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Titanium dioxide (TiO2) is used in a variety of personal care products, including sunscreens, pressed powders, and loose powders, as a UV filter or whitening agent. In lotions and creams (dermal exposure), it is not a risk for adverse health effects. However, when titanium dioxide is inhalable—as it may be when in powder form—it is considered a possible carcinogen by the International Agency for Research on Cancer.Titanium dioxide nanoparticles do not appear to confer any unique health hazards.

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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.”

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