23403
To assess the involvement of copper in PCB toxicity , male Sprague - Dawley rats were fed an AIN - 93G diet with differing dietary copper levels : low ( 2 ppm ) , adequate ( 6 ppm ) , and high ( 10 ppm ) .
 Chemical: PCB; Chemical: copper
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: PCB, copper 
Answer:
 Chemical: PCB; Chemical: copper