In 2021, the European Food Safety Authority concluded that titanium dioxide is no longer safe in foods due to the same concerns over nanoparticles. As a result, titanium dioxide is now banned as a food additive in the EU. Although studies have shown that the absorption of ingested titanium dioxide is low, evidence suggests that titanium dioxide nanoparticles can accumulate in the body over time. Health Canada deemed it safe in 2022 but noted concerns. Unlike their European counterparts, Canadian officials did not consider studies performed with titanium dioxide nanoparticles alone. 

In a study published in the journal Environmental Toxicology and Pharmacology in 2020, researchers examined the effects of food additives titanium dioxide and silica on the intestinal tract by grouping and feeding mice three different food-grade particles — micro-TiO2, nano-TiO2, and nano-SiO2.  With all three groups, researchers observed changes in the gut microbiota, particularly mucus-associated bacteria. Furthermore, all three groups experienced inflammatory damage to the intestine, but the nano-TiO2 displayed the most pronounced changes. The researchers wrote: “Our results suggest that the toxic effects on the intestine were due to reduced intestinal mucus barrier function and an increase in metabolite lipopolysaccharides which activated the expression of inflammatory factors downstream. In mice exposed to nano-TiO2, the intestinal PKC/TLR4/NF-κB signaling pathway was activated. These findings will raise awareness of toxicities associated with the use of food-grade TiO2 and SiO2.”