Titanium dioxide (TiO2) is manufactured worldwide in large quantities for applications ranging from pigments and food additives to photocatalysis. Fine and nanosized TiO2 powders have been extensively studied because of their good photocatalytic properties (P25 TiO2) and for applications including oxidation of organic compounds and the production of H2 as a fuel using solar energy. The TiO2 nanosized particles possess different physicochemical properties in comparison to their fine particle analogs, which influence an alteration in their bioavailability and bioactivity. Consequently, P25 TiO2 nanoparticles for water purification could result in an increased risk for workers and water consumers when being exposed to this engineered nanomaterial (ENM). Yet, little is known about the size distribution of the P25 TiO2 and the impact on health that could arise after ingestion. We studied three TiO2 powders from different suppliers, in which one was food-grade according to the provider. An analysis of several parameters that are reported to influence the toxicity of ENMs (elemental composition, size distribution, and crystal structure) was conducted for the TiO2 samples by Transmission Electron Microscopy (TEM), Energy Dispersive X-Ray Spectroscopy (EDS), and X-Ray Diffraction (XRD). The photocatalytic activity and the percentage of presence of primary nanoscale particles were determined in all the TiO2 samples. All were found to contain TiO2 nanoparticles. The results of a preliminary acute toxicity assessment by the use of Gram-negative bacteria as an ENM toxicity model organism are presented. This study brings us closer, not only to establishing justifiable procedures for the risk management for workers and consumers, but also to foreseeing possible environmental implications of other water treatment techniques when implementing this photocatalytic ENM.

How hazardous can nanostructured titanium dioxide be to humans in a water purification application?

249th National Meeting (2015)

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