How does zinc oxide sunscreen work?

On February 2019, the FDA recommend the GRASE (generally recognized as safe and effective) status on only two active ingredients for use in sunscreen: zinc oxide and titanium dioxide. The FDA also requested further research on the remaining active ingredients including oxybenzone and octinoxate) before they can be listed as safe in the United States.

 

The Most Effective Sunscreen Ingredient

Zinc oxide scatters, reflects and absorbs UV rays and converts the energy to infrared heat, which radiates safely away from the skin surface. It’s the most effective sun protector available, blocking out both shorter and longer wave UVA rays as well as all UVB rays.

In this respect, zinc oxide is a better than titanium dioxide (across a greater range of UVA wavelength). In fact, zinc oxide is the only active sunscreen ingredient that covers the entire UVA/UVB spectrum and even UVC by itself.

Non-nano zinc oxide has the broadest UV absorptive spectrum and cannot be absorbed into the blood, unlike all petroleum-based sunscreen chemicals.

 

Zinc Oxide is Misunderstood

Zinc oxide is, however, fairly misunderstood within the skincare industry. Most manufacturers, dermatologists and popular media outlets report that zinc oxide reflects and scatters UV radiation, an understandably common sense assumption due to its white color.

However, although zinc oxide LOOKS white because it does indeed reflect and scatter VISIBLE light, it behaves entirely differently in the UV spectrum of light, which is NOT visible to humans.

In fact, zinc oxide absorbs UV radiation via a process called band-gap absorption, then converting it into comparably harmless infrared energy, which it disposes of as heat.

In contrast, while titanium dioxide absorbs UV, it cannot convert it as easily into heat, instead dumping the absorbed energy on nearby electrons and creating free radicals that cause oxidative damage throughout the body.

 

 

Ask us anything!

Email Mac questions about sunscreen, skincare or anything outdoors > mac@gowaxhead.com

 



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