Sun Exposure
Nina Radford, M.D.

Sunlight is made of two kinds of ultraviolet or UV radiation: UVA rays and UVB rays. While UVB rays are the primary cause of sunburn and skin cancer, UVA rays also contribute. Although glass windows block UVB rays, they do not block UVA rays; so spending long stretches of time in front of a sunny window may have adverse effects on skin health as well. Both kinds of UV rays also pass through overcast skies and through water; so a day in the pool under a cloudy sky is not without sunburn potential.

The most serious side effect of sun exposure is skin cancer. Almost half of all Americans will have skin cancer at least once during their lives. Although anyone can get skin cancer, the risk is greatest for people who have fair skin that freckles easily, who expose themselves frequently to natural and artificial sources of UV light, such as tanning booths, or live in areas that get high levels of UV radiation such as Texas or Florida.

The three common types of skin cancers are basal cell carcinoma, squamous cell carcinoma and melanoma. Basal cell carcinomas account for the overwhelming majority of all skin cancers. They are found on areas of skin that are frequently exposed to the sun such as the neck, face and hands. Squamous cell cancers are also found primarily on sun-exposed areas. These two types of cancer are slow growing and rarely spread. The most dangerous of skin cancers is melanoma because it can spread.

Melanoma begins in cells called melanocytes that make a substance called melanin. Melanin is a pigment that causes the skin to turn brown after sun exposure. Melanoma cancer cells continue to make melanin, which is why these cancers may appear multicolored with tan, brown and black coloring. However, melanoma cancers can also be red or white.

While melanoma can occur suddenly, in any part of the body, it can also begin near or in a mole. That is why it is important to report a change in the appearance of a mole to your health care professional. The American Academy of Family Physicians has formulated the "ABCDE" rule to help you identify moles, which may need further evaluation. When looking at moles on your skin, look for the following:

A- Asymmetry: both sides of a mole don't look the same.
B- Border: The edges of a mole are blurry or jagged.
C- Color: a mole changes color or is multi-colored.
D- Diameter: a mole is larger than the size of a pencil eraser tip.
E- Elevation: a mole is raised above the skin and has a rough surface.

The best way to keep your skin healthy is to avoid exposure to UV rays. Because so much of our lifetime sun exposure happens during our childhood and early adult years, these are critical strategies to implement for the whole family.

Stay out of the sun. Avoid the sun between 10 a.m. and 4 p.m. when the sun's UV rays are strongest.

Use sunscreen. Sunscreens are rated in strength according to a sun protection factor. Buy products with an SPF number of 15 or higher. The water resistant formulations are a must if you get wet or sweat a lot. Remember to reapply the lotion as needed. Choose products with "broad UV spectrum" protection, such as those containing zinc oxide, titanium dioxide, or Parsol 1789.

Wear protective clothing. Protective items include a wide brimmed hat to protect neck, head and ears, sunglasses and loose, lightweight clothing to cover arms and legs. Choose sunglasses that block both UVB and UVA rays; wearing sunglasses can protect your eyes from cataracts.

Avoid artificial UV rays. Don't use sunlamps and tanning beds.

Check your skin often. Look for changes in the size, shape, color, or feel of birthmarks, moles, and spots. Warning signs can also include a mole that bleeds or itches or a sore that won't heal or feels crusty. The American Academy of Dermatology suggests that older, fair-skinned people have a yearly skin check by a doctor as part of a regular physical exam.

For more information, contact:
National Institute of Arthritis and Musculoskeletal and Skin Diseases Clearinghouseat 301-495-4484 or http://www.nih.gov/niams/

National Cancer Institute at 1-800-422-6237 or http://www.nci.nih.gov/

The American Academy of Dermatology at 1-888-462-3376 or http://www.aad.org/

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