The mineral appears to have low skin penetration, but it is a greater concern when inhaled frequently over time.

Lithopone 30% CAS No. 1345-05-7 / Storage method

In 1970, Japanese scholars studied the phase diagram of iron oxide microcrystalline formation, which laid a theoretical foundation for the preparation method of iron oxide yellow crystal seed. According to the research results, iron yellow crystal seeds can be formed under acidic or alkaline conditions. Because iron yellow is a crystal structure, in order to crystallize into pigment particles, it must first form crystal nucleus and become crystal seed, and then the crystal nucleus grows into iron yellow. Otherwise, only thin and dim color paste can be obtained, which does not have pigment properties. Acid process can be divided into iron sheet process and drop addition process.

In terms of sustainability, the use of rutile titanium dioxide in coatings aligns with the global push towards eco-friendliness. The product is non-toxic and, when combined with solvent-free formulations, can contribute to reduced volatile organic compound (VOC) emissions, making it a safer option for both the environment and those applying the coatings.

if you compare the levels—which went as high as 50,000 milligrams/killigrams per day— to what humans are actually exposed to, we're talking orders of magnitude. It was a huge amount, Norbert Kaminski, PhD, a professor of pharmacology & toxicology and director of the Center for Research on Ingredient Safety at Michigan State University told Health.

To ensure the optimal precipitation percentage, it is important to carefully control these factors during the precipitation process. For example, a higher concentration of titanium sulfate will typically result in a higher precipitation percentage, but may also lead to the formation of impurities. On the other hand, a lower pH of the reaction mixture can promote the precipitation of titanium hydroxide, but may also result in a lower precipitation percentage.

The main concern with nanoparticles is that they are so tiny that they are absorbed into the skin more than we want them (ideally sunscreen should remain on the surface of the skin). Once absorbed they might form unwanted complexes with proteins and they might promote the formation of evil free radicals. But do not panic, these are concerns under investigation. A 2009 review article about the safety of nanoparticles summarizes this, to date, in-vivo and in-vitro studies have not demonstrated percutaneous penetration of nanosized particles in titanium dioxide and zinc oxide sunscreens. The English translation is, so far it looks like sunscreens with nanoparticles do stay on the surface of the skin where they should be.  

Genotoxicity and cytotoxicity 

Because of the uncertainty of the impacts of nanoparticles, Made Safe exercises the precautionary principle, meaning we avoid nanoparticles until more extensive scientific testing proves their safety.