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The bioaccumulation of saxitoxins ( STX ) in the trophic chain , mainly in freshwater , are not completely known .
 Chemical: saxitoxins; Chemical: STX
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: saxitoxins; Chemical: STX