Distribution and biomarkers of carbon‐14‐labeled fullerene C 60 ([ 14 C(U)]C 60 ) in female rats and mice for up to 30 days after intravenous exposure

A comprehensive distribution study was conducted in female rats and mice exposed to a suspension of uniformly carbon‐14‐labeled C 60 ([ 14 C(U)]C 60 ). Rodents were administered [ 14 C(U)]C 60 (~0.9 mg kg −1 body weight) or 5% polyvinylpyrrolidone‐saline vehicle alone via a single tail vein injection. Tissues were collected at 1 h and 1, 7, 14 and 30 days after administration. A separate group of rodents received five daily injections of suspensions of either [ 14 C(U)]C 60 or vehicle with tissue collection 14 days post exposure. Radioactivity was detected in over 20 tissues at all time points. The highest concentration of radioactivity in rodents at each time point was in liver, lungs and spleen. Elimination of [ 14 C(U)]C 60 was < 2% in urine and feces at any 24 h time points. [ 14 C(U)]C 60 and [ 14 C(U)]C 60 ‐retinol were detected in liver of rats and together accounted for ~99% and ~56% of the total recovered at 1 and 30 days postexposure, respectively. The blood radioactivity at 1 h after [ 14 C(U)]C 60 exposure was fourfold higher in rats than in mice; blood radioactivity was still in circulation at 30 days post [ 14 C(U)]C 60 exposure in both species (