3588
Using a self - made four - level prediction model to classify substances into four in vitro hazard categories , in vivo - in vitro concordance was mediocre , but could be improved by excluding substances causing pulmonary edema and emphysema in vivo .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 None