Chapter 4 



RELATION BETWEEN NEUTRON DOSE AND THE MORTALITY, 

 BODY WEIGHT AND HEMATOLOGY OF WHITE RATS 



By JAMES L. LEITCH 



INTRODUCTION 



For the past ten years, there has been much interest concerning the 

 action of neutrons on organisms and biological systems. Much of the 

 earlier work to 1944 has been summarized recently by Stone (1). In 

 general, the effects produced by neutrons have been found to be quali- 

 tatively comparable to those produced by X-rays. For equivalent effects, 

 however, Lawrence (2) reports that the X-ray dose varies from 2.5 to 10 

 times that of the corresponding neutron dose when both are measured in a 

 \'ictoreen r chamber. However, there are little or no specific data con- 

 cerning the mechanism of action of neutron rays on biological systems as is 

 also true of X-ra^'s. Other than the fact that the ionization produced 

 by both these types of radiations is responsible in some manner for their 

 effects, nothing definite is known concerning how such ionization in tissues 

 and other biological systems produces the observed changes. Before a 

 detailed study of the mechanism of action of neutrons on biological systems 

 could be initiated, it was deemed advisable to make a fairly comprehensive 

 study of the relationships existing between the neutron dose in whole-body 

 irradiation and the various biological effects such as leukopenia, loss of 

 body weight, erythropenia, etc., comparable to that made by Henshaw 

 (3) on Roentgen injuries. 



Lawrence and Lawrence (4) found that for albino rats (2.5 to 3 months 

 old) of the Wistar Strain neutron doses of 14 to 42 r produced a decrease 

 in leukocytes together with an increasing proportion of polymorphonuclear 

 leukocytes which became greater as the dose was increased. In this range, 

 the rats showed a definite leukopenia with recovery without showing any 

 signs of illness. Two rats of this age-group died: one on the 11th day 

 after 72 r with an increase in the red blood cell count from 9.60 X 10*^ up 

 to 13.00 X 10'' and the second on the 9th day after 100 r. Just prior to 

 death both of these rats showed a white blood cell count increasing after 

 a minimum on about the third day together with necrotizing lesions of the 

 head, the latter being due probably to secondary infection. On the 5th 

 day, both of these animals were obviously sick with rough fur and arched 

 back, did not eat or drink and lost weight. 



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