Genotoxicity evaluation of fullerene C60 nanoparticles in a comet assay using lung cells of intratracheally instilled rats

The genotoxicity of fullerene C₆₀ nanoparticles was evaluated in vivo with comet assays using the lung cells of rats given C₆₀ nanoparticles. The C₆₀ nanoparticles were intratracheally instilled as a single dose at 0.5 or 2.5 mg/kg or repeated dose at 0.1 or 0.5 mg/kg, once a week for 5 weeks, to male rats. The lungs were obtained 3 or 24 h after a single instillation and 3 h after repeated instillation. Inflammatory responses were observed in the lungs obtained 24 h after a single instillation at 2.5 mg/kg and repeated instillation at 0.5 mg/kg. Histopathological examinations revealed that C₆₀ nanoparticles caused slight changes including hemorrhages in alveoli and the cellular infiltration of macrophages and neutrophils in alveoli. In comet assays using rat lung cells, no increase in % Tail DNA was found in any group given C₆₀ nanoparticles. These findings indicate that C₆₀ nanoparticles had no potential for DNA damage in comet assays using the lungs cells of rats given C₆₀ even at doses causing inflammation.