Effect of age on Zn-DTPA removal of Am and Pu

Decorporation in beagles of monomeric Am-241 and Pu-237+239, given i.v., by 30 μmol Zn-DTPA/kg injected once each day from 14 to 154 days after radionuclide administration was more effective in juvenile animals aged 3 months than in young adults aged 1.9 years and was least effective in mature dogs aged 10 years. Retention of Am in liver diminished during DTPA therapy from a pretreatment value of 48% to 10% in the mature adults and from 55% to less than 1% in the young adults, while the corresponding liver retention of juveniles decreased from 17% to undetectable levels by 28 days of treatment. Pu retention in liver diminished during therapy from adult pretreatment levels of 31% and 33% to 10% and 6% in the mature and young adults, respectively, while juvenile liver retention decreased from pretreatment levels of 14% to undetectable by 56 days of therapy. Non-liver Am (mainly skeleton) diminished during treatment in mature adults from 43% to 25%, in young adults from 35% to 20% and in juveniles from 72% to 9%. Non-liver Pu decreased from 53% to 33% for mature adults, from 51% to 30% in young adults and from 76% to 17% for juveniles during the 140 days of daily Zn-DTPA therapy