To be added to food, this additive must achieve 99% purity. However, this leaves room for small amounts of potential contaminants like lead, arsenic, or mercury (1Trusted Source).
Most food-grade titanium dioxide is around 200–300 nanometers (nm) in diameter. This size allows for ideal light scattering, resulting in the best color (1Trusted Source).
Finally, research has shown that titanium dioxide nanoparticles do not pass the first layer of the skin — the stratum corneum — and are not carcinogenic (7Trusted Source, 15Trusted Source).
Other experts say there is simply no conclusive evidence at this point that titanium dioxide is damaging to humans after ingesting. Kaminski in particular said the research studies cite health hazards that were found by using high doses of the product, which you would not normally see in food.