The evidence also suggests that the toxicity of TiO2 particles may be reduced when eaten as part of the diet. This is because proteins and other molecules in a person's diet can bind to the TiO2 particles. This binding alters the physical and chemical properties of the particles, which influences how they interact with cells, tissues and organs.
Titanium dioxide (E 171) is authorised as a food additive in the EU according to Annex II of Regulation (EC) No 1333/2008.
CSPI says it might reconsider its rating if specifications for food-grade titanium dioxide in the U.S. are updated to ensure nanoparticles are minimized, and new studies are conducted to assess its capacity to cause cancer or other health problems.