Indoor tanning accelerates genetic aging of skin: UCSF study

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Young adults who use tanning beds may be aging their skin cells at a molecular level much faster than their chronological age suggests, according to a new study from the University of California, San Francisco (UCSF) and Northwestern University. The research, published December 12 in Science Advances, reports that tanning bed users in their 30s and 40s harbour more mutations in their skin cells than nonusers who were in their 70s or 80s.

“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,” said Bishal Tandukar, PhD, in a press release. Dr. Tandukar is a postdoctoral scholar in dermatology at UCSF and the study’s co-first author. “In other words, the skin of tanning bed users appeared decades older at the genetic level.”

The findings add a critical molecular dimension to the long-established link between indoor tanning and skin cancer. DNA mutations associated with ultraviolet (UV) exposure—whether from sun or artificial sources—accumulate over time and are known precursors to malignancy. Skin cancers remain the most commonly diagnosed cancers in the United States, according to the American Cancer Society. While melanoma represents only about 1% of cases, it accounts for the majority of deaths, with approximately 11,000 Americans dying from melanoma each year.

In this study, researchers examined data from more than 32,000 dermatology patients, analyzing their tanning bed use, history of sunburn, and family history of melanoma. Tissue samples from 26 donors were sequenced at the single-cell level, revealing extensive mutational changes—particularly in areas such as the lower back, which typically receive little natural sun exposure but are directly exposed in tanning devices.

“The skin of tanning bed users was riddled with the seeds of cancer—cells with mutations known to lead to melanoma,” said senior author A. Hunter Shain, PhD, associate professor in UCSF’s Department of Dermatology. “We cannot reverse a mutation once it occurs, so it is essential to limit how many mutations accumulate in the first place. One of the simplest ways to do that is to avoid exposure to artificial UV radiation.”

Many provinces across Canada have banned the use of tanning equipment for people under the age of 18. However, despite mounting evidence, tanning beds remain legal and accessible in the United States, even as the World Health Organization classifies them as group 1 carcinogens—on par with tobacco and asbestos.

The research underscores the irreversible nature of UV-induced genetic damage and the need for preventive dermatology strategies, the researchers say.