Nanotoxicology “focuses on determining the adverse effects of nanomaterials on human health and the environment.”

This study & others have lead France to ban Titanium Dioxide as a Food Additive.

Research supports that applying titanium dioxide to the skin in the form of sunscreens, makeup, and other topical products does not pose any health risks. 

Above 10%, 1 kg of TiO2 should be replaced by 1.3 kg of Lithopone 30%, reducing the amount of polymer accordingly. 

Food additive or carcinogen? The growing list of chemicals banned in EU but used in US, by Mikaela Conley, The Guardian, June 23, 2022

Just because we are applying makeup containing titanium dioxide as one of the ingredients does not equate sufficient coverage. Instead of relying on mineral makeup, try layering it over your daily sunscreen instead.

As mentioned above, these oxide NPs are harmful in part because both anatase and rutile forms are semiconductors and produce ROS. Particularly, P25 kind has band-gap energies estimated of 3.2 and 3.0 eV, equivalent to radiation wavelengths of approximately 388 and 414 nm, respectively. Irradiation at these wavelengths or below produces a separation of charge, resulting in a hole in the valence band and a free electron in the conduction band, due to the electron movement from the valence to conduction bands. These hole–electron pairs generate ROS when they interact with H₂O or O₂ [43,44]. It was described that they can cause an increase in ROS levels after exposure to UV-visible light [45]. The NBT assay in the studied samples showed that bare P25TiO₂NPs produce a large amount of ROS, which is drastically reduced by functionalization with vitamin B2 (Fig. 5). This vitamin, also known as riboflavin, was discovered in 1872 as a yellow fluorescent pigment, [46] but its function as an essential vitamin for humans was established more than sixty years later, and its antioxidant capacity was not studied until the end of the XX century [47,48]. This antioxidant role in cells is partially explained because the glutathione reductase enzyme (GR) requires it for good functionality. This enzyme is the one in charge of the conversion of oxidized glutathione to its reduced form which acts as a powerful inner antioxidant and can quench the ROS [49,50]. The cost of this action is that the glutathione is converted to the oxidized form and needs to be recovered by the GR. Consequently, the cells need more vitamin B2. Another glutathione action is the protection against hydroperoxide. This activity is also mediated by riboflavin. Therefore, local delivery of this vitamin seems to significantly help the cells in their fight to keep the oxidative balance, once they are exposed to high levels of ROS.