aluminum window screen frame material

Although barium sulfate is almost completely inert, zinc sulfide degrades upon exposure to UV light, leading to darkening of the pigment. The severity of this UV reaction is dependent on a combination of two factors; how much zinc sulfide makes up the pigments formulation, and its total accumulated UV exposure. Depending on these factors Lithopone B301, Lithopone B311 powder itself may vary in shade over time, ranging from pure white all the way to grey or even black. To suppress this effect, a dopant might be used, like small amount of cobalt salts, which would be added to the formulation. This process creates cobalt-doped zinc sulfide. The cobalt salts help to stabilize zinc sulfide so it will not have as severe a reaction to UV exposure.

Titanium dioxide has similar uses in non-food products. It is used in sunscreen as effective protection against UVA/UVB rays from the sun, which creates a physical barrier between the sun’s rays and the skin. It’s also used to whiten paint, paper, plastic, ink, rubber, and cosmetics.

Nanotoxicology 

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.

Potential hazards of oral exposure to TiO₂ NPs 

Pigment grade titanium dioxide is produced at a much larger particle size than nano grade. It is used as a colourant to whiten and brighten product formulations. Nano grade titanium dioxide is manufactured into very fine (nano) particles and is transparent and colourless. It is commonly used in sunscreens to provide effective protection from potentially harmful UV rays.

Lithopone in fillers, adhesives, joints and sealants

Is titanium dioxide illegal in other countries?

For research published in 2022 study in the journal Food and Chemical Toxicology, scientists examined “the genotoxicity and the intracellular reactive oxygen species induction by physiologically relevant concentrations of three different TiO2 nanomaterials in Caco-2 and HT29-MTX-E12 intestinal cells, while considering the potential influence of the digestion process in the NMs’ physiochemical characteristics.” They found a “DNA-damaging effect dependent on the nanomaterial,” along with the micronucleus assay suggesting “effects on chromosomal integrity, an indicator of cancer risk, in the HT29-MTX-E12 cells, for all the tested TiO2 nanomaterials.” Researchers concluded that the results showcase “evidence of concern” regarding titanium dioxide used as a food additive.