Electronic cigarettes appear to be safer than ordinary cigarettes for one simple — and simply obvious — reason: people don’t light up and smoke them.

With the e-cigarettes, there is no burning tobacco to produce myriad new chemicals, including some 60 carcinogens.

But new research suggests that, even without a match, some popular e-cigarettes get so hot that they, too, can produce a handful of the carcinogens found in cigarettes and at similar levels.

A study to be published this month in the journal Nicotine and Tobacco Research found that the high-power e-cigarettes known as tank systems produce formaldehyde, a known carcinogen, along with the nicotine-laced vapor that their users inhale. The toxin is formed when liquid nicotine and other e-cigarette ingredients are subjected to high temperatures, according to the study. A second study that is being prepared for submission to the same journal points to similar findings.