There seems to be some disagreement, but TiO2 (a very white pigment powder) is generally considered safe and has been used in everything from wall paint to toothpaste for decades. A few studies have suggested possible genetic toxicity, but it may be only from the extremely small nano-particle form. Another study suggested lung problems much like asbestos, but that might be from breathing high level aerosol concentrations. All in all, there’s no clear consensus, which seems like a pretty good sign for such a commonly used material, but the jury is still out.