When Heidi Tarr was a teenager, she used a tanning bed several times a week with her friends because they all wanted to glow like a celebrity.

“It was just the thing to do — everyone wanted that nice, dark, tan skin,” the 49-year-old market researcher told AFP via video call from Chicago.

Then one day in her 30s, Tarr noticed a strange mole on her back.

It was a melanoma — the deadliest form of skin cancer. She was lucky to have caught it early on, but has needed over a dozen biopsies to remove more moles.

Now her 15-year-old daughter Olivia is seeing trending videos on TikTok of people showing off their tan lines — and is asking her mother how to get some.

So Tarr was inspired to get yet another skin sample removed, this time to be used in research published in the journal Science Advances on Friday.

The study found that people who use tanning beds are nearly three times more at risk of getting skin cancer.

It also marked the first time researchers have pinpointed how sunbeds cause DNA mutations in the skin that make users more susceptible to cancer.

More than 80 percent of the most common melanomas are caused by exposure to ultraviolet radiation, according to the World Health Organization’s International Agency for Research on Cancer (IARC).

These rays are created naturally by the Sun — or artificially by tanning beds.

Skin cell damage

Pedram Gerami, a dermatologist and researcher at Northwestern University in Illinois, told AFP he started looking into this subject after an “unusually” high number of younger women came into his clinic with multiple melanomas.

The cancer was also on parts of their bodies normally “relatively protected from the sun,” said the study’s author.

His team compared the medical records from 3,000 people who used tanning beds to those of similarly aged people who had not.

Melanoma was diagnosed in five percent of the tanning bed users, compared to two percent of the other group, the study said.

After adjusting for a variety of factors such as age, sunburn history and family history, the researchers estimated tanning bed users were nearly 2.9 times more at risk of getting a melanoma.

Tanning bed users were also more likely to develop melanoma on parts of their body that are normally shielded from the Sun, such as the lower back and buttocks.

The researchers also sought to find out how much damage tanning beds do to the DNA of skin cells, because it can build up into cancer.

They sequenced 182 biopsies, including one from Gerami’s patient Tarr.

New technology was used to specifically look at melanocytes, which are rarer skin cells that create moles — or melanoma.