Ever since nail polish addicts discovered the shiny, long-lasting allure of gel manicures, derms have thrown up a cautionary flag about the UV lamps used to cure the polish. Are salongoers subjecting themselves to cancerous rays in the name of beauty? Will one mani put you in serious health danger?

A few studies have attempted to answer these questions, and concluded that the risk of skin cancer associated with UV nail lamps is very low. But what these studies failed to consider is that each salon’s drying device may vary, and even more, each bulb in each drying device may vary. That leaves a lot of uncertainty.

To get a more complete view of the potential dangers, researchers at Georgia Regents University, Augusta, conducted a small study based on random UV light sampling of 17 different UV drying devices in 16 salons. They counted the number of bulbs in each lamp, recorded their wattage and measured the average amount of UVA radiation a person would be exposed to at five different positions (since not everyone holds her hands under the light the same way).

What they found was that the wattages and number of bulbs, and the strength of UV radiation varied widely. In fact, the lamp with the highest UVA output was more than 25 times stronger than the one at the bottom of the range.

“Individuals utilizing these lamps in salons have no way of knowing just how much UV exposure their skin is receiving upon each manicure,” says Chris Adigun, M.D., assistant professor of dermatology in the Ronald O. Perelman Department of Dermatology at NYU Langone Medical Center, who was not involved in the study. This lack of regulation among manufacturers could lead to varied malignancy risk from lamp to lamp and salon to salon.

The study results showed that lamps with higher wattages emitted higher levels of UVA radiation. The researchers went on to calculate how many gel manicures one would have to get at each salon to reach the radiation threshold shown to cause DNA damage. In every case, it would take multiple visits to hit dangerous levels of UVA radiation. But, again, the range was wide. At the salon with the lamps that produced the lowest irradiance, a woman would need to get 208 gel manicure to find herself in the danger zone, compared with just eight visits to the salon using the highest-radiation lamps. The authors write, “Although the in vivo risk from multiple manicure visits remains untested, our data suggest that, even with numerous exposures, the risk for carcinogenesis remains small.”

The bad news: It’s impossible for you to know your precise risk each time you settle into the salon chair, since devices vary so much. To minimize your exposure each time, Adigun recommends, as do the study researchers, to apply a broad-spectrum sunscreen to your hands before going under the lamps, or wear UVA protective gloves with the fingers clipped off to really limit the risk of both skin cancer and photoaging.

Realistically though, most people aren’t going to show up for their mani appointment with a tube of zinc oxide or sun-protective gloves stuffed into their purse. If you can’t live without your gels, you have to decide for yourself whether or not it’s worth the potential risk.