The devices are a common fixture in nail salons, and generally use a particular spectrum of UV light (340-395nm) to cure the chemicals used in gel manicures. While tanning beds use a different spectrum of UV light (280-400nm) that studies have conclusively proven to be carcinogenic, the spectrum used in the nail dryers has not been well studied.

"If you look at the way these devices are presented, they are marketed as safe, with nothing to be concerned about," said Ludmil Alexandrov, a professor of bioengineering as well as cellular and molecular medicine at UC San Diego, and corresponding author of the study published in Nature Communications. "But to the best of our knowledge, no one has actually studied these devices and how they affect human cells at the molecular and cellular levels until now."

Using three different cell lines—adult human skin keratinocytes, human foreskin fibroblasts, and mouse embryonic fibroblasts—the researchers found that the use of these UV emitting devices for just one 20-minute session led to between 20 and 30 percent cell death, while three consecutive 20-minute exposures caused between 65 and 70 percent of the exposed cells to die.

Exposure to the UV light also caused mitochondrial and DNA damage in the remaining cells and resulted in mutations with patterns that can be observed in skin cancer in humans.