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Stanford University School of Medicine

Stay sun-safe this summer with these sunscreen tips

summer-635247_1920Bombarded by an array of sunscreens, it's tricky to figure out which one is both safe to use and protective against harmful sun exposure. Never fear: Writer Sara Wykes took the time to sort through the snarl of sunscreens with dermatologist Susan Swetter, MD, who directs the Pigmented Lesion and Melanoma Program at the Stanford Cancer Institute.

In a 5 Questions feature in the current issue of Inside Stanford Medicine, Swetter defines terms such as "SPF" and "broad-spectrum" and breaks down myths related to "natural" sunscreens. For example:

Sun protection factor, or SPF, was originally designed to measure sun protection from ultraviolet B rays, the primary cause of sunburn and skin cancer. Only in recent years has research shown that exposure to ultraviolet A rays is equally damaging to the skin, and its harmful effects have been seen in people exposed to high amounts of UVA and UVB radiation in indoor tanning booths. Without the warning signs of sunburn, UVA radiation penetrates the skin more deeply than UVB rays. UVA radiation contributes to skin photoaging -- discoloration, wrinkling and sagging of the skin. It also passes through the ozone layer, clouds and window glass. UVA rays are also more plentiful than UVB because they are strong throughout the day and the year. While SPF values are generally easy for consumers to understand, they are not a good measure of UVA protection.

This is a timely topic, as Consumer Reports recently found that 40 percent of sunscreens labeled SPF 30 or higher didn't provide the printed level of protection. Here's Swetter:

Consumer Reports reported that physical sunscreens (also called "natural," "mineral" or "organic") were the ones most likely to fail the SPF accuracy test. The active UV filtering ingredients for those products are typically micronized titanium dioxide or zinc oxide (or both). These do work to protect against UVB, but have a low SPF in themselves... In general, chemical sunscreens provide UV filtration that is superior to that of physical sunscreens The most appropriate use of physical sunscreens is for children under age 2 and adults and children who have skin allergies to chemical sunscreens.

Swetter goes on to recommend using chemical sunscreens that contain avobenzone and octocrylene. And here's a parting word from her: "Apply often. This approach should go a long way to preventing sunburn and skin cancer, including the most deadly form, melanoma."

Previously: It's never too early to protect your skin from sun damageWalking on sunshine: How to celebrate summer safely and This summer's Stanford Medicine magazine shows some skin
Photo by jill111

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