TiO₂ comes in many different forms. However, only a few of these forms are considered food-grade (acceptable to be added to food). Many studies that raised concern about the safety of TiO₂, including the concern for genotoxicity, used forms of TiO₂ that are not considered acceptable for use in food and have different properties than food-grade TiO₂. Other studies did use food-grade TiO₂, but took steps to break the material down into smaller particles than what would normally be found in food.

The FDA is reviewing the safety of titanium dioxide in response to an April petition from EWG and other environmental and public health groups. This is the FDA’s first comprehensive review of titanium dioxide since 1973.

The ROS seemed to be endlessly produced by P25TiO₂NPs upon irradiation, since the values detected after 6 h are similar to the ones after 3 h. However, the amount of vitamin B2 in the surface of the NPs proved to be enough to decrease the ROS detected even after 6 h. Statistical analysis showed a significant difference between C and A. p < 0.05