E-cigarettes (a.k.a. vaporizers or vapes) aren't necessarily a safe substitute for the real thing. Smoking tobacco-free e-cigarettes still damages the users' DNA, increases the rate of genetic mutations, and raises the risk of cancer, according to a new study published in Proceedings of the National Academy of Sciences and spotted by Technology Networks.

E-cigarettes are often touted as a healthier way for nicotine addicts to get their fix because vaporizers don't contain tobacco. Smokers inhale water vapor from liquefied nicotine, which doesn't contain the same kinds of cancer-causing chemicals as tobacco-based cigarettes. But the current study findings call that assumption into question.

Researchers from New York University School of Medicine exposed the mice to smoke for three months, and then examined their DNA. They found adducts, a form of DNA damage in which a piece of the genetic material bonds to a chemical. This alters the DNA structure and can increase the risk of mutation. DNA can repair itself, but, the researchers observed, the repair protein levels had also dropped.

To see if e-cigarette smoke would affect humans similarly, they also exposed lung, heart, and bladder cells to nicotine and nitrosamine, a carcinogenic chemical compound formed by the human body when it processes nicotine. Nitrosamines can cause tumors to form, and sub-chemicals can bind to and alter DNA.

These human cells showed the same type of DNA damage found in mice that had been exposed to e-cigarette smoke. The nicotine predisposed the cells to undergo two to four times more spontaneous mutations after additional exposure to environmental triggers, like UV rays.

"Based on these results, I cannot conclude that e-cig smoke is safer than tobacco smoke in terms of cancer susceptibility of smokers," study co-author Moon-shong Tang said, according to Technology Networks.

[h/t Technology Networks]