20171
There have been many suggestions of a ZnO - np toxicity paradigm but the underlying molecular mechanisms about the toxicity of ZnO - np remain unclear .
 Chemical: ZnO; Chemical: ZnO
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: ZnO; Chemical: ZnO