15676
Relative to cattle 1 . 5 - 2 . 5 years of age , cattle aged 3 and 4 years had higher concentration of HCB but the concentration difference was not clear at age 5 .
 Chemical: HCB
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: HCB