PART V 

 AGING AND RADIATION DAMAGE 



A FEATURE of our timcs is that people are now living long enough so that the prob- 

 lems and diseases of the aged have become an important medical speciality, 

 and at the sam.e time we are, of necessity, embarking on the development of civil 

 and military technology which generates radioactivity, an agent which, uncon- 

 trolled, will contribute to shortening our lives. There is evidence that these two 

 attributes of this age are more than incidentally related. 



It is well for us to remember that the biological effects of radiation are not 

 new, for the same radiation by which Becquerel discovered radioactivity very 

 soon thereafter burned his person. An understanding of these effects has come 

 slowly. The relationship between aging and radiation damage has been dormant 

 in the literature for a long time and has come to prominence only recently. 



The first papers on the effect of radiation on life span were published by 

 W. P. Davey (1, 2) in 1917 and 1919. The care exercised in dosimetry and in 

 showing that the observed effect is due to the x-rays and not to some experi- 

 mental artifact was most remarkable for the time at which this work was done. 

 Davey found that the life span of the beetle Tribolhim confusiun was shortened 

 by large amounts of x-rays and lengthened slightly by small amounts. The first 

 result seems to be well established today. The second result is still frequently 

 reported. 



GowEN and Stadler (3) in 1952 found an increased life span for male 

 Drosophila melanogaster given 2500 r, although the life span of the female was 

 decreased. The effect appeared in Lorentz's data (4) on the LAF^ mouse and 

 inbred guinea pigs receiving 0.1 1 r per day. He did not consider this statistically 

 significant, although Sacher (5) later stated that the effect is significant and that 

 it had been confirmed by himself and D. Grahn. Gowen (6) found a shortening 

 of the life span in male mice from ten distinct inbred strains — even for small 

 single doses of x-rays. However, for female mice he found an increase in life 

 span for doses up to 320 r. But the number of litters produced was reduced even 

 for small doses. The explanation given was that the semi-sterility induced by 

 x-rays reduced the hazards of pregnancy. For low doses, it was argued, this 

 more than compensated for the somatic x-ray damage. 



It is not generally accepted that there is a stimulation due to x-rays. Probably 

 cases where this seems to occur can be explained as an artifact, perhaps following 

 Gowen's explanation. At any rate further research on this point is well justified. 



In 1937 Russ and Scott (7) published a report on the biological effects of 

 continuous gamma irradiation. They found the significant features known 

 today, namely, that there is a cumulative permanent damage reflected by a death 

 rate higher than that of the controls, sterility or semi-sterility, high infant and 

 prenatal mortality of progeny from both male and female irradiated parents. 

 They confirmed these results in 1939 and specifically called attention to 

 accelerated aging in the irradiated rats (8). 



The invention of the nuclear reactor in 1942 added immensely to the industrial 

 and laboratory hazards of radiation and to the concern for evaluating these 

 hazards. Henshaw (9) in 1944 again called attention to the similarity between 

 the pathology of aging and the pathology of radiation damage. Sacher (10) 



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