3993
The current study investigated the effects of exposing male A / J mice to MS ( 6h / day , 5 days / week at 150 and 300 mg total particulate matter per cubic meter ) for 2 . 5 , 5 , 10 , and 18 months in selected combinations with postinhalation periods of 0 , 4 , 8 , and 13 months .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 None