Nanotitanium dioxide toxicity in mouse lung is reduced in sanding dust from paint

Background: Little is known of how the toxicity of nanoparticles is affected by the incorporation in complex matrices. We compared the toxic effects of the titanium dioxide nanoparticle UV-Titan L181 (NanoTiO(2)), pure or embedded in a paint matrix. We also compared the effects of the same paint with and without NanoTiO(2). Methods: Mice received a single intratracheal instillation of 18, 54 and 162 mu g of NanoTiO(2) or 54, 162 and 486 mu g of the sanding dust from paint with and without NanoTiO(2). DNA damage in broncheoalveolar lavage cells and liver, lung inflammation and liver histology were evaluated 1, 3 and 28 days after intratracheal instillation. Printex 90 was included as positive control. Results: There was no additive effect of adding NanoTiO(2) to paints: Therefore the toxicity of NanoTiO(2) was reduced by inclusion into a paint matrix. NanoTiO(2) induced inflammation in mice with severity similar to Printex 90. The inflammatory response of NanoTiO(2) and Printex 90 correlated with the instilled surface area. None of the materials, except of Printex 90, induced DNA damage in lung lining fluid cells. The highest dose of NanoTiO(2) caused DNA damage in hepatic tissue 1 day after intratracheal instillation. Exposure of mice to the dust from paints with and without TiO2 was not associated with hepatic histopathological changes. Exposure to NanoTiO(2) or to Printex 90 caused slight histopathological changes in the liver in some of the mice at different time points. Conclusions: Pulmonary inflammation and DNA damage and hepatic histopathology were not changed in mice instilled with sanding dust from NanoTiO(2) paint compared to paint without NanoTiO(2). However, pure NanoTiO(2) caused greater inflammation than NanoTiO(2) embedded in the paint matrix.