Investigation on the genotoxicity of different sizes of gold nanoparticles administered to the lungs of rats.

Nanomaterials are already used today and offer even greater use and benefits in the future. The progress of nanotechnology must be accompanied by investigations of their potential harmful effects. For airborne nanomaterials, lung toxicity is a major concern and obviously the particle size is discussed as a critical property directing adverse effects. While standard toxicological test methods are generally capable of detecting the toxic effects, the choice of relevant methods for nanomaterials is still discussed. We have investigated two genotoxic endpoints - alkaline Comet assay in lung tissue and micronucleation in polychromatic erythrocytes of the bone marrow - in a combined study 72 h after a single instillation of 18 μg gold nanoparticles (NP) into the trachea of male adult Wistar rats. The administration of three test materials differing only in their primary particle size (2, 20 and 200 nm) did not lead to relevant DNA damage in the mentioned tests. The measurement of clinical pathology parameters in bronchoalveolar lavage fluid (BALF) and blood indicated neither relevant local reactions in the animals' lungs nor adverse systemic effects. Minor histopathology findings occurred in the lung of the animals exposed to 20 nm and 200 nm sized nanomaterials. In conclusion, under the conditions of this study the different sized gold NP tested were non-genotoxic and showed no systemic and local adverse effects at the given dose.