Titanium dioxide is one of the many oxides formed naturally in our environment. Manufacturers source this mined mineral from rutile, brookite, and anatase. It is then processed and refined to meet stringent safety guidelines based on the end-use for the mineral. 

In a review published in 2022 in the journal Archives of Toxicology, researchers found that the ingestion of E171 is a “a definite health risk for consumers and their progeny.” After reviewing dozens of in vivo, ex vivo and in vitro studies on the toxicity of E171, the researchers wrote that two facts must be noted: “First, reprotoxicity studies show that animals of both sexes are impacted by the toxicity of these nanoparticles, underlining the importance of conducting in vivo studies using both male and female animals. Second, human exposure begins in utero via maternal-fetal transfer and continues after birth by breastfeeding. Children are then chronically re-exposed due to their food preferences. To be relevant to the human in vivo situation, experimental studies should therefore consider nanoparticle exposure with respect to the age or life period of the studied population.”