A study published in the Journal of Agricultural and Food Chemistry in 2019 sought to examine the effects of titanium dioxide on intestinal inflammation. Researchers did this by feeding rats titanium dioxide nanoparticles and found that, after the course of two to three months, the animals had lower body weights and induced intestinal inflammation. The researchers also found the nanoparticles altered gut microbiota composition and aggravated chronic colitis. The rats also experienced reduced populations of CD4+T cells (which are cells that help organize immune responses by prompting other immune cells to fight infection), regulatory T cells, and white blood cells in mesenteric lymph nodes. The researchers wrote: “Dietary TiO2 nanoparticles could interfere with the balance of the immune system and dynamic of gut microbiome, which may result in low-grade intestinal inflammation and aggravated immunological response to external stimulus, thus introducing potential health risk.”

The global Lithopone market size was valued at $169.8 million in 2019, and is projected to reach $218.6 million by 2027, growing at a CAGR of 3.3% from 2020 to 2027.

After conducting a review of all the relevant available scientific evidence, EFSA concluded that a concern for genotoxicity of TiO₂ particles cannot be ruled out. Based on this concern, EFSA’s experts no longer consider titanium dioxide safe when used as a food additive. This means that an Acceptable Daily Intake (ADI ) cannot be established for E171.