Effect of a Continuous Gamma Irradiation at a Very Low Dose on the Life Span of Mice

Background: There is epidemiological evidence that suggests there are beneficial effects of ionizing radiation at low doses. Some experimental studies confirmed this hormetic effect with doses of about 1 cGy/day, but no data concerning very low dose rates are available. Objective: The aim of this st...

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Bibliographic Details
Published in:Gerontology (Basel) 1998, Vol.44 (5), p.272-276
Main Authors: Caratero, A., Courtade, M., Bonnet, L., Planel, H., Caratero, C.
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Biological effects of radiation
Dose-Response Relationship, Radiation
Experimental Section
Female
Fundamental and applied biological sciences. Psychology
Gamma Rays
Ionizing radiations
Longevity - radiation effects
Mice
Mice, Inbred C57BL
Survival Analysis
Tissues, organs and organisms biophysics
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Summary:Background: There is epidemiological evidence that suggests there are beneficial effects of ionizing radiation at low doses. Some experimental studies confirmed this hormetic effect with doses of about 1 cGy/day, but no data concerning very low dose rates are available. Objective: The aim of this study was to determine the life span of mice exposed to very low doses of ionizing radiation. Methods: Six hundred female C57BL/6 mice, 1 month old, were exposed to chronic gamma irradiation at very low dose rates of 7 or 14 cGy/year. These doses are about 25 or 50 times higher than background, but much lower than the doses of about 1 cGy/day used in previous experiments. Three hundred mice living in the same room were used as controls. Results: The life span, after the beginning of the experiment, determined by the survival time of 50% of each population, is increased in irradiated mice: 549 days in controls, 673 days in both irradiated groups. The differences are significant between the control and the irradiation mice. Differences between mice irradiated with 7 or 14 cGy are not significant. Conclusions: These results confirm the possibility of a nonharmful effect (hormesis) of ionizing radiation. They demonstrate that the paradigm, which states that low-dose effects can be predicted high-dose effects, cannot be systematically applied in radiation biology in general and gerontology in particular.
ISSN:0304-324X
1423-0003
DOI:10.1159/000022024