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We previously demonstrated that developmental exposure to a mixture of polychlorinated biphenyls ( PCBs ) which was reconstituted according to the congener pattern found in human breast milk caused feminization of sweet preference as a sexually dimorphic behavior in adult male rats , following decreases in aromatase activity in the brain of newborn male pups .
 Chemical: polychlorinated biphenyls; Chemical: PCBs
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: polychlorinated biphenyls; Chemical: PCBs