20146
Crotonaldehyde , a highly toxic alpha , beta - unsaturated aldehyde , is a major component of cigarette smoke and a ubiquitous environmental pollutant .
 Chemical: Crotonaldehyde; Chemical: alpha , beta - unsaturated aldehyde
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: Crotonaldehyde; Chemical: alpha , beta - unsaturated aldehyde