292 



A. C. UPTON, M. A. KASTENBAUM, AND J. W. CONKLIN 



was evident. For other types of leiilvaemia (Fig. 11), and ovarian (Fig. 12) and 

 pulmonary (Fig. 13) tumours, the curves more nearly resembled those of the 

 over-all population (Figs. 1-4). 



too 



450 600 

 Age (days) 



1050 



Fig. 13. Age-specific mortality rate of RF female mice dying with pulmonary tumour, 

 as influenced by X-rays, TEM, or HN2 administered early in life (arrow denotes age at 

 treatment). See Methods for doses. 



O Untreated control (26/130 mice); • HN2 (94/160 mice); A TEM (82/157 mice); Q X-ra,y 

 (12/259 mice). 



DISCUSSION 



From these results, it is evident that the life-shortening effect of irradiation 

 in the mouse is correlated with early mortality from non-neoplastic, as well as 

 neoplastic diseases, many of which are otherwise associated with senescence. 

 The non-neoplastic diseases include nephrosclerosis, cardiac thrombosis, 

 enteritis, intussusception, and diverse inflammatory and degenerative changes 

 (see Upton et at, 1960), the pathogenesis and significance of which require 

 further study. 



The incidence of all neoplasms increased with age, except for thymic 

 lymphomas and myeloid leukaemias, which reached a peak at early ages in 

 irradiated animals. The basis for the early induction of radiogenic leukaemias 

 remains to be disclosed, but the possibility that it may be related to viral 

 aetiological factors must be considered. Whether or not the relatively short 

 induction period of radiogenic leukaemia in man (see Upton, 1961) reflects a 

 situation analogous to that in the mouse cannot be decided without further 

 information. 



