Effect of Zn-DTPA therapy on the maternal transfer of 241Am or 237Pu to young mice.

Newborn mice exposed to 241Am or 237Pu during gestation and whose mothers were given Zn-DTPA at various times before parturition contained less radioactivity than comparable newborn mice given identical 241Am or 237Pu exposure without Zn-DTPA treatment of the mothers. There was no net increase in radionuclide transfer from mothers to unborn young as a result of maternal administration of Zn-DTPA, regardless of the pregnancy stage during which the radioactivity and decorporation treatments were given. Administration of 241Am followed after three days by extended Zn-DTPA therapy resulted in lower fetal content of radioactivity in litters conceived long after or soon after maternal exposure to 241Am. These data indicate that the risk from Am and Pu to unborn young can be reduced by Zn-DTPA treatment of the pregnant mother and of the female who becomes pregnant subsequently. This information may prove to be of significance with the increasing probability of Am or Pu exposure to women in the nuclear industry who could be pregnant at the time or who may conceive a child in the future.

Comparative toxicity of 226Ra, 239Pu, 241Am, 249Cf, and 252Cf in C57BL/Do black and albino mice.

Groups of C57BL/Do (black and albino) mice were injected with graded activities of 226Ra, 239Pu, 241Am, 249Cf, or 252Cf and were followed throughout life. Bone sarcoma was the principal radiation-induced end point, and the risks associated with average skeletal doses of the four transuranium radionuclides, relative to radium, were determined. The relative biological effectiveness (RBE) was calculated for each emitter by dividing its risk coefficient (bone sarcomas per 10(6) mouse-rad) by the risk coefficient for 226Ra. Combined data for males and females in both black and albino mice gave the following values +/- SD for the RBE relative to 226Ra = 1.0: 239Pu = 15.3 +/- 3.9, 241Am = 4.9 +/- 1.4, 249Cf = 5.0 +/- 1.4, and 252Cf = 2.6 +/- 0.8. About 70% of the tumors occurred in the axial skeleton, and the risk coefficient for females averaged about four times higher than for males when all five nuclides were included. The RBE of fission fragment irradiation from 252Cf for cancer induction, relative to alpha irradiation, for the combined data in all of the animals given 252Cf and 249Cf, was 0.02 +/- 0.28, in agreement with the calculated theoretical value of 0.03, based on the ratio of summed track lengths in tissue.