Lithopone, white powder, relative density: 4.136 ~ 4.39 g / mL, insoluble in water. It is a mixture of zinc sulfide and barium sulfate. Inorganic white pigment, widely used in plastics such as polyolefin, vinyl resin, ABS resin, polystyrene, polycarbonate, nylon and polyoxymethylene, and white pigments of paints and inks. It is less effective in polyurethane and amino resins and less suitable in fluoroplastics. It is also used for coloring of rubber products, paper, varnish, tarpaulin, leather, watercolor paint, paper, enamel, and the like. Used as a binder in the production of electric beads.

On the other hand, the U.S. Food and Drug Administration (FDA) in their Final Administrative Order on Sunscreen Drug Products posted in September 2021 still accepts titanium dioxide up to 25% in the list of Generally Recognized As Safe and Effective (GRASE) in the main document, without further clarification on what kind or size of particles [9]. However, on page 24 (Sunscreen containing nanomaterials) FDA clearly “distinguish nanomaterials from other forms of these ingredients'' (zinc oxide and titanium dioxide) and ask for comments on “any particular nanomaterials that you believe should not be permitted for use in OTC sunscreen products”. To the best of our knowledge, this Agency did not ban the use of nanoparticulate titanium dioxide in any form, even though it is mentioned on page 34 that the anatase form is the more photoactive one, due to the lack of evidence with real sunscreens OTC (over the counter) in vivo. Moreover, other regulations in Latin America (MERCOSUR agreement, 2006) do not state clearly their position on the use of nanoparticulate TiO₂NPs [10].