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Gerontology. 1998;44(5):272-6.

Effect of a continuous gamma irradiation at a very low dose on the life span of mice.

Author information

1
Laboratoire d'Histologie-Embryologie-Cytogénétique, Faculté de Médecine Toulouse-Rangueil, Toulouse, France. caratero@cict.fr

Abstract

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.

PMID:
9693258
DOI:
10.1159/000022024
[Indexed for MEDLINE]

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