A new study led by Northwestern Medicine and the University of California, San Francisco offers compelling evidence that tanning beds mutate skin cells far beyond the effects of ordinary sunlight — reinforcing long-standing concerns about the safety of these devices.
Indoor tanning has previously been linked to a nearly threefold increase in melanoma risk. This study provides new insight into how tanning beds contribute to melanoma by inducing DNA damage across almost the entire skin surface.
Who’s Tanning, and Why?
The use of artificial light for therapeutic purposes dates back to the late 19th century when Danish physician Niels Ryberg Finsen pioneered ultraviolet (UV) light treatments for skin disease. The first modern tanning bed was introduced in 1978 by German scientist Friedrich Wolff. While the popularity of tanning beds waned as links to skin cancer became clearer — prompting the World Health Organization to classify UV radiation from tanning devices as a Group 1 carcinogen — its popularity has resurged in the 21st century, particularly among younger individuals and social media influencers.
New Evidence
Melanoma is the deadliest form of skin cancer, responsible for approximately 11,000 deaths annually in the United States. Although the epidemiologic link between tanning beds and melanoma has been well established, the biological mechanisms have been less clear. This study helps fill that gap.
Key findings include:
- Thousands of medical records were analyzed to compare melanoma rates in tanning bed users vs. non-users
- Researchers sequenced 182 skin biopsies from tanning bed users and matched controls
- Tanning bed users carried double the mutation burden of controls
- DNA mutations were detected even in body areas with minimal sun exposure
Investigators used new genomic technologies to perform single-cell DNA sequencing on melanocytes across three donor groups to test whether tanning beds cause more extensive DNA injury than sun exposure. The results showed widespread, melanoma-associated mutations in skin cells from indoor tanning users.
“Even in normal skin from indoor tanning patients, areas where there are no moles, we found DNA changes that are precursor mutations that predispose to melanoma,” said study first author Pedram Gerami, MD, professor of skin cancer research at Northwestern University Feinberg School of Medicine. “That has never been shown before.”
Dr. Gerami, who also directs the melanoma program in dermatology at Feinberg, has been treating melanoma patients for 20 years. He and his colleagues found that melanoma was diagnosed in 5.1% of tanning bed users compared with 2.1% of non-users. Tanning bed users were also more likely to develop melanoma on body sites that are typically shielded from the sun, such as the lower back and buttocks.
Understanding the Study
The first group included 11 of Gerami’s patients, all of whom had a long history of indoor tanning. The second group consisted of nine patients who had never used tanning beds but were otherwise matched for age, sex, and cancer risk profiles. The third group comprised six cadaver donors to complete the control group.
The scientists sequenced 182 individual melanocytes and found skin cells from tanning bed users carried nearly twice as many mutations as those from the control group and were more likely to contain melanoma-linked mutations.
“In outdoor sun exposure, maybe 20% of your skin gets the most damage,” Dr. Gerami explained. “In tanning bed users, we saw those same dangerous mutations across almost the entire skin surface.”
Looking Ahead
For Dr. Gerami, the findings reinforce both clinical experience and the need for stronger public health protections.
“Most of my patients started tanning when they were young, vulnerable and didn’t have the same level of knowledge and education they have as adults,” he noted. “They feel wronged by the industry and regret the mistakes of their youth.”
He recommends that anyone who has a history of indoor tanning undergo a full-body skin exam by a dermatologist. He also suggested that tanning beds carry warning labels similar to those used for cigarettes to better communicate long-term risks.
