Revision 1
March 19, 1998

by Radiation, Science, and Health, Inc.,
Edited by J. Muckerheide

1.3
Animal & Plant Biology

1.3.1
Mammals

References

"A survey made at the ground level in South-West France reveals that the gamma radioactivity ranges generally from 0.001 to 0.030x10^-2 mGy/hr and that dose rates as high as 1x10^-2 mGy/hr are not uncommon."

"To study the production of chromosome aberrations in mammalian somatic cells, male laboratory rabbits were kept, for 20 months, in plastic cages placed on the floor and gamma ray dose determined by individual fluoride dosimeters put around the neck of each rabbit....During the 20 months the exposed rabbits received from 36,300 up to 130,750 mGy according to the locations of their cages in the hut, whereas the doses received during the same period by the controls amounted to 2,400 mGy.

"Figure 5 shows that the yield of structural chromosome anomalies typical of an exposure to ionizing radiation (chromosome fragments, dicentric chromosomes) increase initially but disappear completely after 20 months."

"The male mice maintained in the area of high natural radioactivity received from 13,800 mrad up to 63,250 mrad and the concurrent controls from 34 to 127 mrad according to the duration of exposure."

"The number of litters and of offspring sired after exposure during 6 month period was clearly related to the dose of gamma irradiation received during the exposure period (Fig. 6). Both values increase in a dose-related way up to 45,080 and fall abruptly for the animals receiving 63,250 mrad.

"The histological and cytological studies performed on the testes at the end of the mating period did not reveal any difference between the control and the exposed males."

"Our observations confirm that high natural radioactivity can result in the production of structural aberrations in mammals living in those areas.....

"...It can be inferred, therefore, that one cannot consider that cytogenetic observations performed on wild mammals living in area of high radioactivity (natural or resulting from nuclear assays) would provide reliable information on the doses received by the animals and on the level of damage produced to their genetic material.

"The increase in male fertility observed for animals receiving up to 43,000 mrad could represent an example of radiation hormesis (Gerber 1994): stimulating effects of small doses of ionizing radiations is a controversial topic but it should be stressed that our results on the male mice are in agreement with the observations of Newcombe and McGregor (1972) who reported an increase of embryo production after low doses of ionizing radiations administered to trout spermatozoa."