Cytogenetic effects of plutonium-239 in male mice

Abstract

INCREASING quantities of plutonium-239 are processed in the nuclear power industry. The likely magnitude of the associated genetic risk is still uncertain but thought to be less than the risk of cancer induction¹. Green et al.² have recently shown, however, that plutonium reaching the testis after intravenous injection of ²³⁹Pu citrate into CBA mice concentrates in the interstitial tissue, outside the seminiferous tubules. They calculated that the average dose rate to spermatogonial stem cells, in which genetic damage can accumulate, was about 2–2.5 times that to the whole testis. In these circumstances, the genetically significant dose is higher than the average tissue dose, which is that normally used for protection purposes¹. To obtain more direct evidence on genetic damage from gonadal plutonium, we are studying the induction of chromosome aberrations in germ cells of male mice after protracted exposure to α particles from ²³⁹Pu. The results of the first experiment, described here, suggest that α radiation has the expected high relative biological effectiveness (RBE)³ for induction of chromosome damage and that a distribution factor of the magnitude proposed may indeed be operating as well.