Volume 13, Number 4: July 2005
Ask Dr. Nancy
Nancy VanVessem, M.D.
Chief Medical Officer, Capital Health Plan
Q: I'm concerned and confused about tanning. What are UVA and UVB rays? Is it true that UVB is the "bad" light that burns?
A: First, there is no safe UV (ultraviolet) light, which is the sun's invisible light, and therefore no safe tan. Both ultraviolet-A (UVA) and ultraviolet - B (UVB) are radiation and cause suntan, sunburn, and sun damage. In short, they break down the DNA, which is the genetic material in your skin. When the skin repairs itself, mistakes can be made which leads to skin cancer. That's why so many skin cancers show up on sun exposed areas like the face. Your skin responds to the damage by tanning. A tan is not a sign of health but of hurt. The invisibility of all UV lights means you can tan and burn on a cloudy day. The most common skin cancers are basal cell and squamous cell cancers. Repeated UV exposure leads to more and more damage. That's why it's not uncommon to see older people with multiple skin cancers.
Melanoma is a much more serious skin cancer which is becoming more common, and if not caught at its early stages, can lead to death. New research shows that even one extensive sunburn after age 20 increases two-fold an adult risk of melanoma, the deadliest skin cancer. Researchers already knew that sun exposure before 18 significantly increases skin-cancer risk later in life, especially melanoma. If you want more information about melanoma- go to CHPConnect, click on Healthwise®, then go to the melanoma section. There you can find out what to watch out for on your own skin or the skin of your children. There is also basic information about prevention and diagnosis skin cancer in general.
While some sunlight is necessary for health, Floridians receive plenty, even when wearing sunscreen. Overexposure during our lives can cause - in addition to skin cancer - premature skin aging, cataracts, allergies, and damage to the immune system.
Use these precautions in the sun:
Use a broad-spectrum sunscreen (blocks both UVA and UVB) with an SPF (sun protection factor) of at least 15. Apply generously. Infants under six months are best kept out of the sun, but you may use a small amount of sunscreen. Apply 20 minutes before going into the sun. Reapply after swimming or heavy sweating. Reapply every 1 1/2 hours otherwise. Wear a broad-brimmed hat, sunglasses that protect against UV rays, and tightly woven clothing. A typical white T-shirt has an SPF of only 3. Avoid the sun between 10 am and 4pm.
Email your wellness question to leadams@chp.org and put "Dr. Nancy" in the subject line.