There’s science inside that tube of sunscreen



    If you’re spending time outside this Memorial Day weekend, your dermatologist wants us to remind you to protect yourself from the sun — even if it’s not blazing hot.

    “On hazy days, ultraviolet radiation is piercing the atmosphere and can cause a sunburn just as easily,” said dermatologist David Leffell, whose specialty is skin cancer and melanoma.

    When you’re developing a sunscreen, the Holy Grail is a product that people will actually put on.

    “The No. 1 complaint of the use of sunscreen is that it’s inconvenient, but I always say it’s not as inconvenient as having to have surgery for skin cancer,” said Leffell, professor of dermatology and surgery at Yale School of Medicine.

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    Dow Chemical in Montgomery County, Pennsylvania, developed an additive that’s used in lots of brand-name sunscreens. Materials engineer Nilesh Shah explained the technology as nearly invisible hollow spheres that are combined with basic UV filter to make them more effective.

    “The incoming light, essentially, scatters off that hole, and instead of the that light being able to go directly down to your skin, being absorbed along the way, you scatter it. You just do a much better job of absorbing the UV light and get a much higher protection factor,” said Shah, global research and development director at Dow Consumer Care.

    The trick is to increase the SPF without making the lotion feel like cake batter, he said.

    What’s new in sunscreen? Ingredients such as zinc oxide and titanium dioxide — that sit on top of the skin — are popular again, Shah said.

    “Going back to the days when you used to see lifeguards on the beach with that white paint on their nose, but without creating that white effect,” he said.

    Other innovations in sun protection are technologies that warn people when they’re getting too much sun — such as an app on your phone or an indicator sewn into your clothes. There are also colorful, stretchy patches that are supposed to measure UV exposure.

    “I’ve heard of it, haven’t seen it in action, as a scientist I want to see data before I believe it,” Shah said.

    And a final sunscreen suggestion from dermatologist David Leffell — don’t forget to reapply every couple of hours and when you come out of the water.

    “Despite what labels say, no sunscreen is truly waterproof,” he said.

    One guideline suggests that people put on at least a shot glass full of lotion, but Leffell said the right amount will be different if you are, say, 5’2 versus 6’4.

    “Apply enough to evenly coat the skin and massage it in well,” he said.

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