Lyophilized vitamins@P25TiO₂NPs were obtained through the described methods with excellent reproducibility and yield: over 99% of initial P25TiO₂NPs were functionalized.

The most significant uncertainty identified by the EU experts was the concern that TiO₂ particles may have genotoxic effects. Genotoxicity refers to the ability of a chemical to directly damage genetic material within a cell (DNA), which may lead to cancer in certain situations. Although the experts did not conclude that TiO₂ particles in E171 are genotoxic, they could not rule out the concern that they might be.

1. What is titanium dioxide?