18653
Cholinesterase activity was dose - dependently decreased in red blood cells at >= 4ppm and in the brain at 100ppm both in dams and offspring on PND 21 .
 None
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:  
Answer:
 None