The Medical Minute: The myth of the healthy tan

May 18, 2005

By John Messmer
Department of Family & Community Medicine
Penn State Milton S. Hershey Medical Center
Penn State College of Medicine

Here comes summer. Memorial Day begins the season of the sun for many Americans who take trips to the beach, play rounds of golf, swim and have all sorts of backyard activities. Summer also is tanning season. That is unfortunate, since the lighter-skinned among us are developing skin cancer at an increasing rate. There is no such thing as a healthy tan. True, tanned skin is less likely to burn, but tanned skin is damaged skin.

Sunlight contains powerful radiation. The light we see (visible light) warms us and provides energy for plant growth. It's what we don't see that causes harm -- the sun's ultraviolet (UV) rays.

There are three forms of UV -- A, B and C. The earth's atmosphere blocks the most damaging form: UVC. But the other two, UVB and UVA, reach beyond the clouds and ozone. UV light damages DNA and impairs the skin's immune defenses. Damaged DNA can lead to skin cancer. If the skin's damaged immune system fails to destroy the cancer, it grows and may spread.

UVB penetrates more deeply than UVA, but even UVA, which is used in tanning booths, has been linked to skin cancer, including melanoma, the most dangerous form. The Environmental Protection Agency notes that one in five Americans will develop skin cancer. Melanoma incidence is increasing 7 percent per year and is the most common cancer among 25- to 29-year-olds. Any sunburn increases the chance of melanoma, particularly in childhood.

UVA and UVB also cause wrinkles and rough spots -- noncancerous changes called photo aging -- by damaging the supporting proteins in our skin. The price of today's tan is premature aging of the skin. Many of the sun worshippers of 30 years ago are spending a small fortune on skin rejuvenation treatments and plastic surgery to look as young as the small number of their peers who never tanned or burned.

It's not just light-skinned individuals who are at risk. Although darker skin is somewhat protective, it is a misunderstanding to think that getting a tan will protect the skin from the sun since damage occurs while getting the tan in the first place. Photo aging still occurs and skin cancer often is more advanced when diagnosed in darker-skinned individuals.

People receive a large portion of their lifetime sun exposure by age 18. Parents should be vigilant in protecting their children from the sun, but sun protection is beneficial even for adults. Limiting exposure to the sun's damaging rays is the best method of prevention.

UV light is most intense between 10 a.m. and 4 p.m. between April and October in northern latitudes. Don't be comforted by clouds as most of the UV passes through them. Damaging UV exposure occurs even on cool days. Check the local paper or http://www.epa.gov/sunwise/uvindex.html for the UV index for the day. The higher the number, the more protection will be needed.

Although UVA does contribute to the production of vitamin D, people need only 10 minutes of exposure three times a week to make enough. Plus people also obtain vitamin D from meat and fish and from supplements in milk and fortified cereals. So, everyone should use sun block.

Sun block is rated by sun protection factor, or SPF. The SPF says how many times longer one can stay in the sun before being burned compared to having no protection. Someone who burns after 30 minutes of unprotected exposure should be able to avoid a burn with an SPF 15 for 15 times 30 minutes or seven and a half hours. A sunscreen with SPF 15 blocks 93 percent of the damaging UV rays. The 7 percent that does pass can still cause skin aging and contribute to skin cancer. To maximize safety, one should use at least an SPF of 15 (SPF 45 blocks about 98 percent of UV) plus clothing and head covering when spending time outside.

For best protection, apply sun block to dry skin before going out to give it time to form a protective barrier. Moisture washes away even waterproof sun block so reapply it every two hours or so. Even then, try to stay in shade, for example, under an umbrella, and use a wide-brimmed hat for protection of the top of the head and ears. Remember to protect lips with sun-blocking lip balm.

Whether at the beach, a ballpark, a picnic or in the backyard, the object of sun protection is to reduce the risk of burning and cancer from the sun exposure that cannot be avoided. Since there is no safe tan, no one should intentionally stay in direct sunlight even with sun block. As the Centers for Disease Control says, "If you're tanned, you're toast."

The best advice for outdoor activity is to cover the skin with clothing that does not let light through and wear sunblock on exposed surfaces. This is critical for children and highly recommended for adults. With a few precautions the summer sun can be enjoyed without burns, or increased risk of cancer, cataracts or the telltale signs of premature aging.

(Media Contacts)

Last Updated March 19, 2009