Titanium dioxide has been used as a bleaching and opacifying agent in porcelain enamels, giving them brightness, hardness, and acid resistance. In modern times it is used in cosmetics, such as in skin care products and sunscreen lotions, with claims that titanium dioxide protects the skin from ultraviolet radiation because of its property to absorb ultraviolet light.

French researchers studied how and where E171 nanoparticles enter the bloodstream, first studying the route through pigs and then in vitro with human buccal cells, for a 2023 study published in the journal Nanotoxicology. The research showed that the nanoparticles absorbed quickly through the mouth and then into the bloodstream, before damaging DNA and hindering cell regeneration.

Mars Wrigley, the company that makes Skittles, is being sued by a California man who claims the candy contains a known toxin that poses such a serious health risk that Skittles are unfit for human consumption.