A1:

While loose titanium dioxide presents a problem, titanium dioxide within sunscreen formulations presents a much safer option than conventional sunscreen chemicals like oxybenzone and octinoxate. However, titanium dioxide may become dangerous when it is nanoparticle size. Generally, nanoparticles can be 1000 times smaller than the width of a human hair. Despite nanoparticles becoming increasingly common across industries, they have not been properly assessed for human or environmental health effects, nor are they adequately regulated. Researchers don’t quite understand the impacts nanoparticles could have on human health and the environment. However, because of their infinitesimally small size, nanoparticles may be more chemically reactive and therefore more bioavailable, and may behave differently than larger particles of the same substance; these characteristics may lead to potential damage in the human body or ecosystem.

Titanium dioxide is found in pretty much all makeup & sunscreen.

And studies have long shown that products applied to the skin end up in the bloodstream within half an hour. With penetration rates depending on where they are applied. Absorption rates for your face & scalp are 5-10 times higher than on other parts of our body (Hotchkiss 1994).

Not to mention that in 2005, the Environmental Working Group published a combination of two studies that found toxic chemicals in the umbilical cord blood of newborn babies born in the U.S. They screened for more than 400 chemicals, and an astounding 287 toxins were detected within the umbilical cord blood of these newborns. Of these 287 chemicals, 217 were neurotoxins, and 208 are known to damage growth development or cause birth defects.

Technical Specifications：(Standard：Q/SNBJ1-2012)  

A 2022 review on past studies of titanium dioxide and rat lung cancer, for instance, said the original study was under extreme conditions and its effects were not replicated in other animal species. Additionally, the review concluded that the few studies which did directly focus on titanium dioxide's impact on humans did not end up showing any increased cancer risk.

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.