by Stephen Q. Wang, MD
There is a pervasive belief in our culture that a tan connotes health, affluence and even beauty. This can be seen in fashion magazines and the entertainment media. The tanning industry itself is much more vocal, blatantly and systematically promoting the “benefits” of tanning. A frequent message from the industry is that a tan offers protection against sunburn. Although the message has an intuitive appeal, scientific studies have proved it false. A tan generated by ultraviolet (UV) exposure offers, at best, a very low level of protection against sunburn.
A study examining the effects of tanning was carried out by Cripps in 1981. The investigators found that tanned skin offered sun protection factors (SPFs) of just 2.4, 2.5 and 2.1 for individuals with Fitzpatrick skin types II, III, and IV, respectively. Later studies reported that a tan offered an SPF of only between 2 and 3. It’s clear that a tan induced by UV exposure plays a mini- mal role in protection against sunburn; an SPF of 15 or higher is required for proper protection.
A Dangerously Misleading Message
In view of this, the tanning industry’s message that a tan offers protection against sunburn is irresponsible and dangerous. Individuals hearing this suggestion might visit tanning salons to obtain a baseline tan before vacationing in sunny climates. With a baseline tan, these individuals would have a false sense of security. They might stay out in the sun longer, and neglect to seek the shade or use sunscreen. Because the amount of protection provided by the tan is so small, they could get burned. More importantly, prolonged UV exposure can lead to DNA damage, a suppressed immune system and photoaging, even in the absence of a sunburn.
Tanning Means DNA Damage
The nominal protection supplied by a baseline tan is only one part of the problem. What is even more alarming is new research revealing the mechanisms and triggers for melanogenesis (the proliferation of melanocytes, the pigment cells where melanoma forms) and tanning due to UV exposure. UV harms the skin cells’ DNA. To preserve the integrity of the genetic code, repair enzymes are activated almost immediately to correct the damage. In cells where extensive or irreparable injury occurs, these cells switch on the pathway for controlled self-destruction (apoptosis). Extensive data demonstrate that DNA damage or DNA repair intermediates are powerful signals that initiate melanogenesis. In some studies, investigators demonstrated this by inducing tanning with topical applications of DNA fragments. In addition, maintenance of a tan requires ongoing UV exposure, which is associated with continual DNA photodamage. The current thinking is that tanning is a biological signal by the skin that reflects the presence of DNA impairment.
So is a tan ever a good thing? From a health perspective, certainly not! The low level of photoprotection afforded by a tan is far outweighed by the damage incurred in its development and maintenance. For those who prefer tanned skin, using a non-UV self-tanner is an alternative. However, this is only a temporary solution and it is important to continue to use sunscreen. A broader change is needed. We must change our culture’s unhealthy misconception that tanned skin is a sign of health and beauty.
Dr. Wang is Director of Dermatology and Dermatologic Surgery, Memorial Sloan-Kettering Cancer Center at Basking Ridge, NJ. He is also a member of The Skin Cancer Foundation’s Photobiology Committee.
Published on November 17, 2011