Nano-titanium dioxide in sunscreens doesn't penetrate beyond your skin's outer layer and doesn't enter your bloodstream—even on damaged skin. It's considered safe at concentrations up to 25%. The main concern: avoid inhaling it, which is why spray sunscreens and powders containing nano-TiO2 aren't recommended, though swallowing small amounts (like from lip balm) poses minimal risk.

European regulatory scientists reviewed existing human and animal studies on nano-TiO2 safety across skin, respiratory, and digestive exposure routes, then evaluated carcinogenicity, irritation, and toxicity data to set safety guidelines.

Funding not disclosed in abstract