When used often, UV lamps used to dry gel nail polish can damage DNA and may increase the risk for skin cancer, according to a new study.

The dryers emit ultraviolet A light, which is linked to increased skin cancer risk. But do the dryers emit enough to warrant concern? To find out, researchers from the University of California, San Diego and the University of Pittsburgh tested the UV devices using cells from humans and mice. The results, published in Nature Communications, suggest practicing caution if you’re regularly exposed to UV-emitting devices.

Maria Zhivagui, a postdoctoral researcher at UC San Diego and the study’s first author, told NPR that she was alarmed by the results, particularly because she gets gel manicures every two to three weeks and even has a UV dryer at home. Such dryers are marketed as safe, and the Food and Drug Administration (FDA) considers them to be low risk.

Some cases of rare cancers on the nails and fingers have been seen among chronic gel polish users—such as pageant contestants—some of which have been linked to UV exposure. “We wanted to devise this study and design it in order to…address questions about the potential harms of these artificial UV lamps,” Zhivagui told NPR.

The study found that exposing cells to a UV lamp for 20 minutes, then removing them for one hour and exposing them again for 20 more minutes resulted in 20% to 30% cell death, while placing cells placed under a lamp for 20 minutes per day for three days resulted in 65% to 70% cell death. What’s more, damage was caused to mitochondria and DNA in the remaining cells.

In the study, the researchers summarize their findings:

“While this report demonstrates that radiation from UV-nail polish dryers is cytotoxic, genotoxic, and mutagenic, it does not provide direct evidence for an increased cancer risk in human beings. Prior studies have shown that an increase in mutagenesis will likely lead to an increase in cancer risk. Further, several anecdotal cases have demonstrated that cancers of the hand are likely due to radiation from UV-nail polish dryers in young females. Taken together, our experimental results and the prior evidence strongly suggest that radiation emitted by UV-nail polish dryers may cause cancers of the hand and that UV-nail polish dryers, similar to tanning beds, may increase the risk of early-onset skin cancer. Nevertheless, future large-scale epidemiological studies are warranted to accurately quantify the risk for skin cancer of the hand in people regularly using UV-nail polish dryers. It is likely that such studies will take at least a decade to complete and to subsequently inform the general public.”

In speaking with NPR, Zhivagui added that on average, nail salons use UV dryers that are quicker and more powerful than those used in the study and therefore the energy of the exposure could be higher.

Shari Lipner, MD, PhD, a dermatologist and director of the Nail Division at Weill Cornell, Medicine told NPR that the results confirm concerns about UV dryers among dermatologists, some of whom urge gel users to use sunscreen and fingerless, UV-absorbing gloves when getting manicures.

“I think even before the study, that was the way to go,” Lipner said. “And in light of the study, I think it should convince people even more to use caution.”

The FDA suggests limiting dryer use to 10 minutes per hand and removing any skin care products in advance because they can sometimes increase sensitivity to UV rays.

While advising caution, the study also states: “Future large-scale epidemiological studies are warranted to accurately quantify the risk for skin cancer of the hand in people regularly using UV-nail polish dryers. It is likely that such studies will take at least a decade to complete and to subsequently inform the general public.”