18886
The exact relationship between the physical - chemical properties of carbon nanotubes , their cell to - cell interactions , reactivity , and biological / systemic consequences are relevant issues and it is important to know suchinter - relationships beforehand to employ the benefits of these nanomaterials without the hazardous consequences .
 Chemical: carbon
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: carbon