Researchers found that e-cigarettes operated at high voltages produce vapor with large amounts of formaldehyde-containing chemical compounds.
This could pose a risk to users who increase the voltage on their e-cigarette to increase the delivery of vaporized nicotine, said study co-author James Pankow, a professor of chemistry and civil and environmental engineering at Portland State University in Oregon.
"We've found there is a hidden form of formaldehyde in e-cigarette vapor that has not typically been measured. It's a chemical that contains formaldehyde in it, and that formaldehyde can be released after inhalation," Pankow said. "People shouldn't assume these e-cigarettes are completely safe."
The findings appear in a letter published Jan. 22 in the New England Journal of Medicine.
Health experts have long known that formaldehyde and other toxic chemicals are present in cigarette smoke. Initially, e-cigarettes were hoped to be without such dangers because they lack fire to cause combustion and release toxic chemicals, a Portland State news release said.