The Truth About Sunscreen Claims

Top docs weigh in on two scary rumors about sunscreen

by Jennifer Scruby
women applying sunscreen image

1. The claim: Your sun-protection lotion starts to degrade the second you step into the sun—and wearing this compromised formula may cause you to suffer the same free radical damage you’d get from unprotected UV exposure.

The truth: “This information comes from a small, isolated 2006 study,” says dermatologist Deborah S. Sarnoff, senior vice president of the Skin Cancer Foundation. Turns out the research tested sunscreen formulas that are now mostly obsolete. “In the past, some sunscreens were not photo stable, meaning they’d gradually break down and release free radicals when exposed to UV light,” says Sarnoff. Today, however, under new FDA rules, all sunscreens labeled “broad spectrum” must show proof of photo stability. Sarnoff warns, though, that even photo stable formulas are ineffective after 90 minutes of UV exposure, so reapplication is still key.

2. The claim: A form of vitamin A (retinyl palmitate, an antioxidant found in a quarter of all sunscreens) can speed tumor growth in skin exposed to UV light.

The truth: “This is based on one FDA study in which mice were treated with a vitamin A cream and exposed to direct sunlight,” says Joshua Zeichner, MD, assistant professor of dermatology at Mount Sinai Medical Center. “But—and this is key—the mice weren’t wearing sunscreen, so they got fried.” In fact, there’s evidence that oral medications derived from vitamin A may help prevent skin cancer. “They are sometimes used off-label to slow the development of skin cancer,” Sarnoff says. “Retinyl palmitate in sunscreen is fine.”

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First Published Fri, 2013-04-05 11:08

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