I drove past Planet Fitness on the way to my 10-year-old’s gymnastics class and had to chuckle at their sign advertising free pizza as part of a new member promotion. I decided to use this as a teaching moment, explaining to my daughter why we should avoid using junk food as a reward for exercise. This is one of many lectures she has heard from her mom, a cancer prevention scientist.

When I decided to look a little deeper into what gyms are offering to entice people to sign up, pizza turned out to be the least of my concerns. Many gyms offer access to tanning beds, a known carcinogen, to their patrons. We would be astounded if gyms provided tobacco to patrons, so we must pose serious questions to gyms who provide ultraviolet radiation.

The comparison of tobacco and tanning beds might seem like hyperbole, but it is not. They are both rated group 1 carcinogens and research shows that we now have more cancers related to tanning beds than cancers related to tobacco.

Gyms are supporting the tanning industry

To explore how pervasive these gym-tanning salons were, I asked my research assistant to call every Planet Fitness, Anytime Fitness and Gold’s Gym in Massachusetts and Connecticut to find out just how many had tanning beds. Of the 167 gyms we found on Google, 66 percent offer patrons tanning beds, with Planet Fitness the biggest offender where a whopping 100 percent of their franchises have tanning beds. In total, these gyms have 408 tanning beds. Extrapolating this to all 50 states would mean that these three gym chains alone house over 10,000 tanning beds nationwide. That’s an equivalent capacity to 1,600 tanning salons. The tanning industry must be thrilled.

Making the presence of tanning beds in gyms even more shocking is a recent study showing that people who are physically active are at increased risk for melanoma, the deadly form of skin cancer. Tanning bed use is a major risk factor for melanoma, which is now the third most prevalent cancer in women under 49 years old, a popular gym demographic. Why would we put a carcinogen in the facility frequented by people who are at increased risk for the very cancer it causes?

I decided to conduct a study to learn more about people who use those gym tanning beds. We surveyed 636 people who have ever used a tanning bed in their life and found that about a quarter of them had tanned in gyms. When I compared the group who had tanned in a gym to the group who had not, I was surprised to find that the gym tanner is a much harder core tanner. They hit the tanning bed 67 percent more often than other salon tanners and were far more likely to report tanning addiction. Gyms seem to be a great place for tanners to get their fix.

We also found in our sample of tanners that more tanning was associated with more exercise. Now we may be onto why gyms provide tanning beds – people who tan a lot love to workout.

Undermining public health messaging

We do not know why tanning and exercise is linked so I can only speculate. Both activities are driven by a desire to look and feel better. Regardless, gyms that provide tanning beds reinforce the idea that tanning is part of a beauty regimen, and perhaps even worse, that tanning is part of a healthy lifestyle. Tanning is part of neither. It will destroy your skin and has the potential to completely destroy your health. For decades public health campaigns have attempted to dismantle the popular misconception that tanned skin is a sign of good health.

Tanning is a sign the body is receiving too much cancer-causing ultraviolet radiation. It is a warning sign.

Gyms should not provide tanning beds to patrons. Removing tanning beds from gyms surely won’t stop everybody from tanning, but that is certainly no argument for making them convenient for people at higher than average risk of melanoma. By pairing exercise with tanning beds, gyms undermine public health messaging and contribute to the cancer risk of their patrons. If you are joining a gym to get healthy, my advice is: pick one that has your back.

Sherry Pagoto receives funding from the National Institutes of Health.