The nail dryers emit primarily UVA light the same kind of ultraviolet light used in tanning beds and are used to dry nail polish or to harden a gel manicure. Gel manicures are popular because they create long-lasting, shiny nails through a chemical gel that is painted on the nail in layers and cured under UV light after every coating.
Case reports of two women who developed squamous cell skin cancers on their hands have suggested an association between cancer and the UV nail light devices, but most doctors agree the risk is low.
In the new study, researchers from Georgia Regents University in Augusta conducted a random sampling of 17 different UV nail lamps found in salons to determine how much ultraviolet radiation is being emitted when clients dry their nails under the lights.
The study, published as a research letter this week in the journal JAMA Dermatology, found wide variation in the dose of UVA light emitted during eight minutes of nail drying or hardening. The dose, measured in joules per centimetre squared, ranged from less than one to eight.
There is a vast range in the amount of light coming out of these devices, said Dr Lyndsay R Shipp, the studys lead author and a postgraduate resident at the universitys Medical College of Georgia. The amount of UV exposure ranged from barely to significant, she said.
DNA damage that can lead to skin cancer is known to occur around 60 joules per centimetre squared, and none of the nail lamps came close to that number. However, the researchers estimated that for most of the lamps tested, eight to 14 visits over 24 to 42 months would reach the threshold for DNA damage to the skin.
The study authors noted that the risk from multiple manicure visits remains untested, but the study suggested that even with numerous exposures, the risk for carcinogenesis remains small.
Dr Shipp said, There is a theoretical risk, but its very low.
Lamps with higher-wattage bulbs emitted the highest levels of UV radiation, but it would not be easy for a salon client to check the wattage before using a machine. Dr Shipp said she sometimes uses the nail lamps and will continue to do so.
I do use them every couple of months, she said, noting that you can get that amount of exposure when driving down the road in your car.
- TARA PARKER-POPE