For a mini-review published in the journal Particle and Fibre Technology in 2021, scientists wanted to evaluate whether Ti02 particles contributed to the development and/or exacerbation of irritable bowel disease, and whether they altered the four elements of intestinal barrier function: the intestinal microbiota, the immune system, the mucus layer, and the epithelium. The breakdown of these four elements can contribute to autoimmune, neurological, inflammatory, infectious, and metabolic diseases. Following their review, the researchers concluded: “Data indicate that TiO2 is able to alter the four compartments of IBF and to induce a low-grade intestinal inflammation associated or not with pre-neoplastic lesions.” 

Having thus described the origin and uses of the pigment, we now come to the question, what is lithopone? It is, in short, a chemical compound usually consisting of 30.5 per cent zinc sulphide, 1.5 per cent zinc oxide and 68 per cent barium sulphate, but these proportions vary slightly in the different makes. Lithopone of this composition is sold as the highest grade, either as red seal or green seal, as it best suits the idea of the manufacturer. Many manufacturers, especially in Europe, sell and also export other brands under other seals, containing 24, 20, 18 and as little as 12 per cent of zinc sulphide with very small percentages of zinc oxide, the balance being usually barium sulphate, but sometimes certain portions of China clay or gypsum (calcium sulphate) or whiting (calcium carbonate). Such brands are not a chemical compound, but mechanical mixtures of the chemically compounded lithopone and the admixtures referred to.

The EU expert panel did not identify an immediate health concern linked to TiO₂ when used as a food additive. However, due mainly to uncertainties concerning the safety of TiO₂ nanoparticles, the panel concluded that TiO₂ as a food additive (E171) could no longer be considered safe.

Animal studies show exposure to titanium dioxide is linked to immunotoxicity, inflammation and neurotoxicity. 

Amount: if too little titanium dioxide is added, the distance between particles is too large and there is not enough opacity, while if the titanium content is too high, the particles interfere with each other and poor efficiency is obtained.

≥ 5 % of standard sample

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.”