19640
In addition , research gaps and needs are identified to be able to optimize and validate the targeted THD in vitro test battery for a mechanism - based strategy for a decision to opt out or to proceed with further testing for THD .
 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