Chapter 5

Hazards of TiO2 and Amorphous SiO2 Nanoparticles

Lucas Reijnders

Abstract

TiO<sub>2</sub> and amorphous SiO<sub>2</sub> nanoparticles have been described as ‘safe’, ‘non-toxic’ and ‘environment friendly’ in scientific literature. However, though toxicity data are far from complete, there is evidence that these nanoparticles are hazardous. TiO<sub>2</sub> nanoparticles have been found hazardous to humans on inhalation, ingestion and dermal exposure. Ecotoxicity at levels of TiO<sub>2</sub> nanoparticles which are expected in the environment has also been found. Amorphous SiO<sub>2</sub> nanoparticles appear to be hazardous to humans on inhalation and ingestion and there is some evidence for ecotoxicity of amorphous SiO<sub>2</sub> nanoparticles. A main, though not the only, mechanism underlying the hazards of SiO<sub>2</sub> and TiO<sub>2</sub> nanoparticles may be the generation of reactive oxygen species. In view of the lack of scientific data pertinent to quantification of hazard and risk, a precautionary approach to production and usage of SiO<sub>2</sub> and TiO<sub>2</sub> nanoparticles has been advocated. Options for hazard reduction, such as coatings for TiO<sub>2</sub> nanoparticles, functionalization for amorphous SiO<sub>2</sub> nanoparticles and binding of nanoparticles to substrates, and risk reduction, including containment and membrane filtration, are discussed.

Total Pages: 85-96 (12)

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