They are the only two sunscreen ingredients classified by the FDA as safe and effective. And though titanium dioxide is usually used in mineral sunscreens in the form of nanoparticles, evidence suggests that few, if any, particles penetrate the skin.

Titanium dioxide comes in the form of a white powder and is sometimes used in cosmetics to adjust a color to a lighter shade. This is also why it can produce a white cast.

Lithopone 30% CAS No. 1345-05-7