Vaping, long touted as ‘healthier’ alternatives to smoking, may actually be more toxic than traditional cigarettes. 

Scientists from the University of California, Davis, conducted tests on seven flavored e-cigarettes sourced from three leading brands, discovering that these disposable vapes emit more cancer-causing toxic metals than traditional cigarettes.

One of the disposable e-cigarettes studied released more lead during a day’s use than nearly 20 packs of traditional cigarettes. 

The study’s main author, Mark Salazar, a PhD candidate, said the levels were so high he ‘thought our instrument was broken.’ 

The scientists analyzed the metals inside seven types of disposable devices from ELF Bar, Flum Pebble and Esco.

Using an instrument to activate the disposable e-cigarettes and heat the internal liquid, they created between 500 and 1,500 puffs for each device.

After using a device to simulate the equivalent of up to a week’s use, the team found they contained the heavy metals nickel, lead and antimony.

The heating coils, made from these metals, are responsible for transforming the e-cigarette liquid into an inhalable vapor, but the metals seep into the liquid during this process.

A new study from the University of California – Davis found vaping may release more cancer-causing chemicals than 20 cigarettes (stock image)

The graph above illustrates the levels of nickel, antimony, and lead found in the examined vapes. It compares these levels to the cancer risk thresholds: a green dotted line indicating this for lead, a purple one for antimony, and a red line showing the level associated with risks of non-cancer illnesses.

Vapor from three of the tested devices contained levels of lead and nickel above cancer safety limits, and two had elevated levels of antimony – an element used in batteries and as a flame retardant.

Esco Bars in particular were found to release four to 13 times more lead in their first 200 puffs than a pack of 20 cigarettes. This is the same amount of lead exposure as smoking 19 cigarettes in a single day. 

And four devices sold by Esco had levels of lead and nickel linked to respiratory and lung diseases like asthma and lung scarring.   

The researchers said while they only tested three out of 100 popular vape brands, the findings show concerning health risks for teens and young adults, who are most likely to use them.  

All three heavy metals tested are considered potential carcinogens, meaning they could cause cancer. And all have been associated with lung cancer, while lead has been shown to increase the risk of lung, kidney and brain cancers. 

Nickel has also been associated with nasal and sinus cancers. 

Though vapes are higher in these heavy metals than cigarettes, decades of research suggests cigarettes are still more dangerous because they contain about 7,000 carcinogens compared to 2,000 in vapes. 

Cigarettes have also long been proven to cause lung cancer, while research has not yet proven direct causation between vaping and the disease.  

Brett Poulin, senior study author and assistant professor in the UC Davis Department of Environmental Toxicology, said: ‘Our study highlights the hidden risk of these new and popular disposable electronic cigarettes – with hazardous levels of neurotoxic lead and carcinogenic nickel and antimony – which stresses the need for urgency in enforcement.

‘These risks are not just worse than other e-cigarettes but worse in some cases than traditional cigarettes.’

The study, published Wednesday in ACS Central Science, analyzed metal and metalloids – elements that have properties intermediate between metals and non-metals.

Using a device to heat and activate the e-cigarettes, they made each one generate between 500 and 1,500 puffs. 

The average vape user does about 100 to 200 puffs in a day. 

ELF Bar, which is also sold as EB Design (pictured here), was the most popular disposable vape of 2023 and 2024

The team found vapors from three of the devices – ELF Bar Flavored, ELF Bar Clear and Esco Bar Flavored – exceeded cancer risk limits for nickel. 

Meanwhile, Flum Pebble Flavored and Esco Bar Flavored exceeded these levels for antimony. 

And Esco Bar Flavored and Esco Bar Clear had lead emissions that surpassed health-risk thresholds for ‘non-cancer disorders.’ 

These include asthma and lung scarring fibrosis. 

Mark Salazar, first study author and PhD candidate in Poulin’s lab, said: ‘We found that these disposable devices have toxins already present in the e-liquid, or they’re leaching quite extensively from their components into e-liquids and ultimately transferred to the smoke.’

The above graphic shows the heavy metals in different parts of the tested disposable vapes

The CDC identified ELF as the most popular vape brand among teens and young adults in 2023 and 2024. And Esco Bars sold about $82million worth of products in the US in 2022, the latest data available. 

No flavored e-cigarettes are legal for sale in the US, though the FDA has authorized a limited number of unflavored ones.

However, both varieties remain pervasive at convenience stores and through online retailers. 

Sales data reported by Reuters estimated $2.4billion worth of illegal vapes were sold in the US last year, which experts say is particularly concerning because they are not regulated or tested by any oversight agency so it’s unclear what’s in them. 

About six percent of US adults – about 17million – vape, according to the latest CDC data. 

And roughly six percent of middle school students and eight percent of high school students report vaping at least once in the last 30 days. 

While they have generally been considered a safer alternative to smoking tobacco and promoted as a smoking cessation aid, recent research suggests e-cigarettes may increase the risk of heart and lung damage.

In a case study published this month, a New Jersey man died of what’s thought to be the first documented case of lung cancer caused by e-cigarettes.