16907
Twelve Pb doses ( 7 mu g Pb / 1 g BW ) were administered orally over a 5 - week period .
 Chemical: Pb; Chemical: Pb
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: Pb; Chemical: Pb