Should I Be Worried About Micro- or Nanoparticles in My Mineral Sunscreen?
Two dermatologists weigh in on whether the minuscule particles present any risks.
You've heard the rallying cries of dermatologists and beauty professionals far and wide: Using a sunscreen on your face is a necessary daily ritual to prevent UV-inflicted damage and to ward off premature wrinkles and fine lines. But as recent studies have shown, the actives in chemical-based sunscreen formulas—such as oxybenzone and octocrylene—can absorb through the skin and enter the bloodstream. This is why many turn to mineral-based options, made with zinc oxide, titanium dioxide, or some combination of the two.
There's another good reason for this. "Those with sensitive skin tend to fare better with these types, as they're less likely to cause an allergic reaction or irritation," says New York-based dermatologist Julie Karen, member of the Skin Cancer Foundation. The problem? Historically, they've been thick and chalky—but companies have recently re-formulated, infusing their sunscreens with skincare ingredients and flattering tints. They've also shrunk the size of the zinc oxide and titanium dioxide particles, so that they blend in more easily upon application. This has led some to questions on whether or not these tiny mineral particles—microparticles, and particularly, nanoparticles (the extra-small ones, with a diameter less than 100 nanometers long)—can actually seep into the skin, which would ultimately pose a potential health risk.
Thanks to a host of new studies on both titanium dioxide and zinc oxide over the past few years, however, we know that microparticles cannot penetrate the skin—and we're now also aware of the fact that the vast majority of nanoparticles cannot do so, either (the most penetration observed was 0.01 percent of the applied dose, which isn't a statistically significant result). Dermatologists like California-based Lisa Chipps are hoping to nix the misconceptions surrounding mineral-sunscreen absorption: "Based on the data, we know that the benefits of wearing the sunscreen far outweigh any potential dangers." In fact, for both Dr. Chipps and Dr. Karen, new formulations with smaller-sized particles are a boon. "They're far more elegant to apply and wear," says Dr. Karen, "which increases adherence and compliance among my patients." So long as you're selecting an SPF 30 broad-spectrum option, the best mineral sunscreen for you is the one you enjoy wearing, say both dermatologists.
As for proper application? In the mornings, after washing your face and applying any skincare products, use a nickel-sized amount of sunscreen for your face and the tops of your ears, advises Dr. Karen. If you wear makeup, that should go on after the sunscreen—and it's a bonus if your foundation contains SPF, too (though you shouldn't rely on that for your full daily protection). If you'll be outside for more than two hours, plan on reapplying, either using the same product you started with or by dusting on a substantial coating of a powder SPF atop your makeup, like Colorescience Sunforgettable Total Protection Brush On Shield SPF 50 ($65, dermstore.com) or Jane Iredale Powder Me SPF 30 Dry Sunscreen ($47, janeiredale.com).