Are UV nail lamps dangerous?

Due to some recent publications like the article “Are Gel Manicures Dangerous?” in The New York Times, or “UV dryers for gel nails can harm DNA, study says. Should I use them?” in Washington Post, a new wave of anxiety has been raised among gel manicure lovers. By the way, the previous wave was exactly the same and happened more than 10 years ago.

Despite the loud headlines, the authors of all these articles always make caveats like: “We can’t quantify the risk” or “However, the effect of radiation emitted by UV-nail polish dryers on the physiology and mutagenesis of mammalian cells remains unclear”, or “researchers cannot conclude, based on the study, that these dryers increase cancer risks.”.

Of course, some of my clients immediately started asking my opinion about this possible “new danger”. This article is my response.

First, a small disclaimer: I’m just a nail artist and not a scientist! But, because I care about the health of clients and strive to provide them with the safest service possible, I decided to delve deeper into this issue.

If you don’t like long reads and are just looking for a simple answer dangerous or not – the answer is extremely likely NOT. There is ZERO proven evidence that UV nail lamps can cause cancer or any other skin disease if used as intended.

Please notice, that some diseases, certain medications or supplements can make you more sensitive to UV rays.

The U.S. Food & Drug Administration

FDA in the article “How to Safely Use Nail Care Products” published in June 2017,  views nail curing lamps as:

“low risk when used as directed by the label. For example, a 2013 published study indicated that—even for the worst case lamp that was evaluated — 30 minutes of daily exposure to this lamp was below the occupational exposure limits for UV radiation. (Note that these limits only apply to normal, healthy people and not to people who may have a condition that makes them extra sensitive to UV radiation.)”

What you should really be worried about

Some clients, fearing the ultraviolet radiation, try to shorten the exposure time and take their hand out of the lamp before the timer runs out.

Honestly, this is a very bad idea because the risks of UV exposure in the lamp, even if they are there, are minuscule compared to the risk of getting chemical burns to the nail plate, and even the nail bed from undercured gel. This might happen because the still active chemical components of the uncured gel will interact with your nail for the next three or four weeks, and this unwanted interaction can eventually cause a chemical burn.

It’s also not the best idea to try to “cure” the gel better by keeping your hand in the lamp longer than the time the nail technician has set on the timer. This will not make your nails any stronger or better and will only cause additional unnecessary exposure to UV light.

If you are still worried

about possible UV exposure – wear UV-absorbing gloves that expose only your nails. Your nail bed is already well protected by the nail plate (read below). In the absence of gloves, you can apply a broad-spectrum sunscreen with an SPF of 15 or higher but, do it at least one hour before the procedure. If you apply sunscreen right before the manicure it can cause a service breakdown.

One of the studies on which the FDA based its conclusions about the safety of manicure lamps (including modern LED lamps) – “Photobiological Safety Evaluation of UV Nail Lamps” published in July 2013. The full text of the research is very technical and what is even more unpleasant – is hidden behind the paywall, but there is a free article with just compressed conclusions from this study made by Dr. John Dowdy and Dr. Robert Sayre. You can find it here “UV Nail Lamps Tested and Found Safe by Two Leading UV Experts”.

I will provide some citations from this work:

 – Because the measured UV exposure was so low, a person could go to their workplace and once every day put their hand under a UV nail lamp for 25 minutes and this would STILL be within the “permissible daily occupational exposure limits” for workers, according to the applicable international standard (ANSI RP-27). Obviously, salon client exposure is much, much lower, and just a tiny fraction in comparison and it must be considered also that client exposure is only twice per month. This scientific paper provides powerful evidence to further support the safety of UV nail lamps; either traditional tube or LED-style.

– This study also demonstrates that risks for the development of non-melanoma skin cancer (NMSC) are very low when compared to normal noon sunlight. Of the types of UV that can cause NMSC, this study found that UV nail lamps expose skin to somewhere between 11-46 times less NMSC-related exposure expected from spending equal time in natural noon sunlight, “…the UV nail lamps had 11-46 times less NMSC effective irradiance than an overhead 1-atmosphere solar spectrum [normal noon sunlight].”

