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While PBDEs and OH - BDEs have been shown to inhibit the activity and expression of deiodionases , a family of enzymes that regulate thyroid hormone concentrations intracellularly , it is unclear whether or not they can affect regional expression of the different isoforms during early development .
 Chemical: PBDEs; Chemical: OH - BDEs; Chemical: thyroid hormone
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: PBDEs; Chemical: OH - BDEs; Chemical: thyroid hormone