3260
In addition , PFOS increased early thyroid development gene ( hhex and pax8 ) expression in a concentration - dependent manner , decreased steroidogenic enzyme gene ( CYP17 , CYP19a , CYP19b ) expression , and changed the expression pattern of estrogen receptor production genes ( esr1 , esr2b ) after 500 micro g / L PFOS treatment in zebrafish embryos .
 Chemical: PFOS; Chemical: estrogen; Chemical: PFOS
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: PFOS; Chemical: estrogen; Chemical: PFOS