A common fixture in nail salons and home beauty supplies alike, UV nail dryers are like mini hand tanning beds.
These portable lamps emit beams of ultraviolet light to quickly dry nail polish formulations, known as shellacs, or gels, so they don’t smear on furniture.
But a new study warns that these devices are more of a public health concern than previously thought — and can cause cancer, much like sunbeds.
Researchers at the University of California San Diego found that its use leads to cell death and cancer-causing mutations in human cells.
UV lights, a common fixture in nail salons, use a specific spectrum of UV light to harden gel polish or shellac (gel polish mixed with regular polish). But researchers at the University of California, San Diego, say its health impact has been underestimated
Despite this, UV lamps tend to be sold without much regard for their potential health risks, according to the experts who published their study in Nature Communications.
“If you look at the way these devices are presented, they are marketed as safe, and you don’t have to worry,” said Ludmil Alexandrov, a professor of bioengineering and cellular and molecular medicine at UC San Diego.
“But as far as we know, no one has really studied these devices and how they affect human cells at the molecular and cellular levels yet.”
Professor Alexandrov and his colleagues note reports in medical journals of people who frequently undergo manicures, such as pageant contestants and estheticians, now suffering from rare cancers of their fingers.
“What we saw was that there was no molecular understanding of what these devices were doing to human cells,” he said.
Ultraviolet light, which has a shorter wavelength than visible light, is separated into three classifications by wavelength – UVA, UVB, and UVC.
Generally, UV lights contain lamps that emit wavelengths between 340 and 395 nanometers – so it’s in the UVA category.
UVA, the longer wavelength ultraviolet light, is already known to cause tanning and has been shown to contribute to skin cancer.
Tanning beds use fluorescent lamps that emit mostly UVA, with smaller doses of UVB, and have been conclusively shown to be carcinogenic, but the light from nail lamps has not been well studied, despite having a similar wavelength.
Shown here is the spectrum of visible and invisible light. The three types of UV rays are classified according to their wavelength
Tanning beds (pictured) use a different spectrum of UV light (280-400nm) that studies have conclusively shown to be carcinogenic, but the spectrum used in nail dryers has not been well studied
In their study, the researchers used two types of human cells — keratinocytes and fibroblasts — as well as cells extracted from mouse embryos.
In petri dishes, the three cell types were exposed to two different conditions—”acute exposure” and “chronic exposure”—under UV lamps.
For acute exposure, dishes containing one of the cell types were exposed for 20 minutes before being taken out for 1 hour to repair or return to original condition and then exposed again for 20 minutes.
Meanwhile, under chronic exposure, cells were placed under the machine for 20 minutes per day for three consecutive days.
The researchers found that a single 20-minute session resulted in 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 also damaged the mitochondria and DNA in the remaining cells and resulted in mutations in patterns that can be seen in melanomas in humans.
Overall, the results indicate that frequent or frequent use of these devices harms human cells, the team says.
Unprotected exposure to both UVA and UVB damages the DNA in skin cells, resulting in mutations that can lead to skin cancer.
The team admits that UVA rays can penetrate skin more deeply and are poorly absorbed by DNA, so they do little direct damage to DNA compared to UVB rays.
By contrast, UVB rays penetrate the outermost layer of the skin and “stimulate a large number of DNA lesions,” they say.
Currently, some sources on the Internet state that UV lamps are safe.
According to the Food and Drug Administration, UV lights pose low health risks “when used as directed on the label.”
Staining shows DNA damage of mouse (MEF) and human (HFF and HEKa) cells under acute and chronic exposure conditions, compared to control cells that did not receive UV lamp treatment.
Meanwhile, a 2014 study in JAMA Dermatology found that the level of UV exposure associated with bi-weekly manicures isn’t high enough to significantly increase skin cancer risk.
Experts at Harvard University suggest that wearing sunscreen or wearing a pair of fingerless gloves during a manicure can give cuticles extra protection.
Interestingly, other consumer products use UV light in the same range, including the tool used to treat dental fillings and some hair removal treatments.
But researchers at the University of California, San Diego say that UV lights are used more regularly, which makes them a bigger concern.
However, a long-term epidemiological study is needed to show that the use of UV lamps for nails results in an increased risk of skin cancer.
“These studies will likely take at least a decade to complete and inform the general public later.”
