What Are Nanoparticles in Sunscreen?

Woman applying sunblock protection on shoulders

You've decided that using a natural sunscreen is the right choice for you. Maybe you feel it's the healthier choice for you and the environment, or sunscreen with synthetic active ingredients irritate your oh-so-sensitive skin.

Then you hear about "nanoparticles" in some natural sunscreens, along with some alarming and conflicting info about said particles that gives you pause. Seriously, does choosing a natural sunscreen have to be this confusing?

With so much info out there, it can seem overwhelming. So, let's cut through the noise and take an unbiased look at nanoparticles in sunscreen, their safety, reasons why you'll want them in your sunscreen and when you won't.

What Are Nanoparticles?

Nanoparticles are incredibly tiny particles of a given substance. Nanoparticles are less than 100 nanometers thick. To give some perspective, a nanometer is 1000 times smaller than the thickness of one strand of hair.

While nanoparticles can be naturally created, like minuscule droplets of sea spray for example, most nanoparticles are created in the lab. For sunscreen, the nanoparticles in question are zinc oxide and titanium dioxide. These ingredients are broken down into ultra-fine particles before being added to your sunscreen.

Nanoparticles first became available in sunscreens in the 1980s, but didn't really catch on until the 1990s. Today, you can assume your natural sunscreen with zinc oxide and/or titanium dioxide are nano-sized particles unless specified otherwise.

The terms "nano" and "micronized" are synonymous. So, sunscreen bearing a "micronized zinc oxide" or "micronized titanium dioxide" label contains nanoparticles.

Nanoparticles aren't just found in sunscreens. Many skincare and cosmetic products, like foundations, shampoos, and toothpaste, often contain micronized ingredients. Nanoparticles are also used in electronics, fabrics, scratch-resistant glass, and more.

Nanoparticles Keep Natural Sunscreens From Leaving a White Film on Your Skin

When choosing your natural sunscreen, you have two options; those with nanoparticles and those without. The difference between the two will show up on your skin.

Both titanium dioxide and zinc oxide are approved by the FDA as natural sunscreening ingredients. They each give broad-spectrum UV protection, although titanium dioxide works best when combined with zinc oxide or another synthetic sunscreen ingredient.

Zinc oxide and titanium dioxide work by reflecting UV rays away from the skin, shielding the skin from the sun. And they're very effective.

In their regular, non-nano sized form, zinc oxide and titanium dioxide are quite white. When incorporated into sunscreen, they'll leave an obvious opaque white film across the skin. Think of the stereotypical lifeguard with white across the bridge of the nose—yep, that's zinc oxide.

Enter nanoparticles. Sunscreen made with micronized zinc oxide and titanium dioxide rub into the skin much better, and won't leave behind a pasty look. The ultra-fine nanoparticles make the sunscreen less opaque but just as effective.

The Vast Majority of Research Finds Nanoparticles in Sunscreen Safe

From what we know now, it doesn't seem that nanoparticles of zinc oxide or titanium dioxide are harmful in any way. However, the long-term effects of using micronized zinc oxide and titanium dioxide, is a bit of a mystery. In other words, there is no proof that long-term use is completely safe, but there's no proof it's harmful either.

Some have questioned the safety of these micronized particles. Because they are so small, they can be absorbed by the skin and into the body. How much is absorbed and how deeply they penetrate depends on how small the zinc oxide or titanium dioxide particles are, and how they are delivered.

For kicks, what happens to your body if zinc oxide or titanium dioxide nano-particles are absorbed? Unfortunately, there's no clear-cut answer for that, either.

There's speculation that they may stress and damage our body's cells, accelerating aging both inside and out. But more research needs to be done to know definitively one way or another.

Titanium dioxide, when in its powdered form and inhaled, has been shown to cause lung cancer in lab rats. Micronized titanium dioxide also penetrates the skin much more deeply than micronized zinc oxide, and titanium dioxide has been shown to pass through the placenta and bridge the blood-brain barrier.

Remember, though, that much of this info comes from ingesting titanium dioxide (since it's found in many prepackaged foods and sweets). From the many studies of topically applied micronized titanium dioxide and zinc oxide, only occasionally are these ingredients found in the skin, and even then they were in very low concentrations.

That means that even if you apply a sunscreen containing nanoparticles, they may not even absorb past the first layer of skin. The amount absorbed varies greatly depending on the formulation of the sunscreen, and much of it won't absorb deeply if at all.

With the information we have right now, sunscreen containing nanoparticles appears to be safe and very effective. Less clear is the effect long-term use of the product may have on your health, especially if you're using the product daily. Again, there's no proof that long-term use of micronized zinc oxide or titanium dioxide is harmful, we just don't know what effect it has (if any) on your skin or body.

A Word From Verywell

First, remember that wearing sunscreen every day is one of the best things you can do for the long-term health of your skin (and it's the best anti-aging method too). So, kudos to you for being proactive in protecting your skin!

There are so many natural sunscreens available, both nano and non-nano options, there's definitely a product out there for you. Using a sunscreen with micronized (AKA nano-particle) zinc oxide or titanium dioxide will give you a product that is less pasty and rubs in more fully.

If your concerned about nano-particles, using a non-micronized sunscreen will give you larger particles that are less likely to be absorbed by your skin. The trade-off is you'll notice a white film on your skin after application.

Another option if you are concerned is to avoid micronized titanium dioxide products altogether, since this ingredient is the one that has been linked to possible heath problems. Remember, though, that most of these problems were from inhaling or ingesting titanium dioxide nanoparticles, and not from skin absorption.

Natural sunscreen, both micronized and not, vary greatly in their consistency and feel on the skin. So, if one brand isn't to your liking, try another until you find the one that works for you

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

By Angela Palmer
Angela Palmer is a licensed esthetician specializing in acne treatment.