Priest, N. D. Comparative Biokinetics of Trivalent Radionuclides with Similar Ionic Dimensions: Promethium-147, Curium-242 and Americium-241. Radiat. Res. 168, 327–331 (2007).

Data on the distribution and redistribution patterns in the laboratory rat of three trivalent elements with a similar ionic radius have been compared. This showed that these distributions for the two ions with the same ionic radius (111 pm), i.e., those of promethium (a lanthanoid) and curium (an actinoid), were indistinguishable and that americium, with a slightly larger ion size (111.5 pm), behaved similarly. The results are consistent with the suggestion that ion size is the only important factor controlling the deposition and redistribution patterns of trivalent lanthanoids and actinoids in rats. The result is important because it suggests that the same radiological protection dosimetry models should be used for trivalent actinoids and lanthanoids, that human volunteer data generated for lanthanoid isotopes can be used to predict the behavior of actinoids with the same ion size, and that appropriate pairs of β-particle-emitting lanthanoid and α-particle-emitting actinoids could be used to study the relative toxicity of α and β particles in experimental animals.