A new study suggests that E-cigarette vapor can contain cancer-causing formaldehyde at levels up to 15 times higher than regular cigarettes.
Researchers from Portland State University found that E-cigs operated at high voltages produce vapor with large amounts of formaldehyde.
They say this poses a risk to users who increase the voltage on their E-cig to increase the delivery of vaporized nicotine.
A Bay Area expert says he's concerned about what people inhale in the vapor but the study needs more context.
"There may be more formaldehyde bound to other compounds when you crank up the voltage, but formaldehyde is not the only carcinogen in tobacco smoke," expert John Balmes said.
The study is published in the New England Journal of Medicine.