XVII. 



R A D I O A (• T I V E T U A C E R S 



645 



necessary are likely to differ and to ('hanfj;e as more experience is ob- 

 tained. At the present time a national body, the National Commit- 

 tee on Radiation Protection {68), and sectional bodies such as one rep- 

 resenting the thirty Midwest institutions that co-operate with the Ar- 

 oonne National Laboratory are drafting i-egulations on the safe han- 

 dling of radioisotopes, including laboratory design {61). Since these 

 regulations are not in a final state anything said now may become ob- 

 solete. Eventually some such body of regulations will apply to any- 

 one desiring to work in this field. The consideration that needs to be 

 given to laboratory design is highly dependent upon the nature and 



ACTIVITY SCALE 



Slight Hazard 



Na"*, K", Cu^S Mnfi2*. As"*, 

 As", Kr«5, H«i!"* 



Moderately Dangerous 



H3, P32, Na"*, SS5, CPe, Mn^^*, 

 Fess*. Cosn*, SrS', Cd^s*, Ru'cs*, 

 Rui»6, Te"', TeiM, Ii3i_ Cs'^'*, 

 Ba'^o* Lai«*, Ce'", Pr'is, 

 Nd'"*, An"'*, All'"*, Hc"'^'^*'' 



Very Dangerous 

 C", Ca«, Fe65, Sr^o, Y^i, 

 Zr's*, Ce'". 611", Bi'io 



10 100 

 fLC. fi.c. fj.c- mc mc. mc. curie 



ACTIVITV TO BE HANDLED IN LABORATORY 



I 

 mc 



10 

 mc. 



100 

 mc. 



Fig. 15. Toxicity levels of selected radioisotopes {68). 



Effective radiotoxicity is obtained from a weighting of the following fac- 

 tors : (a) half-life, {b) energy and character of radiations, (c) degree of selec- 

 tive localization in the body, {d) rates of elimination, and (e) quantities in- 

 volved and modes of handling in typical experiments. The slant boundaries 

 between levels indicate borderline cases and emphasize that there is no sharp 

 transition between the levels and the associated protection techniques. The 

 principal 7-ray emitters are indicated by asterisks {e.g., Na^^*). 



amount of the particular isotopeS to be handled, in addition to the 

 type of work to be done. The amounts of activities of various sorts 

 that will be required for different operations and processes are shown 

 in Figure 14 {66). 



