But according to an analysis published Wednesday in the New England Journal of Medicine, the exposure to formaldehyde from e-cigarettes, based on similar chronic use as tobacco, could be five to 15 times higher than from smoking cigarettes.

“It’s way too early now from an epidemiological point of view to say how bad they are,” said co-author James F. Pankow, professor of chemistry and engineering at Portland State University in Oregon. “But the bottom line is, there are toxins and some are more than in regular cigarettes. And if you are vaping, you probably shouldn’t be using it at a high-voltage setting.”