“Disposable vapes may be more toxic than cigarettes, study finds,” says the San Francisco Chronicle. Fox News warns that vapes are “more carcinogenic”, and countless outlets echoed the same punch-line: newer single-use vapes are deadlier than combustible tobacco.
That framing is potent click-bait, but it’s only half the story.
What the UC Davis Team Did
UC Davis published the following study on June 25, 2025: Elevated Toxic Element Emissions from Popular Disposable E-Cigarettes: Sources, Life Cycle, and Health Risks
| Study detail | Why it matters |
|---|---|
| Devices | Seven disposables (Elf Bar BC5000, Esco Bar, Flum Pebble — two flavors each) bought mid-2023 |
| Age of stock | Two of the worst-performing Esco Bars were already out of production for > 2 years – effectively “vape antiques.” |
| Protocol | Baseline liquid -> 500 / 1000 / 1500 machine-generated puffs; metals in liquid & aerosol measured by ICP-MS. |
| Risk model | Concentrations were plugged into U.S. EPA lifetime-inhalation equations (assumes 20 m3 of air every day). A typical human vaper inhales 0.4 m3 of aerosol. |
What the Paper Shows Us
E-liquid inside of disposables are in constant contact with materials inside of the device. The researchers found elements leaching from various sources within the device, for example:
- Heating Coils: Chromium (CR), Nickel (Ni), Iron(Fe)
- Sheaths and Battery Connectors: Copper (Cu), Lead (Pb), Zinc (Zn)
- Wiring Solder: Tin (Sn), Copper (Cu)
Here’s how that translates to real issues.
- High levels of lead are possible. One Esco Bar liquid contained >=170 microgram/kilogram lead, traced to a bronze battery contact.
- Metals rise with use. Nickel, chromium and antimony increased as puff counts climbed, signaling coil degradation.
- Two real outliers caused the alarm. Only two of the seven devices exceeded both cancer and non-cancer thresholds. Five others fell within the Permissible Daily Exposure (PDE) limits used for inhaled medicines once you normalise to about 5 mL e-liquid per day – a point highlighted by independent tobacco-harm-reduction researcher Dr Konstantinos Farsalinos on X (see screenshot below).
- Poor design invites leaching. Disposables often keep liquid in constant contact with metal components – sometimes for months in hot shipping containers, which gives corrosion more time to work than in refillable tanks.
Where the Narrative Breaks Down
“Vape emits more lead than 20 packs of cigarettes.” – That finding came from one device; lead was already in the liquid before the first puff, suggesting a bad alloy rather than vaping per se.
“Disposables are more toxic than cigarettes.” – The study compared three heavy metals – but not tar, carbon-monoxide, PAHs, benzene, or the other 7,000 chemicals in smoke.
“All disposable vapes are dangerous.” – The sample size was seven units out of thousands on the market, and the two that caused alarm are no longer sold.
Cancer risk numbers – This was calculated as if a person vaped continuously 24 hours a day. Adjusting to realistic puff volumes drops risk by roughly an order of magnitude.
The Real-World Risk Picture
Leaching is plausible, especially for stock that sits in a warehouse for years. Lead, nickel, and antimony are cumulative toxins linked to cardiovascular disease, neuro-developmental harm, and certain cancers.
It’s important to understand that the level of exposure matters. In modern refillable devices with stainless-steel coils, independent surveys generally find metal intake below inhalation-medicine PDEs.
Waste caused by disposables also amplify the problem. Not only are there environmental and ethical concerns with mining lithium for batteries, but every tossed disposable adds a lithium battery, a circuit board, and (sometimes) leaded scrap to landfills. None of this happens with a 60 mL bottle of e-liquid and a reusable pod.
Practical Takeaways for Consumers & Regulators
- Don’t vape old disposables. If you can’t verify a manufacturing date, skip it. Aging + tropical shipping containers = higher leaching.
- Choose refillables. Replaceable-coil pod systems made by companies that publicly release materials data are a far safer bet than throw-aways of unknown origin.
- Batch-coded expiry labels & recall authority. Manufacturers need to be regulated. The vape industry isn’t independent anymore. It’s big-business. And big businesses will do whatever they can to cut costs. They need to be regulated.
- If it looks or tastes off, toss it. Cloudy liquid, metallic taste, or a device left roasting in a hot car is a red flag.
So, Is Vaping “Worse Than Cigarettes”?
Vaping? No.
Disposables? Maybe, but with caveats.
If your metric is lead per puff, a couple of outlier vapes beat cigarettes in the worst possible way. If your metric is overall mortality risk, they are still dramatically safer, because they produce no carbon monoxide, no tar, and far fewer carcinogens than smoldering tobacco.
What the UC Davis study really exposes isn’t that vaping is more deadly than smoking; it’s that the disposable segment is a regulatory Wild West where sloppy manufacturing can spike an otherwise lower-risk product.
As Dr. Farsalinos also states: “When a farmer sells rotten vegetables, the problem is not the vegetables in general. It is the farmer….”
Disposables as a whole aren’t a problem. It’s the manufacturer and/or the design of their product.
Final Word
The lesson isn’t to ditch vaping for cigarettes – it’s to be cautious of disposables and to understand the risks of using them, especially if they’re old, stored improperly, or made by untrustworthy companies.
There are lot of reasons disposables have taken over the market. They’re cheap, convenient, easy to use, and they have great flavor. But as we’ve seen from this study, they have drawbacks. While not as convenient, you could avoid those drawbacks by switching to refillable products.
Regulators are far behind when it comes to disposables, so unfortunately, consumers need to vet the products they use themselves. And that’s not easy when you don’t have scientific equipment to run your own tests.
Alex is a former smoker who successfully quit smoking after 14 years by switching to vaping. Now a pro-vaping advocate, Alex has become a seasoned expert with over a decade of experience in the vaping industry. Since starting his vaping journey in 2010, Alex has earned a reputation as a trusted reviewer, extensively testing all types of vape gear, including mech mods, sub-ohm tanks, RDAs, disposables, e-juices, boro devices, squonkers, dry herb vaporizers, and e-rigs. He’s also explored the craft of coil building and DIY e-juice.
Since 2015, Alex has published more than 800 in-depth articles on vaping, produced over 500 videos covering product reviews, industry news, and tips, contributed to several well-known vape publications, and hosted a popular vaping podcast featuring over 100 episodes and nearly 40 hours of content.