26238
For hazard assessment of multiwalled carbon nanotubes ( MWCNTs ) , a 90 - day inhalation toxicity study has been performed with Nanocyl NC 7000 in accordance with OECD 413 test guideline .
 carbon
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 carbon