In a study by Coccini et al, published in the journal Neurotoxicology, titanium dioxide nanoparticles were reported to enter the brain, where they can cause neurotoxic effects.

Titanium dioxide (TiO2) is used in a variety of personal care products, including sunscreens, pressed powders, and loose powders, as a UV filter or whitening agent. In lotions and creams, it presents low risk of exposure. However, when TiO2 is inhalable—as it may be in powders—it is considered a possible carcinogen by the International Agency for Research on Cancer.

Learn more about titanium dioxide here.