HEMATOLOGIC EFFECTS OF RADIATION 



1043 



normal limits is observed in all groups exposed to total-body dosages 

 below 128 n. 



The number of lymphocytes in the peripheral blood is reduced after 

 the administration of doses ranging from 9-128 n. This reduction is 

 apparent as early as 3 hours after exposure, with a maximum reduction at 

 2-3 days. Although the lymphocyte values of animals exposed to 9 n are 

 again within the normal control range by 5 days, the lymphocytes of those 

 animals exposed to 26 n and above remain below control values for more 

 than five weeks. 



10,000 



5000 



2000 



CO 



> 

 o 

 o 



i 



CL 



1000 



500 



200 - 



100 



C 



10 15 20 



TIME FROM EXPOSURE. 



25 

 days 



30 



-• CONTROLS 



-a 9n 

 -* 26n 



®— — o 55n 



e e 68n 



a — — » 76n 



o o 89n 



35 



-o 97n 

 -« I06n 

 -• I28n 



Fig. 16-9. Effect of single doses of fast neutrons on the lymphocyte values of the 

 peripheral blood of rabbits. 



A severe normochromic anemia is observed in animals exposed to a 

 fast-neutron LD 5 o- The maximum anemia, as is also observed after 

 exposure to a 30-day LD 50 of X radiation, appears between the fourteenth 

 and sixteenth days after exposure. Recovery to normal values occurs by 

 23 days. Reticulocytes are reduced to 0.1 per cent or less by the third 

 day in animals exposed to doses of 128 fast-neutron units or above. 



After doses of 80-89 and 100 108 n, a maximum reduction of approxi- 

 mately 72 per cent in the platelet values of the peripheral blood occurs 

 between the fifth and tenth day, with return to normal values by 15 and 

 23 days, respectively, in the two exposure levels. 



An abortive rise in heterophils and lymphocytes occurs (between the 



