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Jane Varner, M.D.Jane Varner, M.D.Family MedicinePalo Alto Medical Foundation
Jane Varner, M.D.Family MedicinePalo Alto Medical Foundation

Dr. Varner's professional interests include: fitness and nutrition, menopause, diabetes and high cholesterol management, depression and anxiety, and adolescent medicine.

Question of the Week

My son is in school all day, then jumps into a car to travel to an outdoor swim practice. He has about five minutes to get ready. If we apply sunscreen in the morning, is it still effective eight hours later? What sunscreens are best for his situation?

Jane Varner, M.D. answered: I’m SO glad that your family is remembering sunscreen! The most recent statistics from the Center for Disease Control (CDC) show that approximately 70,000 people in the United States are diagnosed with melanoma each year, resulting in nearly 30,000 deaths. The biggest risk factor for developing melanoma is sun exposure.

There are two types of harmful ultraviolet (UV) rays: UVA and UVB. The UVA rays are thought to penetrate the deeper layers of the skin, causing premature aging and wrinkling. UVA rays can even penetrate window glass! The UVB rays are thought of as the “burning” rays. Broad spectrum sunscreens and sun blocks protect against both UVA and UVB rays, so be sure to look for these. Use a sunscreen or sun block with a minimum of SPF 30.

Sunscreen or sun block needs to be re-applied at least every two hours, more often if you are sweating heavily or spending time in the water. So ideally your son should reapply sunscreen just before the swim practice.

If you are spending time in the water, choose a sunscreen that is either water resistant or very water resistant (it turns out there is no such thing as water proof!). A water resistant sunscreen should be reapplied every 40 minutes and a very water resistant sunscreen should be reapplied at least every 80 minutes. You will need at least one ounce to sufficiently cover the whole body. Spray sunscreens are okay too, but make sure that the sunscreen is actually landing on the skin and not getting carried away by the wind!

Think about sun protection, regardless of cloudy skies. It is estimated that 80 percent of harmful UV rays pass through even the thickest clouds. Also remember that certain medications increase your sensitivity to the sun’s rays — be sure to check with your doctor or pharmacist if you aren’t sure.

Back to the threat of melanoma, the American Academy of Dermatology recommends that everyone “check their birthday suit on their birthday.” At least once a year, with the help of a mirror, thoroughly examine your skin using the “ABCD” criteria:

Asymmetry: One half of the mole looks different from the other half.
Border irregularity: The edges are ruffled and uneven.
Color: The color is uneven, with dark brown and even black segments present.
Diameter: Larger than 6mm, or about the size of a pencil eraser.

If you are worried about the appearance of a mole, be sure to consult with your family doctor and/or dermatologist…it’s always better to be safe!

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