Dec. 6, 2012 -- Widely used UV nail lamps are highly unlikely to cause skin cancer, even if used weekly for 250 years, a new study suggests.
The finding contradicts the feeling of many dermatologists that the devices are as harmful as tanning beds. That feeling is largely based on a 2009 report of skin cancer on the hands of two women with no other obvious skin-cancer risks.
But the new study actually measured radiation from typical nail lamps. The measurements then were used to calculate nail lamps' "carcinogenic effectiveness" by the same method used to establish the safety of medical devices.
"Nail lamps are safe for over 250 years of weekly manicures, and even then there would be a low risk of skin cancer," says study researcher Alina Markova, MD, of Massachusetts General Hospital. "Not 'no risk,' but 'low risk.'"
Emory University dermatologist Jamie MacKelfresh, MD, praises the Markova study for its scientific approach.
"This makes me rethink the issue of nail lamp safety," MacKelfresh says. "I'm not ready to say these devices are safe -- we dermatologists want people to avoid UV radiation as much as possible -- but this seems to be low risk, especially if used infrequently."
The study looked at three models of UV nail lamps similar to about 90% of the hundreds of such products available for salon and home use:
Device A, with four 9-watt UV fluorescent bulbs.
Device B, with one 9-watt UV fluorescent bulb.
Device C, with six 1-watt LED lights.
Markova and colleague Martin A. Weinstock, MD, professor of dermatology at Brown University, measured the radiation from a 10-minute session under the lamps, which is more than people typically get in a nail salon.
They compared the cancer-causing potential of each device to a course of treatment with the FDA-approved UV phototherapy devices commonly used by dermatologists. These treatments carry a low cancer risk.
"Over 13,000 Device A or B and more than 40,000 Device C sessions lasting for 10 minutes would be required to be received at the nail salon to equal the UV dose received during one [phototherapy] course," Markova and Weinstock calculate.
Gel nails, which usually must be set under a UV nail lamp, require three 3-minute exposures per salon visit. That's much longer than the typical time normal nail polish takes to dry under the lamps.
In the 2009 report linking two women's skin cancers to nail lamps, researchers calculated that nail lamps expose people to as much radiation as tanning beds. But Markova says that study used the wrong method to calculate actual radiation exposure from the lamps.
She also notes that a 2010 industry study defending nail lamps used "incorrect" methods.
MacKelfresh says she's "impressed by the science" behind the Markova study.
"This at least opens the door to talking about the level of risk these units give to a person," she says. "It seems to put some science behind the claim that the dose of UV radiation you are receiving is quite low. But I'd like to see more research down the line."
The Markova study appears in an advance online publication by the Journal of Investigative Dermatology.