30232
Both the principal component analysis ( PCA ) of the biomarker data set as well as the biomarker response index ( BRI ) confirmed substantial pollution pressure at the highly polluted sites , and very low pollution exposure at the three reference sites .
 None
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:  
Answer:
 None