Lithopone has therefore traditionally been used in stoppers and putties, jointing compounds and sealing compounds, primers and undercoats and in road-marking paints.

In 2017, French researchers from the Institut National de la Recherche Agronomique (INRAE) were among the first to examine the effects of E171 nanoparticles on the body. They fed rats a dose of 10mg of E171 per kilogram of body weight per day, which was similar to human exposure in food. The research, which was published in Scientific Reports, showed that E171 was able to traverse the intestinal barrier, pass into the bloodstream, and reach other areas of the body in rats. Researchers also found a link between immune system disorders and the absorption of titanium dioxide nanoparticles. 

There’s also concern that exposure to the mineral over time, even in small amounts, can build up in the body, particularly in the kidneys, spleen and liver. Although most of the mineral is excreted in feces, there is evidence that a small percentage may remain in bodily organs.