THE PROBLEM OF THE RELATIVE BIOLOGICAL EFFICIENCY OF VARIOUS TYPES OF RADIATION UNDER CHRONIC EXPOSURE (in German)
For the calculation of the rem-doses'' of a certain type of radiation, it is necessary to know its relative bioiogical efficiency (RBE) to gamma rays. The RBE of dense ionizing radiation, especially neutrons, has very often been measured after acute exposures; comprehensive experiments about RBE values after chronic radiation exposure have been published only during the last years. A survey on these experiments is given, to provide a basis for the determination of the RBE values for the radioprotection of men. This summary mainly deals with the effect of neutrons. The RBE values of neutrons are normally not higher than 5 for acute effects on animals. Also, the RBE of neutrons for the late effects after a single exposure is not much higher, i.e., shortening of life span, lens opacities, carcinogenesis and damages in fertility. The RBE values for somatic effects of irradiation after fractionated or chronic exposure are also described. By fractionation the RBE of neutrons is increased up to 15. These high RBE values are due to the fact, that the effects of gamma rays are mostly reversible, whereas the effects of neutrons are mostly irreversible. Further, the recovery rate from neutron effects is lower than from the effects of gamma rays. Theoretical considerations show, that the RBE of neutrons is doubled, if neutron radiation is given in fractionated exposure as compared to single exposure. For cytoiogical radiation effects, for instance, mitotic delay or chromosome aberrations, much higher RBE values are reported. However the results reported on by different authors vary a great deal. To consider the RBE of neutrons for genetic effects, it is necessary to distinguish between the dominant lethal mutations caused by chromosome aberrations and the recessive point mutations. For the dominant lethals RBE values of neutrons are reported between 4 and 6 and for the recessive lethals between 1 and 2. For other recessive point- mutations, no reliable RBE values are reported. The variability of RBE values under different experimental conditions is shown. (auth)
- Research Organization:
- Universitat Freiburg i. B.
- NSA Number:
- NSA-17-001665
- OSTI ID:
- 4764585
- Journal Information:
- Atomkernenergie (West Germany) Merged with Kerntechnik to form Atomkernenerg./Kerntech. Acta Radiol. Changed to Acta Radiol.: Oncol., Radiat. Phys., Vol. Vol: 7; Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- German
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Genetic effects of neutrons in mammals and their implications for risk assessment in man
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Related Subjects
ANIMALS
BIOLOGY
BODY
CARCINOGENESIS
CHROMOSOMES
ENVIRONMENT
EYES
GAMMA RADIATION
GENETICS
IRRADIATION
LENSES
LETHAL DOSE
MAN
MATHEMATICS
MEASURED VALUES
MITOSIS
MPD
MUTATIONS
NEUTRONS
QUANTITATIVE ANALYSIS
RADIATION DOSES
RADIATION EFFECTS
RADIATION INJURIES
RADIATION PROTECTION
RBE
RECOVERY
SAFETY
STANDARDS