Because of its unique pigment and fine-milled texture, titanium dioxide has become popular over the past century in a wide variety of different products. These include adhesives, paints, plastics, rubbers, textiles, inks, ceramics, and even some pharmaceuticals, foods, and hygiene products.

The price of Titanium Dioxide in Taiwan rose considerably throughout December 2018, reaching 3,750 USD per metric ton.  The price in Taiwan is 10% higher than the average price in the previous month and 1% higher than the average price one year before. In contrast, Titanium Dioxide prices in India were flat during December 2018, and were decline when compared to the average price in the preceding yeara decline of 3% from the previous year’s price. 

In order to contribute with experimental evidence that could help to achieve a better understanding of the field for future regulation, in the present work, the biocompatibility of commercial P25TiO₂NPs (one type of TiO₂NPs used in sunscreen formulations) and two novel functionalized P25TiO₂NPs were evaluated under solar simulated irradiation. White light, generated by red, blue, and yellow LEDs, together with UV ones, was chosen to simulate the solar spectra. Functionalization of TiO₂NPs was made with antioxidant vitamins in order to prevent the expected photo-initiated ROS production when nanoparticles are exposed to the simulated solar spectra. Vitamin B2 (riboflavin) and vitamin C were chosen to carry out the functionalization because they are water-soluble, low-cost, and are a constitutive part of biological processes. In addition, it is known that both have the potential to prevent macromolecular oxidation by ROS [23], [24], [25], [26].

It should also be considered that due to the low pH in the stomach, the increased dissolution of the TiO₂ particles may increase its bioavailability and may facilitate the entry of titanium ions into the blood circulation. Despite the relatively large consumption of TiO₂ as a food additive, no studies on the effect of pH on its absorption and bioavailability have been found in the literature. This can be attributed to a general belief that TiO₂is completely insoluble. However, this is not completely true, as TiO₂ particles show a certain degree of solubility.