Center for Research on Ingredient Safety

What are the active ingredients found in mineral sunscreens?

Mineral-based sunscreens use titanium dioxide, zinc oxide or these ingredients in combination to provide sun protection.

How do titanium dioxide and zinc oxide work as sunscreens?

Both titanium dioxide and zinc oxide function as sunscreens by reflecting and scattering ultraviolet (UV) radiation. This means that when UV rays hit your skin, these mineral particles bounce the rays away, preventing them from penetrating deeper into the skin, where they can cause damage.

• Zinc Oxide: It is effective in blocking both UVA and UVB rays. UVA rays are longer in wavelength, penetrate deeper into the skin, and are primarily responsible for aging and long-term skin damage. UVB rays are shorter in wavelength, affect the skin's surface, and are primarily responsible for sunburns. Zinc oxide covers the entire spectrum of UVA and UVB rays, making it a comprehensive choice for broad-spectrum protection.

• Titanium Dioxide: It is effective against UVB and short-wave UVA rays. However, it does not cover the entire spectrum of UVA rays as effectively as zinc oxide but still remains an effective broad-spectrum sunscreen.

While formulators may use one mineral or the other in their sunscreens, they frequently combine zinc oxide and titanium dioxide to create a robust sunscreen that protects without leaving a residue.

What's the difference between nano-sized mineral sunscreen ingredients and traditional mineral sunscreens?

Both traditional and nano-containing sunscreens will effectively protect against sun exposure. However, they may look different on the skin.

• Non-Nano Particles: Traditional mineral sunscreens use larger, non-nano particles of zinc oxide and titanium dioxide. These larger particles effectively scatter UV light but leave a white cast on the skin.

• Nano Particles: Manufacturers often use nano-sized particles of these minerals to reduce the white cast and improve the texture and sunscreen application process. These smaller particles are still effective at blocking UV radiation but do so with less visibility on the skin.

Are nano-sized ingredients in mineral sunscreen harmful?

No, at the concentrations used, nano-sized titanium dioxide and zinc oxide in sunscreen—comprising 25% or less of the UV filter's weight—are not known to cause harm when applied to the skin. (1,2,3).

Nano-sized titanium dioxide and zinc oxide can help create a product that doesn't cause a white cast to the skin while still protecting against the sun's damaging rays.

How are mineral-based sunscreens different than synthetically-derived sunscreens?

While mineral and synthetically-derived sunscreens provide sun protection, our bodies absorb and process them differently.  

Our skin is an exposure route, as discussed in prior posts. While our skin generally serves as a barrier to prevent the entry of harmful pathogens and chemicals, it can sometimes absorband process topically applied ingredients.

Mineral-based sunscreens contain active ingredients titanium dioxide and zinc oxide that researchers have repeatedly studied. Based on the scientific consensus, it has been determined that these sunscreens do not pose harm to human health. So, mineral-based sunscreens received the designation as generally recognized as safe and effective (GRASE) when used as intended and do not require any further safety evaluations.  

Our skin can absorb some synthetically derived sunscreen ingredients, and these ingredients can make their way throughout our bodies.

Research shows some of the active ingredients can be detected in our bloodstream. It’s important to remember that detection doesn’t mean harm. Since there is no scientific consensus on these ingredients, scientists are researching what, if any, impact this has on our health before issuing a final safety determination.

Remember, the benefits of sunscreen far outweigh the risks.

Does mineral sunscreen expire?

Yes, most sunscreens will have an expiration date on the bottle.

If it does not have an expiration date, look for a manufactured date. If the manufactured date is within the last three years, you can safely use the product. If it was manufactured more than three years prior, it should not be used.  

Does it matter how mineral sunscreen is stored?

Yes, keeping sunscreen out of direct sunlight can help it remain safe and effective longer.  

Is mineral-based sunscreen safe for children and babies?

Mineral-based sunscreens are safe and recommended for children over the age of 6 months. It's also recommended that children wear sun-protective clothing with UPF 50+ properties to help prevent sunburns.

For babies under 6 months of age, talk with your pediatrician before using sunscreens. Clothing with UPF 50+ is a safe option for this age group, as well as keeping young babies out of direct sunlight.  

The good news.

If you choose to use a mineral-based sunscreen, you can do so knowing that the formulations available on the market are safe and effective, even if they contain nano-sized ingredients.

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