23401
Aryl - hydrocarbon receptor ( AhR ) agonists , including the most potent polychlorinated biphenyl ( PCB ) congener , 3 , 3 ' , 4 , 4 ' , 5 - pentachlorobiphenyl ( PCB126 ) , increase copper levels in rodent livers .
 Aryl - hydrocarbon, polychlorinated biphenyl, PCB, 3 , 3 ' , 4 , 4 ' , 5 - pentachlorobiphenyl, PCB126, copper
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Aryl - hydrocarbon, polychlorinated biphenyl, PCB, 3 , 3 ' , 4 , 4 ' , 5 - pentachlorobiphenyl, PCB126, copper