Kidney Disease in Beagles Injected with Polonium-210

An unusually high incidence of kidney disease (tubular degeneration and necrosis with fibrous replacement) was observed among 24 beagles injected at about 5 years of age with 116 or$329\ {\rm kBq}\ {}^{226}{\rm Ra}\ {\rm kg}^{-1}$ but not among an additional 10 beagles given about$329\ {\rm kBq}\ {}^{226}{\rm Ra}\ {\rm kg}^{-1}$. This²²⁶ Ra solution also contained${}^{210}{\rm Pb},\ {}^{210}{\rm Bi}$, and²¹⁰ Po. To determine whether the kidney disease was related to the radiation from²²⁶ Ra and its short-lived progeny or to the α radiation from²¹⁰ Po, 2 beagles about 7 years of age were injected with 451 kBq${}^{226}{\rm Ra}\ {\rm kg}^{-1}$ from which the${}^{210}{\rm Pb},\ {}^{210}{\rm Bi}$, and²¹⁰ Po had been removed, and 4 other beagles about 7 years of age were injected with$122\ {\rm kBq}\ {\rm kg}^{-1}$ of²¹⁰ Po citrate. Measurements of polonium retention in the kidneys of these dogs and of bismuth retention in the kidneys of 4 additional beagles given${}^{210}{\rm Bi}$ citrate enabled us to model the retnetion of these emitters in the dog kidney and to estimate the kidney dose from the α radiation of²¹⁰ Po following injection of either${}^{226}{\rm Ra}+{}^{210}{\rm Bi}+{}^{210}{\rm Po}$ or²¹⁰ Po only. Autoradiography revealed that almost equal concentrations of²¹⁰ Po were in the tubular epithelium and/or its basement membrane and in the glomeruli, but very little of the${}^{210}{\rm Bi}$ deposited in kidney tissue was present in the glomeruli. Radiation damage to the kidneys similar to that observed previously in beagles given²²⁶ Ra solutions that also contained${}^{210}{\rm Bi}$ and²¹⁰ Po was seen among the beagles given²¹⁰ Po but not in the dogs given purified²²⁶ Ra. The analysis of these data indicated that the relatively high incidence of kidney disease among the mature beagles injected with²²⁶ Ra and its accompanying${}^{210}{\rm Bi}$ and²¹⁰ Po resulted from α irradiation of the kidneys by the substantial amount of²¹⁰ Po that was in the injection solution.