12245
Oxidative and nitrosative stress and apoptosis in oral mucosa cells after ex vivo exposure to lead and benzo [ a ] pyrene .
 Chemical: benzo [ a ] pyrene
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: benzo [ a ] pyrene 
Answer:
 Chemical: benzo [ a ] pyrene