according to a new study from the University of California, Davis, published in the journal ACS Central Science.
Disposable e-cigarettes are the newest nicotine delivery systems on the market, and the most popular — particularly among adolescents, the Centers for Disease Control and Protection (CDC) reported in 2024. Unlike traditional vapes, which are refilled with pods, disposable e-cigarettes come pre-filled and are discarded after use.
E-cigarettes are made up of metal coils and other metallic components that are in constant contact with e-liquid solution, which contains nicotine salt, flavorings, and organic acids. When nicotine salts are introduced into the e-liquid, and it is heated, it causes metal to dissolve. So when a smoker takes a puff, they’re inhaling aerosolized toxic metals as well as nicotine.
“We’ve known for a long time that when you heat a coil [in an e-cigarette] and it goes through the heat cycle, it will leach metals over time,” says Brett Poulin, PhD, assistant professor in the UC Davis Department of Environmental Toxicology and senior author of the study. “People have documented that in a lot of different electronic cigarettes. But the unique part of this study is that we found elements in what we call the ‘virgin e-liquid,’ meaning that the device has never been used.”
This design is known as a “closed system,” so you’re not changing out the coil, which Poulin says was a common feature of the previous-generation devices, and may help explain why the newer disposable e-cigarettes are more harmful. “And so when you have a closed system, you essentially just end up accumulating a lot of those metals over time, and you end up with higher concentrations in the aerosol that people breathe,” he tells Rolling Stone.
Additionally, the researchers found that disposable e-cigarettes contained antimony — a toxic metalloid — which wasn’t previously seen in older generations of e-cigarettes. “We identified [antimony] at high concentrations in the unused e-liquids of these devices,” says Mark Salazar, a PhD candidate in Poulin’s lab. “And we found that as the devices are aged and they’re puffed more and more, you’re producing more and more toxic antimony over time.”
So why are components that leach toxic metals being used in disposable e-cigarettes? “We can only speculate,” Poulin says, “but because they’re not reused, disposable e-cigarettes are only designed to be used through their life cycle, which can be anywhere between between 500 to several thousand puffs. You end up with a lot of cheap components, like a lead-based alloy.” He says it’s unclear why manufacturers are using these lower-quality parts, but says “it could be that there’s incentive to make cheaper products, and so they’re using materials that are cheaper in them, instead of something like stainless steel or a higher-quality metallic component.”
The researchers tested flavored and “clear” versions of three of the most popular products — Esco Bar, Flum Pebble, and ELF Bar — and found “excessive emissions of toxic metallic elements” in the aerosols from each of them. Currently, there are nearly 100 disposable e-cigarette brands on the market, but the Food and Drug Administration (FDA) has only authorized four products: NJOY DAILY Rich Tobacco (4.5 percent and 6 percent) and NJOY DAILY EXTRA Menthol (4.5 percent and 6 percent).
The manufacturers of Flum Pebble and Elf Bar did not immediately respond to our request for comment. A spokesperson for Eco Bar sent Rolling Stone the following statement: “The test that was conducted was not on an original EscoBar vape. It’s important for the researcher to understand that the market is flooded with counterfeit products from China. These fake vapes are typically untested and uncertified, and they are the ones that often show such irregularities. All of our vapes are lab-tested and fully approved.”
To assess whether the concentrations of toxic metals in these three disposable e-cigarettes would be of concern for human health, Salazar did a risk assessment based on an estimate of how much people typically use these devices, using 100 puffs per day as a benchmark — which Poulin says is “actually pretty conservative based on known use patterns.” From there, you can figure out how much toxic metal a smoker was exposed to. Lead, nickel, and antimony were all above the threshold of being safe.
To help put things in perspective, the researchers compared the health risks of disposable e-cigarettes to other types of smoking, and found that Esco Bar devices released more lead during a day’s use than 19 packs of traditional cigarettes.
What does this mean for disposable e-cigarette smokers’ health? “Nickel and antimony are respiratory carcinogens, so they can be essentially driving not just inflammation of the lungs, but also cancer,” Poulin says. “Lead is a potent neurotoxin, and our concern is that [disposable e-cigarettes] are often flavored devices, and they’re marketed towards youth. The concern is that adolescents and teens could be exposed to high levels of lead at a time when their neurological systems are developing.”
Smoking disposable e-cigarettes may also cause lung fibrosis, Salazar says, but that would likely happen further down the line. “These disposables have only been on the market for maybe about five, six years, and a lot of these diseases take years — maybe decades — to manifest,” he explains. “So we’re not entirely sure what the long-term effects are going to be, but from the data that we have presented, we see that there is potential for concern here.”
June 27, 8:10 p.m.: This article has been updated to include comment from Eco Bar .
