Genetic effects of testicular incorporation of 137Cs in mice.

A comparative estimation of the frequencies of genetic disorders induced in germ cells of male mice by a single or long-term exposure to incorporated 137Cs or to external gamma-radiation has been carried out. The frequencies of dominant lethal mutations induced by a single exposure were similar with both types of radiation. In stem cell spermatogonia the frequency of reciprocal translocations was significantly lower in the case of single 137Cs administration than upon external gamma-radiation. Upon long-term administration the genetic efficiencies of both types of radiation were similar.

Genetic effects of 131I in reproductive cells of male mice.

A study was made of the frequencies of dominant lethal mutations (DLM) in pre- and post-meiotic germ cells, reciprocal translocations (RT) in spermatogonia and abnormal sperm heads (ASH) induced by a single intraperitoneal administration of Na131I with an activity of 1.48-740 kBq/g to male mice. The frequency of DLM was shown to increase only when postmeiotic cells were exposed to the radionuclide. The RT frequency increased insignificantly with increases in the dose of 131I. The ASH frequency increased only when maximal doses of 131I were administered. The relative biological efficiency (RBE) of 131I with reference to the indices under study is less than 1.

Evaluation of the genetic effects of 238Pu incorporated into mice.

The genetic effects of 238Pu incorporated into male mice were estimated by several tests. The activity of the administered 238Pu nitrate varied from 7 to 1850 Bq/g of body weight. The average alpha-radiation dose absorbed in the testes ranged from 2 to 96 cGy, with a dose rate of 0.004-1 cGy/day. alpha-Radiation from 238Pu was shown to induce dominant lethal mutations (DLM) and reciprocal translocation (RT), chromosomal fragmentation and formation of abnormal sperm heads (ASH). The effect does not depend on the average alpha-radiation dose absorbed in the testis. The relative genetic efficiency of alpha-radiation, as compared with that of chronic alpha-radiation for the indices under study, was about 10-20.

Carcinogenic effects in rat progeny exposed perinatally to radionuclides.

The distribution of two transuranic elements, plutonium and americium, in pregnant rats and in their fetuses, and the carcinogenic effects seen in progeny exposed perinatally are discussed. The appearance of malignant tumours in the liver and skeleton corresponds to the pattern of deposition of these radionuclides in the body.

Genetic effects of radiocarbon in reproductive cells of male mice.

The genetic effect of incorporated radiocarbon was studied after single, long-term (33 days) and chronic (6 and 12 months) treatment of male mice (CBA X C57B1) F1 with [14C]glucose. The genetic effect in male germ cells was estimated by 3 tests: DLM frequency in post- and pre-meiotic cells, RT frequency in stem spermatogonia and frequency of abnormal sperm heads. Absorbed doses in the gonads were: 0.22, 0.50 and 1.01 Gy, after a single exposure; 0.74 and 1.47 Gy, after long-term exposures; and 0.006 and 0.031 Gy, after chronic exposure for 6 months; and 0.013 and 0.066 Gy, for 12 months. The results suggest that DLM frequency in post-meiotic cells increased linearly with increasing the dose of 14C single and long-term exposures at a dose of 1.47 Gy only. A chronic treatment with [14C]glucose induced no increase in DLM frequency. RT frequency in stem spermatogonia was statistically significantly higher than the control level after the single and long-term exposure to 14C. A comparison of the results with the results of external single and chronic gamma-irradiation allows the conclusion that the relative genetic efficiency of radiocarbon as compared with that of gamma-rays is about 1.