Safety of titanium dioxide nanoparticles in cosmetics.

Nano-titanium dioxide (the tiny particles used in sunscreens and foundations) doesn't penetrate beyond your skin's outer layer and doesn't enter your bloodstream—even in damaged skin. The EU's safety committee found no evidence it causes cancer, genetic damage, or reproductive harm when applied to skin at concentrations up to 25%. The one caveat: it shouldn't be used in sprays or powders because inhaling it could potentially cause lung inflammation in animals, though human data is limited.