Nano-sized P25TiO₂NPs were kindly donated by Dr. Scaiano, Ottawa University (Canada). Riboflavin (vitamin B2) was from Sigma and ascorbic acid (vitamin C) and KBr (for IR pills) were from Cicarelli. Base cream for the animal experiments was purchased from Todo Droga and the LED panel was built ad hoc.

But what is titanium dioxide, exactly? Here's what you need to know about this popular food additive — including what products it's used in and whether it's safe to consume.

1. 296 to 1.357 g/cm3 is obtained. The reaction solution is subjected to pressure filtration through a plate frame to obtain a cake-like lithopone powder having a water content of not more than 45%. The mixture is calcined in a dry roaster to change the crystal form of the lithopone, and then acid-washed with sulfuric acid at a temperature of 80 °C. Finally, it is washed with water, reinforced with coloring agent, pressure filtration, drying and milling.

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