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.

All samples (n = 6) were irradiated in a 96 well plate using an LED panel on top for 3 and 6 h before analysis. An identical set of samples were kept in the dark as controls. The temperature was checked and did not go over 37 °C. The intensity of light was also measured and was constant at 19,500.10 lux. (43.33 W in 0.2 m²), about 5 times less than actual solar light intensity on Earth's surface Therefore, these findings are indicative of even greater danger in real life.

Why does the exposure route matter, and what's the risk? 

A number of our toothpastes do not contain titanium dioxide, including some of our Signal products (Signal Bio, Signal Nature Element, Signal White System, Signal Kids (Baby & Junior), Signal White Now Detox, Signal Anti-Cavity), Love Beauty and Planet and Schmidt’s Naturals.