HEALTH PHYSICS AND RADIATION PROTECTION 



97 



shown no effects. Little or no such information is available for internally 

 deposited radioactivity. Perhaps the only clear-cut knowledge is based 

 on the damage incurred by numerous individuals from ingestion of radium 

 (44). On the basis of the application of a safety factor to these data, the 

 maximum permissible amount of radium 226 in the body has been set at 

 0.1 fic. Since strontium is fixed in the bones similarly to radium, maxi- 

 mum permissible body burdens have been stated as 1 fxc Sr^" and 2 fxc 



Fig. 3-5. Elaborate barrier-aiid-mirror arrangement for handling relatively higli le\t4s 

 of gamma emitters. Note remote-control pipetter. (Courtesy of Atomic Energy 

 Commission.) 



Sr*^, which take into account the decreased biological effectiveness of the 

 Sr beta rays as compared with the Ra alpha rays. 



Although animal experiments have given considerable information as 

 to the pattern of distribution and removal of radioisotopes from the body, 

 they have contributed little directly to the basic problem of potential 

 damage. This is primarily because the delayed effects may not become 

 evident for years and most animal experiments have not been carried out 

 long enough, partly because of the short life span of the usual laboratory 

 animal. In this connection, the very important question as to whether 

 the induction period is a function of life span is still to be answered. That 



