A new study finds that vaping may actually carry some of the same cancer risks as the cigarettes they’re supposed to be replacing.

Mouth swabs taken from smokers and vapers found similar changes to the DNA of cells inside their mouths, the same changes that could be a precursor to lung cancer.

Correspondent Vicki Barker says while researchers admit it does not necessarily mean the patients will get cancer, it shows that vaping is not as safe as some believe.

“This is the first study to investigate the impact of smoking and vaping on different kinds of cells — rather than just blood — and we’ve also strived to consider the longer-term health implications of using e-cigarettes,” said study author Chiara Herzog, a researcher at University College London’s EGA Institute for Women’s Health and Austria’s University of Innsbruck, in a statement.

“While the scientific consensus is that e-cigarettes are safer than smoking tobacco, we cannot assume they are completely safe to use, and it is important to explore their potential long-term risks and links to cancer,” Herzog said. “We hope this study may help form part of a wider discussion into e-cigarette usage — especially in people who have never previously smoked tobacco.”