[Biological radiation effects of carbon-14- and tritium-labeled 5-fluorouracil].

This paper describes the biological radiation effects of carbon-14 and tritium labeled 5-fluorouracils (5-FU) which were given intraperitoneally at reasonable dose (14C: 1.85 MBq/kg (0.05 microCi/kg), 3H: 3.7 MBq/kg (0.1 microCi/kg)) and its forty times dose once a day for 3 days in mice. The results indicated that the change of body weight, urine and feces volume and its radioactivity, and organ weight and its residual radioactivity except pancreas were not observed any significant difference between three groups of both 14C and 3H, but white blood cell number markedly decreased proportionally with radioisotope dose of both 14C and 3H and also red blood cell number decreased by [6-3H]-5-FU 148 MBq/kg i.p. The results suggest that high level radioisotope dose of both 14C and 3H 5-FUs have no biological radiation effects on the studies of drug metabolism in vivo, however that in the case of hematogenic organ, the biological radiation effect is not disregarded.