Mark Salazar, left, and Brett Poulin are in the lab with disposable vape pods. Photo courtesy of Kat Kerlin, University of California, Davis

SACRAMENTO REGION, CA (MPG) - They might look like travel shampoo bottles and smell like bubblegum, but after a few hundred puffs, some disposable, electronic cigarettes and vape pods release higher amounts of toxic metals than older e-cigarettes and traditional cigarettes, according to a study from the University of California, Davis.

For example, one of the disposable e-cigarettes studied released more lead during a day's use than nearly 20 packs of traditional cigarettes.

The study, published on June 25 in the ACS Central Science journal noted that although most disposable e-cigarettes are illegal in the United States, they remain widely available.

Most consumers of disposable e-cigarettes are teens or young adults, who are also highly susceptible to lead exposure. Inhaling certain metals can increase a person's risk of cancer, respiratory disease and nerve damage.

"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," said senior author Brett Poulin, an assistant professor in the University of California, Davis Department of Environmental Toxicology. "These risks are not just worse than other e-cigarettes but worse in some cases than traditional cigarettes."

First author Mark Salazar, a Ph.D. candidate in Poulin's lab, first saw a disposable vape pod when he was visiting a friend. The pods are self-contained cartridges that hold a battery, e-liquid and heating coil. Salazar was curious: what exactly was his friend smoking? Salazar brought the pod back to the lab at University of California, Davis and tested its vapor for metal concentrations.

"When I first saw the lead concentrations, they were so high I thought our instrument was broken," Salazar said. "That sparked us into looking further into these disposables."

The scientists analyzed the metal and metalloids inside seven types of disposable devices from three of the most popular brands. Using an instrument to activate disposable e-cigarettes and heat the internal liquid, they created between 500 and 1,500 puffs for each device.

They said that some devices emitted surprisingly high concentrations of elements in the vapor, including antimony and lead. Levels of chromium, nickel and antimony increased as the number of puffs increased. Most of the disposable e-cigarettes tested released markedly higher amounts of metals and metalloids into vapors than earlier, refillable vapes.

The scientists then took apart the devices to trace the metals’ sources.

"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," Salazar said. 

Shown is the inside of a vape pod, a type of e-cigarette, at University of California, Davis. Photo courtesy of Kat Kerlin, University of California, Davis

Leaded bronze alloy components in some devices leached nickel and lead to the e-liquid. Nickel was also released from heating coils and antimony was present in unused e-liquids at high levels, both of which increase the risk of cancer.

The researchers also assessed the health risk for daily users. Vapors from three of the devices had nickel levels and two devices had antimony levels that exceeded cancer risk limits. Vapors from four of the devices had nickel and lead emissions that surpassed health-risk thresholds for illnesses besides cancer, such as neurological damage and respiratory diseases.

While the researchers tested only three of the nearly 100 disposable e-cigarette brands on the market, they say that this initial work prompts concern, given the popularity of disposable e-cigarettes, especially among adolescents.

The market is also outpacing science. Few studies of the relatively new devices are available, leaving consumers and regulators largely uninformed. The work underscores the need to enforce regulations around illegal e-cigarettes while continuing research to reveal the extent of the problem and its public health implications.

The study's co-authors include Lalima Saini, Tran Nguyen, Kent Pinkerton, Amy Madi and Austin Cole from the University of California, Davis.

The research was supported with funding from the University of California Tobacco-Related Disease Research Program, the National Institute of Environmental Health Sciences T32 training program, and the University of California Agricultural Experiment Station.