A new study from UCSF and Northwestern finds that indoor tanning leaves young adults’ skin genetically older than that of many seniors, packed with DNA changes that can lead to melanoma. The work adds fresh urgency to warnings about tanning beds and artificial UV light.
Indoor tanning may give the appearance of a quick glow, but beneath the surface it is rapidly aging skin at the genetic level and loading it with cancer-linked damage, according to a new study from the University of California San Francisco and Northwestern University.
Researchers report that young adults who use tanning beds carry more DNA mutations in their skin cells than people in their 70s and 80s who do not use tanning beds. Those mutations are the kind that can set the stage for melanoma and other skin cancers.
The study, published Dec. 12 in the journal Science Advances, is the first to show that indoor tanning in youth is tied to such an extreme buildup of genetic damage.
The team was struck by how much more damaged the skin of indoor tanners looked when they examined it at the molecular level.
“We found that tanning bed users in their 30s and 40s had even more mutations than people in the general population who were in their 70s and 80s,” co-first author Bishal Tandukar, a postdoctoral scholar in dermatology at UCSF, said in a news release “In other words, the skin of tanning bed users appeared decades older at the genetic level.”
Skin cancer is the most common cancer in the United States, according to the American Cancer Society. Melanoma, the deadliest form, makes up only a small fraction of skin cancer cases but causes most skin cancer deaths. About 11,000 Americans die from melanoma each year, largely due to exposure to ultraviolet (UV) radiation.
UV radiation is present in sunlight but is also produced by artificial sources such as tanning beds. As indoor tanning has become more popular, especially among young women who make up the bulk of tanning salon customers, melanoma rates have climbed in parallel.
Many countries have effectively banned tanning beds, and the World Health Organization classifies them as a group 1 carcinogen, the same category as tobacco smoke and asbestos. In the United States, however, tanning beds remain legal and widely used.
To better understand how indoor tanning affects skin at the DNA level, the researchers took a two-pronged approach.
First, they analyzed medical records from more than 32,000 dermatology patients. Those records included information about tanning bed use, history of sunburns and family history of melanoma. This large dataset helped the team connect patterns of UV exposure with skin cancer risk factors across a broad population.
Then, to zoom in on the cellular damage, they collected skin samples from 26 donors and sequenced 182 individual skin cells. By reading the DNA of these cells, the scientists could count how many mutations had accumulated and identify the types of mutations most closely linked to UV exposure and melanoma.
The results were stark. Young adults who used tanning beds had more mutations in their skin cells than people twice their age who did not use tanning beds. The effect was especially strong in the lower back, a body area that typically gets little natural sun but is heavily exposed in tanning beds. That pattern strongly points to artificial UV light as the culprit.
The team saw clear warning signs of future cancer in the samples from tanning bed users.
“The skin of tanning bed users was riddled with the seeds of cancer — cells with mutations known to lead to melanoma,” senior author A. Hunter Shain, an associate professor in the UCSF Department of Dermatology, said in the news release.
Those mutations are permanent changes to DNA. Once they occur, they cannot be erased. Over time, as more mutations build up, the odds increase that one cell will acquire just the right combination of changes to become cancerous.
Shain emphasized that this is why prevention is so important.
“We cannot reverse a mutation once it occurs, so it is essential to limit how many mutations accumulate in the first place,” he added. “One of the simplest ways to do that is to avoid exposure to artificial UV radiation.”
Public health experts have long warned that there is no such thing as a safe tan from UV light, whether from the sun or a tanning bed. This study adds powerful genetic evidence that indoor tanning in youth can make skin biologically older and more vulnerable to cancer decades before wrinkles or sun spots appear.
For students and young adults, the findings underscore that choices made now can shape health risks later in life. A few minutes in a tanning bed may seem harmless, but at the DNA level those sessions are adding up to years of extra wear and tear.
The researchers say their work supports stronger efforts to discourage indoor tanning, especially among young people, and to educate the public about the hidden genetic damage caused by artificial UV light. Future studies may explore whether certain individuals are even more vulnerable to this damage due to their genes or skin type, and how best to target prevention campaigns.
For now, the message is straightforward: protecting your skin from UV radiation, particularly from tanning beds, is one of the most effective ways to reduce the number of cancer-causing mutations your cells accumulate over a lifetime.