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Our scientific experts applied for the first time the 2018 EFSA Scientific Committee Guidance on Nanotechnology to the safety assessment of food additives. Titanium dioxide E 171 contains at most 50% of particles in the nano range (i.e. less than 100 nanometres) to which consumers may be exposed.  

As early as sixty years ago, zinc sulphide was first thought of as a pigment for coloring India rubber and a patent for the process of its manufacture was issued in England. But it was not until twenty years later that zinc sulphide and its manufacture was seriously considered as a pigment for paint, and in 1874 a patent was issued for a process of manufacturing a white pigment, composed of zinc sulphide and barium sulphate, known as Charlton white, also as Orr's white enamel. This was followed in 1876 by a patent issued to a manufacturer named Griffith and the product, which was similar in character to Charlton white, was known as Griffith's patent zinc white. In 1879 another patent for a more novel process was obtained by Griffith & Cawley, the product made under this process proving the best of the series placed upon the market up to that date. After that time many new processes were patented, all, however, tending to the same object, that of producing a white pigment, composed of zinc sulphide and barium carbonate, the results, however, in many cases ending with failure.

How pure TiO2 is extracted from titanium-containing molecules depends on the composition of the original mineral ores or feedstock. Two methods are used to manufacture pure TiO₂: a sulphate process and a chloride process.

Is titanium dioxide safe?

What is the FDA limit for titanium dioxide?

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.  

Resumo–Este artigo discute a descoberta de litopônio fosforescente em desenhos de aquarela do artista americano John La Farge datados de entre 1890 e 1905 e a história do litopônio na indústria de pigmento no final do século XIX e início do século XX. Apesar de ter muitas qualidades desejáveis para o uso em aquarela branca ou tintas a óleo, o desenvolvimento do litopônio como um pigmento de artistas foi prejudicado por sua tendência a se escurecer na luz solar. Sua disponibilidade para e uso por parte de artistas ainda não está clara, uma vez que os catálogos comerciais dos vendedores de tintas geralmente não eram explícitos na descrição de pigmentos brancos como algo que contém litopônio. Além disso, o litopônio pode ser confundido com o branco de chumbo durante o exame visual e sua fosforescência de curta duração pode ser facilmente perdida pelo observador desinformado. O litopônio fosforescente foi documentado em apenas um outro trabalho até hoje: uma aquarela de Van Gogh. Além da história da manufatura do litopônio, o artigo detalha o mecanismo para a sua fosforescência e sua identificação auxiliada pela espectroscopia de Raman e espectrofluorimetria.

It is suitable as an alternative to titanium dioxide when higher acid resistance is required, such as in adhesive joints and sealants. 

A few non-dietary studies have reported adverse effects in the gastrointestinal tract of laboratory animals given food-grade TiO₂. However, these same effects were not seen when the same or higher doses of food-grade TiO₂ were administered in the animals' diet. Dietary studies best reflect how humans are exposed to TiO₂ from food. Thus, the Food Directorate placed the most emphasis on the results of these studies in the state of the science report.