6399
To do this , the authors quantified Daphnia survival in outdoor test systems ( 0 . 95 L ) exposed to a factorial combination of five Elodea densities crossed with five malathion concentrations .
 malathion
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 malathion