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.”

TiO₂ has been well accepted in the food industry and can be found as the E171 additive in various food products, mainly for whitening and texture. It is present in some cottage and Mozzarella cheeses, horseradish cream and sauces, lemon curd, and in low-fat products such as skimmed milk and ice-cream. Even if the product is labelled as containing E171, no information is usually given about the quantity, particle size and particle structure. FDA claims that TiO₂ may be safely used as a colour additive for colouring foods in quantities up to 1 % by weight of the food. Interestingly, TiO₂ is frequently declared as a “natural colouring agent” and is therefore well accepted by consumers.

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.