The honest picture is uncertainty, not proven harm. EFSA (2021) flagged that TiO2 includes a fraction of nanoparticles, that a small amount is absorbed and can accumulate in the body, and that a concern for genotoxicity (DNA/chromosomal damage) could not be ruled out — so no safe intake could be established, triggering the EU ban. The supporting evidence is mechanistic and animal: food-grade TiO2 promoted low-grade colon inflammation and preneoplastic aberrant crypt foci in rats (Bettini 2017), and human-volunteer work confirmed TiO2 particles are absorbed into the bloodstream after oral dosing (Pele 2015). IARC classifies TiO2 as Group 2B "possibly carcinogenic to humans" — but that is based on lung tumors in rats from inhaling dust (an occupational/respiratory route), NOT from eating it, so it does not directly speak to dietary risk. Crucially, there are no human studies linking dietary E171 to cancer or disease, and FDA, JECFA, Health Canada and the UK FSA reviewed the same data and judged the genotoxicity tests not representative of the food-grade material or relevant exposure route. Bottom line: not a demonstrated hazard at dietary levels, but enough unresolved nanoparticle/genotoxicity uncertainty that the EU applied the precautionary principle. People who prefer to avoid it can check labels for "titanium dioxide"/E171, including on supplements and medications; there is no established at-risk subgroup. Educational only — always check with your doctor or pharmacist before combining Titanium Dioxide with any medicine.