Because of its ability to absorb UV light, it's particularly useful as an ingredient in sunscreens — while its light-scattering properties are great for applications that require white opacity and brightness, such as in paint and paper.

In an early study Jani et al. administred rutile TiO₂ (500 nm) as a 0.1 ml of 2.5 % w/v suspension (12.5 mg/kg BW) to female Sprague Dawley rats, by oral gavage daily for 10 days and detected presence of particles in all the major gut associated lymphoid tissue as well as in distant organs such as the liver, spleen, lung and peritoneal tissue, but not in heart and kidney. The distribution and toxicity of nano- (25 nm, 80 nm) and submicron-sized (155 nm) TiO₂ particles were evaluated in mice administered a large, single, oral dosing (5 g/kg BW) by gavage. In the animals that were sacrificed two weeks later, ICP-MS analysis showed that the particles were retained mainly in liver, spleen, kidney, and lung tissues, indicating that they can be transported to other tissues and organs after uptake by the gastrointestinal tract. Interestingly, although an extremely high dose was administrated, no acute toxicity was observed. In groups exposed to 80 nm and 155 nm particles, histopathological changes were observed in the liver, kidney and in the brain. The biochemical serum parameters also indicated liver, kidney and cardiovascular damage and were higher in mice treated with nano-sized (25 or 80 nm) TiO₂ compared to submicron-sized (155 nm) TiO₂. However, the main weaknesses of this study are the use of extremely high single dose and insufficient characterisation of the particles.

In 2022, a year after the EFSA recommended against the use of E171, the Food Standards Australia New Zealand (FSANZ) conducted its own reassessment of titanium dioxide as a food additive. The agency concluded that titanium dioxide was indeed safe to use as a food additive. The United Kingdom and Canada came to similar conclusions.

③ Paper making industry: Paper making and paper products industry is the third largest application industry of titanium dioxide. Paper using titanium dioxide has good whiteness, high strength, luster, thin and smooth, and is not easy to penetrate when printing. Under the same conditions, the opacity is 10 times higher than that of paper using calcium carbonate and talc powder, and the weight can also be reduced by 15% to 30%. The amount of titanium dioxide in decorative paper accounts for 20%~40% of its raw materials, and the amount of titanium dioxide in other papers is about 1%~5%. Due to the continuous adjustment of the industrial structure of the paper products industry from 2016 to 2018, according to the data of China Paper Association, the output of China's paper products in 2019 was 72.19 million tons, a significant year-on-year increase of 29.4%, and the use of titanium dioxide increased significantly.