4303
METHODS : For one severely affected worker liver biopsy and immunohistochemical stainings for the presence of trifluoroacetyl protein adducts were done .
 trifluoroacetyl
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 trifluoroacetyl