Safety of titanium dioxide nanoparticles in cosmetics.

Nano-titanium dioxide (the tiny particles used in sunscreens) doesn't penetrate past your skin's outer layer and doesn't enter your bloodstream, even on damaged skin. At concentrations up to 25%, it shows no evidence of causing cancer, genetic damage, or reproductive harm. The main concern: avoid inhaling it, so skip nano-TiO2 in spray sunscreens and powders—but creams and lotions are considered safe.