8117
One - twentieth the LC50 concentration , equivalent to the level of concern ( 0 . 38 micro g / L ) for endangered species , was exceeded 31 % of the time during the present study .
 None
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