A safety review conducted by the EFSA in 2021 assessed thousands of studies published on titanium dioxide.

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 production of ROS was studied on white blood cells as a model to screen the effect on eukaryotic cells after being exposed to samples and solar simulated irradiation (according to the level of penetration under the skin). For that purpose, the leukocytes were separated from anticoagulated fresh blood using the Ficoll-Hypaque reactive in a well-known technique [33]. Then, 50 μL of suspensions of P25TiO₂NPs (0.2 mg/mL and 0.02 mg/mL), vitaminB2@P25TiO₂NPs (0.2 mg/mL and 0.02 mg/mL) and vitamin B2 (0.2 mg/mL and 0.02 mg/mL) were prepared and mixed with 50 μL of white blood cells suspension. A solution of 3% H₂O₂ was used as positive control and PBS as negative control. Then, the samples were irradiated using the LED panel for 3 and 6 h to simulate the light penetration into the skin. Also, a set of samples was kept in the dark as control. Finally, the ROS were detected through the colorimetric assay employing the nitroblue tetrazolium salt (NBT salt) and the absorbance at 650 nm was measured. The experiment was reproduced twice; the standard deviation was calculated and p-value < 0.05 were considered significant.

Food containing titanium dioxide that is lawfully placed on the EU market before 7 August 2022 may remain on the market until its date of minimum durability or its ‘use-by’ date has passed. Food produced or placed on the market after 7 August 2022 cannot contain titanium dioxide. The ban on the use of titanium dioxide is effective in each EU Member State, and in Northern Ireland. Some third countries, such as the United Kingdom (excluding Northern Ireland), continue to permit the use of titanium dioxide.

One of the most common worries about titanium dioxide is that it could be a cancer-causing agent. The link between cancer and titanium dioxide traces back to a 1985 study where rats were exposed to high levels of titanium dioxide for two years, causing lung cancer. However, not all experts are convinced by this study.