95Zr-95Nb in Human Lungs from Fallout

Abstract

The presence of easily measurable quantities of intermediate-lived fission products in ground level air during the first half of 1963 prompted an investigation of the distribution of gamma emitting nuclides in human lungs. Lungs from five cadavers were dissected, ashed and measured for 95Zr-95Nb, 13'Cs and 40K using a 4 x 4411. NaI well crystal and a multichannel analyzer. Prior measurement of the cadavers in a whole body counter using a 8 x 4-in.NaI crystal positioned over their backs, permitted calibration of a low level in situ method of measuring 95Zr-95Nb in human lungs. Counting efficiencies ran from 3 x to 6 x 10-2 counts/dis. in the full energy peak. The measured lung burdens ranged from 210 to 450 pc at the time of death and were comparable to the values expected from the ICRP model for insoluble materials. The distribution in the lobes was fairly uniform.

Zirkonium und seine Verbindungen [MAK Value Documentation in German language, 1998]

“…65 Tagen (Cofield 1963;Wrenn et al 1964). Die Halbwertszeit, bezogen auf die Gesamtkörperspeicherung, beträgt beim BeagleHund 328-365 Tage (Waligora 1971).…”

Sources of Radioactive Pollution

“…Wrenn et al (28) have shown that during periods of weapons testing, 95 Zr and its radioactive daughter, 95 Nb are present in human lungs and can be measured in vivo using a sodium iodide crystal positioned directly in contact with the chest. In New York City, where their measurements were made, Wrenn and his associates found that the dose to the lungs was about 3 μ-rad/day from this pair of isotopes.…”

Deposition and Retention of Inhaled Niobium in Beagle Dogs

“…Previous studies of fallout 9sZr-95Nb in ZNbm , 93 Nb", "b, %Nb", 95Nb and 95Nbm are humans have shown most of the radioactivity to be contained in the lungs (Ru62;Ru65;Os63;Wr64;Du66). This indicates that ifihalation was the major exposure route.…”

“…Niobium-95 is also the daughter product of radioactive 95Zr decay. Since both of these isotopes are abundant fission products, they are commonly found together in particulate material released from fission processes (Har64; Wr64;Du66). Radioactive decay of 95Nb occurs by beta emission Niobium metal is a very refractory material and has been suggested for use in structural components of fusion reactor systems.…”

“…Studies of the retention of 9sZr-95Nb in the lungs of humans exposed to fallout reported half-times similar to this ( 0~6 3 ; Ru65; Du66). A shorter half time of 67 days for 9SZr-95Nb from fallout has also been suggested (Wr64). The Task Group on Lung Dynamics (ICRP66) recommended a biological half time of 90 days for both niobium oxides and halides in the lung.…”