– When sharing his opinions based on this nail lamps testing Dr. Sayre has said that some, “Physicians are grossly exaggerating exposures.” And of UV nail lamps he says, “…this UV source probably belongs in the least risky of all categories.” And, “UV nail lamps are safer than natural sunlight or sunlamps.”

– “… the UV exposure risks to the nail bed is comparable to that of skin protected by high SPF topical sunscreen.” Research studies indicate the nail plate’s natural UV resistance is comparable to the UV resistance provided by an SPF 40 sunscreen

– Also cited was additional research to demonstrate that the backside of the hand is 4 times more resistant to UV than the forehead or cheek. It is 3.5 times more resistant than the person’s back, making the backside of the hand THE most UV-resistant part of the body, “The dorsum [backside] of the hand is the most UV acclimatized, photo adapted, and UV-resistant body site.”

If you don’t trust the FDA and scientists (whom to trust then?) or just want to know more, let’s go deeper into it.

Let’s start with UV light or Ultraviolet – it is a form of electromagnetic radiation with wavelengths shorter than that of visible light. UV radiation is present in sunlight and constitutes about 10% of the total output of the Sun.

UV radiation from the Sun is divided into three main bands: UVA, UVB, and UVC.

– UVA (315-400 nm) radiation has the longest wavelength and lowest energy of the three bands. It is the most abundant form of UV radiation reaching the Earth’s surface. UVA radiation can cause premature skin aging, wrinkles, and age spots. It can penetrate into the deeper layers of the skin and is responsible for the immediate tanning effect. It can also contribute to the development of skin cancer. This type of radiation is the most important for our topic. Why so, you will understand further.

– UVB (280-315 nm) radiation has a shorter wavelength and higher energy than UVA radiation. This radiation is mostly absorbed by the ozone layer, but some of it reaches the Earth’s surface. It is responsible for sunburns and premature skin aging. UVB radiation is also the main cause of skin cancer, including melanoma, the deadliest form of skin cancer. Ironically, UVB wavelengths happen to be the specific wavelengths that trigger vitamin D production in our skin. Vitamin D is essential for strong bones and teeth. Vitamin D also plays a role in the immune system, muscle function, and cell growth.

– UVC (100-280 nm) radiation has the shortest wavelength and highest energy of the three bands. It is the most harmful form of UV radiation, but it is mostly absorbed by the ozone layer and does not reach the Earth’s surface.

Now let’s take a closer look at UV lamps used in the modern nail industry

The most popular UV lamps on the market in 2023 – are LED UV lamps. These lamps use Light-emitting diodes (LEDs) that are manufactured to emit radiation in the ultraviolet range.

Currently, the most common types of UV LEDs are in 395 nm and 365 nm wavelengths, both of which are in the UV‑A spectrum. In all modern UV nail lamps are used 395 nm UV LEDs, they are cheaper in production and more suitable. They emit radiation in the visible spectrum (which is 380 – 700 nm) and give off a purple color.

UVA rays are present in sunlight all year round, regardless of the time of day or the season. This means that we are all exposed to a high level of UVA rays throughout our lives.

Thus, almost all modern UV LED lamps for manicures emit the most common and familiar to our skin visible ultraviolet spectrum (type UVA) in a very narrow range of wavelengths to react and activate the photo-initiators in a gel (tiny molecules called oligomers) – that “cure” when exposed to UV light.

The narrow range is very important because old UV nail lamps equipped with mercury arc bulbs or microwave bulbs were emitting UV radiation in a broader spectrum, and could include more harmful for us UV-B radiation. And even these older UV nail lamps equipped with bulbs (not LEDs) were found safe.

How it began

The story about the danger of UV nail lamps started with the report «Occurrence of nonmelanoma skin cancers on the hands after UV nail light exposure» published by Deborah F MacFarlane and Carol A Alonso in April 2009. The report suggests that two women developed skin cancer due to exposure to UV nail lamps.

After publishing, their conclusions were heavily criticized. For example, in the article “Do UV Nail Lamps Emit Unsafe Levels of Ultraviolet Light?” published in 2009, or “FDA Weighs In on UV Curing Nail Lamps” published in 2017.

