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 concern from animal studies is that high amounts of titanium dioxide have increased inflammation and colon tumor formation, said Dr. Johnson-Arbor. A 2021 review, meanwhile, suggested that using titanium dioxide as a food additive weakens the gut lining and worsens the progression of inflammatory bowel disease.

Though the regulated use of titanium dioxide in food products is legal in the U.S. and Canada, it's banned in some other countries, notably throughout Europe. In May 2021, the European Food Safety Authority announced that titanium dioxide can no longer be considered safe as a food additive.