Titanium dioxide

Titanium dioxide is a white to almost white powder which is practically insoluble in water, dilute acids and alkalis; slowly soluble in sulphuric acid and molten sodium hydrogen sulphate.

The classification as "bio-inert" material has led to a wide spread use of normal sized (>100 nm) titanium dioxide (food, pharmaceutical and cosmetic products).

In the case of pharmaceuticals and food supplements, titanium dioxide is usually indicated specifically as "titanium dioxide". In food, titanium dioxide is declared under E 171, in cosmetics with the abbreviation CI 77891 and in the color range with PW6 for Pigment White 6.

Titanium dioxide is mainly used as a highly opaque white color pigment (food, cosmetics, painting, paper industry).

Titanium dioxide is widely used as a physical light protection agent.

Due to the wide use of titanium dixoid, its pathogenetic role in potential systemic uptake must be carefully considered. Systemic uptake can be by ingestion, dermal penetration (not secured - Sadrieh N et al. 2010) or inhalation.

Titanium dioxide and silver nanoparticles are rapidly internalized by the immune system and accumulate in peripheral lymphoid organs, but also hepatic (Lappas CM 2015). They induce in loco reactive oxygen species(ROS), inflammation, genotoxicity and possibly carcinogenesis. The extent and type of cell damage depends on the chemical and physical properties of the TiO2 particles.

Penetration through the skin is difficult to prove. With local application of titanium dioxide, after 24-hour exposure, the str. corneum, the epidermis and the dermis can be detected. In the dermis, particles were detected in the upper dermis and around the follicles. The absorbed amount is small and amounts to 0.00014% of the applied amount (cited in Black T 2018).

1. Crosera M et al (2015) Titanium Dioxide Nanoparticle Penetration into the Skin and Effects on HaCaT Cells. Int J Environ Res Public Health 12:9282-9297.

2. Grande F et al (2016) Titanium Dioxide Nanoparticles: a Risk for Human Health? Mini Rev Med Chem 16:762-769.

3. Guglielmotti MB et al (2015) Migration of titanium dioxide microparticles and nanoparticles through the body deposition in the gingiva: an experimental study in rats. Eur J Oral Sci 123:242-248.

4. Lappas CM (2015) The immunomodulatory effects of titanium dioxide and silver nanoparticles. Food Chem Toxicol 85:78-83.

5. Sadrieh N et al (2010) Lack of significant dermal penetration of titanium dioxide from sunscreenformulations
   containing nano- and submicron-size TiO2 particles.Toxicol Sci 115:156-66.

6. Black T (2018) Latest findings on photoprotectors. Close to the skin 34: 6-11

7. Shukla RK et al (2014) Titanium dioxide nanoparticle-induced oxidative stress triggers DNA damage and hepatic injury inmice. Nanomedicine (London) 9:1423-1434.

8. Zhang X et al (2015) Toxicology of nanosized titanium dioxide: an update. Toxicol 89:2207-2217.