Question: What are nanoparticles in sunscreen?


The dilemma with sunscreens today is that sunscreens that feel good on the skin (i.e. aren't greasy, heavy, etc.) usually don't offer the best protection and sunscreens that offer the best protection usually don't feel that great. This occurs because sunscreen actives all have different properties.

A physical UV blocker like zinc oxide has great stability, low skin irritation, and protects well against UVA and UVB rays. However, it is also thick, white, and heavy, so a sunscreen with those qualities will just not be as cosmetically elegant. It will feel heavy on the skin and when you apply the right amount in order to get the best protection, it might leave your face with a white cast.

Therefore, sunscreen manufacturers are continually trying to make the most protective and cosmetically elegant sunscreen. To achieve this seemingly impossible coexistence, they have turned to using zinc oxide and titanium dioxide nanoparticles. Zinc oxide and titanium dioxide nanoparticles are exactly what they sound like they are - super small, nano-sized zinc oxide and titanium dioxide.

Nanoparticles and Sunscreens

Sunscreens with these nanoparticle agents are also known as nano-sunscreens or nanotechnology sunscreens. The nanoparticles themselves are often referred to as nano-ingredients, nanoscale zinc and titanium, nano zinc, or nano titanium. Smaller particle sized sunscreens may also be called micro-mineral sunscreens, ultra-fine sunscreens, or micronized sunscreens. The smaller particles themselves can be labeled as micronized zinc, micronized titanium dioxide, or micro-sized particles.

(Note: "Nano" and "micronized" sunscreens are often grouped together. When nanoparticles first started being used in sunscreen, skin care companies jumped on the new trend. But when safety concerns about nano sunscreens surfaced (more on that below), skin care companies sought to distinguish their smaller particle sized sunscreens (if they weren't nanosunscreens) from nanoparticles by calling them "micro" or "micronized" sunscreens. Theoretically, micro-sized particles are bigger than nano-sized particles and therefore not a safety issue since micronized particles are less penetrating to the skin. However, some studies have shown there to be nanoparticles in sunscreens that claim to only have micronized particles, so things are still questionable.)

Regular zinc oxide and titanium dioxide UV filters are already stable, offer good sun protection, and generally don't cause any skin irritation. The main complaint with these physical UV blockers is that they just don't feel or look good on skin. This is why the actives are being micronized. Zinc oxide and titanium dioxide nanoparticles tend to leave much less white residue than regular zinc oxide and titanium dioxide while still retaining the ability to protect against UVA and UVB rays in their respective ranges.

So what's the problem with them?

Safety Concerns about Nanoparticles in Sunscreen

The problem with zinc oxide and titanium dioxide nanoparticles is that they may promote the generation of free radicals when exposed to sunlight, which damage and age your skin. More research must be done on this, but the nanoparticles are usually coated, or microencapsulated, with a strong substance to decrease this kind of reaction.

The other safety concern about nanoparticles in sunscreen is how much of the nanoparticles are being absorbed by your skin. Because of their miniscule particle size, potentially unsafe amounts of zinc oxide and titanium dioxide nanoparticles may make their way into your bloodstream and body organs from your skin. Research seems to show that nano zinc is somewhat safer than nano titanium though. Zinc nanoparticles appear to be processed like a zinc supplement, however how titanium dioxide nanoparticles are processed remains unknown. There is no conclusive evidence yet, so more research must be done.

Because the technology in using nanoparticles in sunscreen is so new and because there are potential safety risks associated with these nanoparticles, it is probably best to stay away from sunscreens with these nano-sized and micronized actives until their safety of use can be definitively determined.

Nanoparticle actives in sunscreen usually refer to nanoparticle sized zinc oxide and titanium dioxide. They are the next generation of sunscreen UV actives, but whether or not they will replace regular zinc oxide and titanium dioxide as commonplace UV blockers is still to be determined.

Last updated: September 14, 2012

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