18632
Therefore , to reveal the existence of more permanent alterations of DNA structure after genotoxic stress , the RTG - 2 rainbow trout cell line was exposed for 3days to benzo [ a ] pyrene ( B [ a ] P , 0 . 1 - 10 mu M ) and ethyl methanesulfonate ( EMS , 0 . 1 - 1mM ) followed by 3days of recovery period .
 Chemical: benzo [ a ] pyrene; Chemical: B [ a ] P; Chemical: ethyl methanesulfonate; Chemical: EMS
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: benzo [ a ] pyrene; Chemical: B [ a ] P; Chemical: ethyl methanesulfonate; Chemical: EMS