Relative Hazards for Inhaled 95 Zr and 95 Nb Particles Formed Under Various Thermal Conditions 1

Summary

Aerosols containing ⁹⁵Zr and ⁹⁵Nb at near-equilibrium were produced at 100, 250, 600, and 1100° to give particles of four different chemical compositions. When inhaled by mice, a differential metabolism of the radionuclides was sometimes observed, dependent upon the temperature of formation. At the two highest temperatures, the deposited particles were retained tenaciously in the lung and maintained the starting ⁹⁵Zr-⁹⁵Nb ratio of ~1.9. At 100°, the radionuclides were translocated from lung to skeleton with a ratio of ~1.3, indicative of an excess burden of ⁹⁵Zr. At 250° the pattern was similar but less pronounced. The differential patterns of retention resulted in significant differences in radiation dose pattern; at the lowest temperature the highest radiation doses were received by skeleton, lung, and liver, while at the higher temperatures the radiation dose was delivered almost exclusively to lung.