Scientists analyzed research that examined how titanium dioxide nanoparticles interact with the brain for a 2015 review published in Nanoscale Research Letters. The researchers wrote: “Once the TiO2 NPs are translocated into the central nervous system through [certain] pathways, they may accumulate in the brain regions. For their slow elimination rates, those NPs could remain in the brain zones for a long period, and the Ti contents would gradually increase with repeated exposure.” After reviewing dozens of studies, the scientists concluded: “Long-term or chronic exposure to TiO2 nanoparticles could potentially lead to the gradually increased Ti contents in the brain, which may eventually induce impairments on the neurons and glial cells and lead to CNS dysfunction as a consequence.”

Of the products that include the additive in their labels, Thea Bourianne, senior manager at data consultant Label Insights, told Food Navigator USA in May 2021 that more than 11,000 products in the company's database of U.S. food and beverage products listed titanium dioxide as an ingredient. Non-chocolate candy led those numbers at 32%. Cupcakes and snack cakes made up 14%, followed by cookies at 8%, coated pretzels and trail mix at 7%, baking decorations at 6%, gum and mints at 4% and ice cream at 2%.