In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: The renal failure usually develops about 8 - 10 mth after start of mitomycin C treatment and the mortality is approximately 60 % from renal failure or pulmonary edema .
### Output Text:
The renal failure usually develops about 8 - 10 mth after start of <span class="chemical">mitomycin C</span> treatment and the mortality is approximately 60 % from renal failure or pulmonary edema . 