Relative Biological Effectiveness of Internal Emitters

Abstract

The acute and chronic toxicity of a number of internally deposited radioisotopes was studied on CF1 female mice. Pu239, po210, U232, U233, Th228, Ru106, Sr89, Sr90, Y90, p32, and Ca45 were used. All alpha emitters were approximately 20 times as effective as the radium standard Ra226 (on the base of dose injected per unit weight) in killing half of the animals within 20-30 days, while the beta emitters were less effective. A comparison of net average mortality rates from the time of injection to 425 days showed increasing values of relative biological effectiveness with increasing mortality. At the lowest measured rate the ratios were 15:4:1:0.07:0.02 for Pu239, Po210, Ra226, Sr90 and Sr89 respectively. During the first 425 days a preceptible increase in mortality rate with lymphoid tumors was observed in animals treated with Pu239, Ra226, Sr89, Sr90 and Ca45 and a pronounced increase in the cases where Po210, P32 or Y90 had been administered. With respect to induction of bone tumors the ratio 20:1:0.2:0.1:0.05 for Pu239, Ra226, Sr90, Sr89, and Ca45 was found.