According to the American Chemistry Council, titanium dioxide (TiO2) is an inorganic substance that's used as a white powder in a variety of industrial and consumer goods, including in sunscreen, cosmetics, toothpaste, paint, plastics, food and more.

After oral ingestion, the absorption of titanium dioxide particles is low, however they can accumulate in the body, Maged Younes, chair of the European Food Safety Authority's expert Panel on Food Additives and Flavourings, said in a May 2021 statement.

The CaCO3 and TiO2 factory plays a crucial role in producing these materials on a large scale to meet the growing demand from various industries. The factory utilizes advanced technology and processes to extract and refine CaCO3 and TiO2 from natural resources such as limestone and mineral sands. The production process involves crushing, grinding, and chemical treatment to obtain the desired properties of CaCO3 and TiO2.

In a 2019 study published in the journal Nanotoxicology, researchers recreated the first phase of digestion in mice and fed them titanium dioxide, then examined whether accumulation occurred in the organs. Researchers wrote: “Significant accumulation of titanium was observed in the liver and intestine of E171-fed mice; in the latter a threefold increase in the number of TiO2 particles was also measured. Titanium accumulation in the liver was associated with necroinflammatory foci containing tissue monocytes/macrophages. Three days after the last dose, increased superoxide production and inflammation were observed in the stomach and intestine. Overall, [this] indicates that the risk for human health associated with dietary exposure to E171 needs to be carefully considered.”

After oral ingestion, the absorption of titanium dioxide particles is low, however they can accumulate in the body, Maged Younes, chair of the European Food Safety Authority's expert Panel on Food Additives and Flavourings, said in a May 2021 statement.

A few non-dietary studies have reported adverse effects in the gastrointestinal tract of laboratory animals given food-grade TiO₂. However, these same effects were not seen when the same or higher doses of food-grade TiO₂ were administered in the animals' diet. Dietary studies best reflect how humans are exposed to TiO₂ from food. Thus, the Food Directorate placed the most emphasis on the results of these studies in the state of the science report.

When E171 isn’t combined with other ingredients and administered in water, some studies suggest that under these artificial conditions, E171 may be processed differently in the body resulting in some biological changes in experimental animals that are poorly understood.