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Mutational repair in mammals and its bearing on risk assessment

Conference ·
OSTI ID:6691163
Most of the genetic risk from radiation in humans will involve germ cell stages that are of long duration, namely, the spermatogonial stem cells in the male and the oocytes in the female. Mutagenic studies in the mouse that are concerned with risk assessment have, therefore, concentrated on these stages. The first evidence that some repair of mutational damage could occur came from investigations with the specific-locus method in the mouse in which it was shown that when a given dose of radiation was spread out evenly over a few weeks, fewer mutations would be obtained than when the same total dose was delivered in a few minutes. In spermatogonia, exploration of the effects of a wide range of radiation dose rates showed that at a dose rate of 0.8 R/min the mutation frequency is only /sup 1///sub 3/ to /sup 1///sub 4/ of that for the same total doses at 90 R/min. At intermediate dose rates the mutation frequencies are also intermediate. However, when the dose rate is lowered to 0.009, 0.001, or to 0.0007 R/min there is no further reduction in mutation rate below that observed at 0.8 R/min. In oocytes, the mutation frequency depends on the stage of oocyte development. The important stage, so far as human genetic hazards are concerned, is the one of longest duration, namely, the arrested immature oocyte. In extensive radiation experiments in the mouse, this stage has never produced a mutation frequency higher than that in the controls.
Research Organization:
Oak Ridge National Lab., TN (USA)
Sponsoring Organization:
USDOE
DOE Contract Number:
W-7405-ENG-26
OSTI ID:
6691163
Report Number(s):
CONF-770663--2
Country of Publication:
United States
Language:
English

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Related Subjects

560152* -- Radiation Effects on Animals-- Animals
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ACUTE EXPOSURE
ACUTE IRRADIATION
ANIMALS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
BIOLOGICAL VARIABILITY
CHRONIC EXPOSURE
CHRONIC IRRADIATION
DOSE RATES
DOSE-RESPONSE RELATIONSHIPS
DOSES
EXTRAPOLATION
FEMALES
GAMETES
GENETIC EFFECTS
GENETIC RADIATION EFFECTS
GENETIC VARIABILITY
GERM CELLS
IRRADIATION
MALES
MAMMALS
MAN
MICE
MUTATIONS
NUMERICAL SOLUTION
OOCYTES
PRIMATES
RADIATION DOSES
RADIATION EFFECTS
RADIOINDUCTION
RADIOSENSITIVITY
RECOVERY
REPAIR
RODENTS
SPERMATOGONIA
VERTEBRATES