18868
These results suggest that P450 2A enzymes , as well as P450 Family 1 enzymes including P450 1B1 , are major enzymes involved in activating PAHs and aryl - and heterocyclic amines , as well as tobacco - related nitrosamines .
 Chemical: PAHs; Chemical: aryl - and heterocyclic amines; Chemical: nitrosamines
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: PAHs; Chemical: aryl - and heterocyclic amines; Chemical: nitrosamines