Satow Y, Lee J Y, Hori H, Okuda H, Tsuchimoto S, Sawada S, Yokoro K
J Radiat Res. 1989 Jun;30(2):155-63. doi: 10.1269/jrr.30.155.
The teratogenicity of californium-252 (Cf-252) irradiation which generates approximately 70% 2.3 MeV fast neutron and 30% gamma rays was evaluated. A single whole body exposure of Cf-252 at various doses was given to pregnant rats on day 8 or 9 of pregnancy, followed by microscopic autopsy of the fetuses at the terminal stage of pregnancy to search for external and internal malformations. For comparison, pregnant rats were irradiated with various doses of cobalt-60 (Co-60) standard gamma rays at the same dose rate (1 rad/min.). The doses were 20-120 rad of Cf-252 and 80-220 rad of Co-60. Using frequency of radiation induced malformations observed on day 8 of pregnancy as an index, relative biological effectiveness (RBE) of 2.3-2.7 was obtained from the straight line obtained by modifying by the least squares method the frequency curves of malformed fetuses in total implants and in surviving fetuses. The types of malformations induced by Cf-252 and Co-60 irradiation were alike. Using fetal LD50 as an index, 2.4 was obtained as RBE when irradiated on day 8 of pregnancy and 3.1 as that when irradiated on day 9. The results showed that Cf-252 had stronger a teratogenic effect than Co-60 gamma rays.
对产生约70%的2.3兆电子伏快中子和30%伽马射线的锎 - 252（Cf - 252）辐射的致畸性进行了评估。在妊娠第8天或第9天，对怀孕大鼠进行单次全身不同剂量的Cf - 252照射，然后在妊娠末期对胎儿进行显微镜解剖，以寻找外部和内部畸形。作为对照，以相同剂量率（1拉德/分钟）用不同剂量的钴 - 60（Co - 60）标准伽马射线照射怀孕大鼠。Cf - 252的剂量为20 - 120拉德，Co - 60的剂量为80 - 220拉德。以妊娠第8天观察到的辐射诱发畸形频率为指标，通过最小二乘法修正总植入胎儿和存活胎儿中畸形胎儿的频率曲线得到的直线，得出相对生物效能（RBE）为2.3 - 2.7。Cf - 252和Co - 60照射诱发的畸形类型相似。以胎儿半数致死剂量（LD50）为指标，妊娠第8天照射时RBE为2.4，妊娠第9天照射时为3.1。结果表明，Cf - 252的致畸作用比Co - 60伽马射线更强。
