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 can also be found in dairy products to make them whiter and brighter … like frosting or cottage cheese, Stoiber told USA TODAY, adding that the additive is used in other products – such as food or beverage instant mixes – as an anti-caking agent.