Sub-acute oral toxicity study with fullerene C60 in rats.

To obtain initial information on the possible repeated-dose oral toxicity of fullerene C60, Crl:CD(SD) rats were administered fullerene C60 by gavage once daily at 0 (vehicle: corn oil), 1, 10, 100, or 1,000 mg/kg/day for 29 days, followed by a 14-day recovery period. No deaths occurred in any groups, and there were no changes from controls in detailed clinical observations, body weights, and food consumption in any treatment groups. Moreover, no treatment-related histopathological changes were found in any organs examined at the end of the administration period and at the end of the recovery period. Blackish feces and black contents of the stomach and large intestine were observed in males and females at 1,000 mg/kg/day in the treatment group. There were no changes from controls in the liver and spleen weights at the end of the administration period, but those weights in males in the 1,000 mg/kg/day group increased at the end of the recovery period. Using liquid chromatography-tandem mass spectrometry, fullerene C60 were not detected in the liver, spleen or kidney at the end of the administration period and also at the end of the recovery period. In conclusion, the present study revealed no toxicological effects of fullerene C60; however, the slight increases in liver and spleen weights after the 14-day recovery period may be because of the influence of fullerene C60 oral administration. In the future, it will be necessary to conduct a long-term examination because the effects of fullerene C60 cannot be ruled out.