HEALTH PHYSICS AND RADIATION PROTECTION 99 



currents or contamination of the surfaces of shoes or ecjuipmcnt. Some 

 specific suggestions will be found at the end of this chapter. 



Classification of Radioisotopes. Table 3-6 presents a listing of various 

 radioisotopes subdivided according to the relative internal hazard (5). 

 The relative radiotoxicity was obtained from a consideration of the follow- 

 ing factors: (a) half-life, (b) energy and character of radiation, (c) degree 

 of selective localization in the body, (r/) rate of elimination, and (e) quan- 

 tities usually employed and modes of handling. 



Table 3-6. Hazard from Absorption into the Body 



Group I Group II Group III 



Slight hazard Moderately dangerous Very dangerous 



Na^S" K« Cu«^ Mns^," H^, C", P^^, Na",'' S3^ CP^ Ca«, Fe", Sr^", Y"', Zr^^ « 

 As'6,° As", Kr»^ Hgi97" Mn^*," FeS9," Q^^oa g^sg^ q^i", Pmi«, Bi^" 



Nb^^«Rul''^«Rulo^ Te^", 

 Tei29, 1131, Csi",° Bai",'' 

 La""." Ce"i, Pri« Nd""," 



^^|198 a J^^199 a J^g.203,205 



" Principal gamma emitters. 



(From "Control and Removal of Radioactive Contamination in Laboratories," 

 Natl. Bur. Standards Handbook 48, Dec. 15, 195L) 



Decontamination. The use of rubber gloves and individual pans 

 underneath all equipment will usually eliminate the necessity for rigorous 

 decontamination procedures on either skin or laboratory surfaces. How- 

 ever, the following suggestions, taken mainly from (5), are listed for pur- 

 poses of reference: If the exact nature of the contaminant is known, some 

 specific reagent may be chosen for the most effective decontamination. 

 In general, with a Geiger-AIuller counter of about 2-in.- flat window area 

 placed as close as possible to the contaminated area or to the contam- 

 inated skin, group I and II radioistopes should be reduced to a level of 

 less than 1000 counts/min, and group III to less than 100 counts/min. 

 It is sometimes helpful to wipe a suspected surface with slightly moistened 

 filter paper that can then be counted to test for removable contamination. 



General Hand Washing: 



1. Wash for not less than 2 min or more than 3 min by the clock with a 

 mild pure soap in tepid water with a good lather, covering the entire 

 affected area thoroughly. Give special attention to areas between the 

 fingers and around the fingernails. The outer edges of the hands are 

 readily contaminated and often neglected in washing. Do not use highly 

 alkaline soaps or abrasives. Rinse thoroughly and repeat, as monitoring 

 indicates, until the desired degree of decontamination is achieved, but not 

 exceeding three or four times. 



2. If the above procedure is not sufficiont to remove the contamination, 



