The Effect of Mass on Promethium Retention and Removal from the Rat

Abstract

Seven days after intravenous administration to rats of 3.32 x 104-5.36 x lo3 mmol of isotopic-or carricr-diluted PmCl,, the fraction of injected, monomeric promethiurn retained in the skelton was greatest at the lowest mass administered. Generally no m a s effect was observed in kidney, liver or spleen at the monomeric m a s levels administered.The effectiveness of 0.3 mmole diethylenetriaminepentaacetic acid (DTPA) in decreasing the fraction of injected promethium retained in the skeleton following prompt (1 hr) or delayed (48 hr) treatment was less for the lowest mass injected than for other monomeric masses. In the soft tissues, a relatively constant fraction of the control rats' promethium tissue burden was removed by DTPA treatment at all monomeric mass levels. At the highest mass level, particulate formation typically altered the distribution as well as effectiveness of DTPA treatments. While the amount of promethium removed from most of the examined tissues by DTPA treatments at each monomeric level, was an almost constant fraction of that retained in the control tissues, the moles of promethium being removed increased with injected mass as the molar ratio of DTPA:Pm varied from loQ to lo5.In extending the results of animal experiments and tracer-level human experimcnts as predictors of radionuclide retention and of the efficacy of removal procedures in accidental human exposurc situations, due regard should be given to the possible effect of mass as well as to the physical state of the incorporated radionuclide.

Metabolic data for promethium

“…In this report oxides, hydroxides, carbides and fluorides of promethium are assigned to inhalation class Y and all other compounds of the element are assigned to inhalation class W. Promethium, in common with the other lanthanides is primarily concentrated in liver and bone (Stuart, 1964;Gensicke and Nitschke, 1965;Grigorescu and Weber, 1969;Smith, 1972;Gensicke, 1966). In man it is retained in the body with a biological half-life of greater than 1 000 days (Palmer, Nelson and Crook, 1970).…”