"Low Level
Radiation Health Effects: Compiling  the Data"

Revision 1
March 19, 1998

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

1.9
Conclusions

"Since the 1960s, (hormetic) effects have been ignored in radiation protection practice, while research on stimulating and adaptive effects of radiation, the radiation hormesis, has continued over several decades. The results of more than 1200 published papers on hormesis were recently reviewed by Luckey (1990) - many of them in an excellent book by Kondo (1993). The studies on hormesis were also presented at four international conferences (Oakland CA 1985, Frankfurt Germany 1987, Kyoto Japan 1992, and Changchun China, 1993). It is astonishing, however, that even recently the obvious hormetic effects appearing in the epidemiological studies were often not noticed, not only by the readers, but by the authors themselves.’ [Ed. note: See for example Section 3.4, Pollycove 1994, Figure 4].

"Radiation hormesis goes beyond the notion that radiation has no deleterious effects at small doses; at small doses new stimulatory effects occur that are not observed at high doses and these new effects may be beneficial to the organisms.

"Recognition of the existence of hormesis opens up an important new field of research.

"In mammals, radiation hormesis enhances defense reactions against neoplastic and infectious diseases, increases longevity and improves fertility . . . in an experiment with mice the incidence of leukemia, cancers, and sarcomas was lower in animals irradiated with cesium-137 gamma radiation doses of 2.5 to 20 mSv than it was in non-irradiated controls. The number of all malignant neoplasms in animals exposed to a single dose of 10 mSv was more than 30% lower than in non-irradiated controls. In several experiments, small initial radiation doses have been shown to improve the survival of animals subsequently irradiated with large, near lethal doses. In other experiments, an increased life span was found in animals irradiated with doses between 250 and 3000 mSv. . . . a group of French studies started in the early 1960’s, indicate that protozoa and bacteria exposed to artificially lowered levels of natural radiation demonstrate deficiency symptoms expressed as dramatically decreased proliferations. This indicates that ionizing radiation may be essential for life."