23969
Two - month - old mice were exposed to gamma - rays at a dose of 8 , 6 . 5 , or 5 Gy for a30 - day survival study , endogenous spleen colony formation , or other experiments , respectively .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None