If there were a sunscreen-off between the two different kinds of sunscreen — mineral and chemical — we’d put our money on mineral every time. The mineral in question? Zinc oxide. Here’s why: It’s a physical barrier, sitting on top of the skin and scattering, reflecting or absorbing harmful UVA and UVB rays. Way better than chemical sunscreens with potentially harmful ingredients absorbing into your body, right?
That’s what the FDA — and other top scientists — think. In fact, zinc oxide and titanium dioxide are the only sunscreen ingredients labeled Generally Regarded As Safe and Effective by the FDA (you may have seen this referred to as GRASE). Cool. But that’s not ALL you need to know! Hang on. We’re going to get all science-y for a second.
*Puts on white lab coat, fake glasses and puts hair in messy bun
Now, let’s talk about the SIZE of the minerals used in sunscreen. Because those minerals can show up in your sunscreen in two ways: in nano form (teeny tiny particles smaller than 100 nanometers), or non-nano form (particles bigger than 100 nanometers). And when it comes to mineral sunscreen, size matters.
Why? Well, when we talk about anything this small, the properties of the particle can change, becoming less stable and more chemically reactive. And tricky, if you ask us. A particle that minute can penetrate cell walls, breach the blood-brain barrier, and slip into the lungs. And. The smaller the particle, the more it reacts to UV radiation, forming free radicals — essentially cellular waste that can build up and cause damage over time. (You’ve heard about free radicals. Aside from being a sweet band name, free radicals are responsible for…yep, you guessed it: wrinkles. Oh, and skin cancer.)
So the punchline is: the bigger the particle, the better. At least for sunscreen (because sometimes, doctors prescribe transdermal medicine intended to be absorbed into your body). In this case, we want the mineral to do its job: sit on the skin and protect it — not potentially get absorbed into the skin so they can do who knows what. We bolded “who knows what” because it’s the key: several studies have shown that zinc oxide and titanium dioxide nanoparticles don’t penetrate healthy skin below the dermal layer in significant amounts. But here’s the rub: nanoparticles are unpredictable. They misbehave. Not much is known about them, and, unlike the EU and Australia, the US has yet to create specific guidelines and regulations around their use.
To quote the FDA, “In summary, nanomaterials can have chemical, physical, and biological properties that differ from those of larger scale particles with the same chemical composition, and the use of nanomaterials in cosmetic products may raise questions about the safety of the product for its intended use … We expect that the science surrounding nanomaterials will continue to evolve and be used in the development of new testing methods.”
Translation: when it comes to nanomaterials, we don’t really have the answer yet.
So…why mess with them?
What is abundantly clear is this: there’s significant evidence of harm when nanoparticles are inhaled in large doses (or swallowed for that matter, so make sure to read the ingredients of that lip balm with sunscreen). In fact, titanium dioxide, when inhaled, is a possible carcinogen. We’re talking about powder and spray sunscreen or makeup, friends. You don’t want to inhale that stuff.
WHAT ABOUT CLEAR MINERAL SUNSCREENS?
Non-nano mineral sunscreens work well because they show up white — which reflects all the visible wavelengths in the color spectrum. If your sunscreen is sheer or clear, it’s most likely made with nano particles, which appear to clump together and make absorption less likely. So while yeah, clear mineral sunscreen doesn’t make you look white, they’re still made with nanoparticles. Which are…what? Unpredictable. That’s right, class.
Over at Earth Mama, we like to know how our active ingredients are going to … well, act, which is why we stick to non-nano zinc in our sunscreen. Plus, we’d rather you stay safe. Ok? Ok. Annnnd…that concludes today’s science lesson.
*Takes glasses off, shakes out hair with a good hair toss, removes lab coat and liberally applies non-nano mineral sunscreen. The end.