In the first one, three leading scientists in the professional nail industry expressed their surprise at claims of the cancerogenic danger of UV nail lamps. “To verify the facts, using an independent laboratory we tested the leading UV nail lamps to determine how much UV-A and UV-B they emit and then compared that to natural sunlight”.

It is worth mentioning that they tested the old UV nail lamps with bulbs inside, not modern UV LED lamps.

“Test results show that UV-A exposure for client skin is equivalent to spending an extra 1.5 to 2.7 minutes in sunlight each day between salon visits, depending on the type of UV nail lamp used. A nail lamp with two UV bulbs corresponds to 1.5 minutes and a nail lamp with four UV bulbs corresponds to about 2.7 minutes each day between salon visits.”

MacFarlane and Alonso claimed to find two cases of skin cancer that they suggest were caused by UV nail lamps. Both of their patients live in Texas, a climate where significant incidental UV exposure from sunlight is inevitable even in the absence of deliberate recreational exposure. One patient had been exposed to a UV nail lamp only eight times during the same year (we assume every two weeks for 4 months). During this same period, the patient would have been exposed to more UV-A and UV-B simply by spending 10 to 20 minutes eating her lunch outdoors in natural sunlight once per week.

Oddly, the authors described this patient as a 48-year-old white woman who claimed to have “moderate recreational UV exposure”. We fail to understand how, under the circumstances, it could be concluded that this case of nonmelanoma skin cancer is caused by these eight exposures to a UV nail lamp, especially in light of the low levels of UV exposure expected during these few visits to a salon. We respectfully disagree and believe the results of Light Science’s independent testing are in agreement with our own laboratory findings supporting the safety of UV nail lamps.

In the research on which the aforementioned New York Times and Washington Post articles were based – “DNA damage and somatic mutations in mammalian cells after irradiation with a nail polish dryer” published in March and January 2023, the authors tried to “evaluate the DNA damage and mutagenic effects of ultraviolet radiation emitted by a nail polish UV-dryer”.

To estimate the damaging effect, they: “treated with ultraviolet light (UV) emitted from a UV-nail polish dryer for 20 min, twice a day within one single day, termed acute UV exposure. For chronic UV exposure, primary cells were exposed consecutively in three different days with each exposure lasting 20 min.” and “Primary HEKa cells were irradiated in 10-cm dishes using UV-nail polish dryer for 20 minutes for three consecutive days”

But again, the authors used an older A 54-W UV nail drying machine with 6 bulbs, which are exactly the same type of bulbs that are used in tanning beds. Why they hadn’t used any modern LED UV lamps for their study – remains unknown. Also, it is a question for me how continuous 20 minutes of exposure twice a day or three times in three days can mimic regular gel manicures in salon when single exposure usually doesn’t exceed 30-120 seconds and the intervals between salon visits are usually three to four weeks.

“Dermatologists who were not involved in the study told The Post it is important to note that the researchers examined human cells — not human beings, who have multiple layers of skin that provide additional protection against UV rays”

Or “If you sat every day with your hands under one of these machines, that’d be a problem,” said Melissa Piliang, a dermatologist at the Cleveland Clinic who has spoken about risks associated with UV lamps.”

Anyway, their conclusion: “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…”

The only problem with their conclusion, that is  – sunlight is not less cytotoxic, genotoxic, and mutagenic...

Experiment on the windowsill

To estimate the amount of ultraviolet light in the direct afternoon sunlight, I decided to conduct my own experiment right on my windowsill. It is simple, of course – not scientifically accurate, but it is quite illustrative. To do this, I applied different gel products to a clear plastic plate in the amount that I would apply to the nail plate of my client. Results I put into this table.

My results show that the intensity of ultraviolet radiation in direct sunlight probably is not very different from the intensity of radiation in the LED UV nail lamp. The longer time required for gel curing in sunlight can be explained by the fact that the sun emits ultraviolet light in a broad spectrum, while the lamp, in a much narrower spectrum, for which gels are adjusted, also on the windowsill, plate with gels is irradiated by the sun only from one direction, while in the lamp, light is emitted by tens of light emitting diodes and distributed evenly in all directions, which accelerates gel curing.