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To test the hypothesis , we determined the potency and mechanism of inhibition for styrene and its metabolites toward oxidation of 4 - nitrophenol using CYP2E1 Supersomes (R) and human liver microsomes .
 styrene, 4 - nitrophenol
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 styrene, 4 - nitrophenol