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: Chloroacetaldehyde and its contribution to urotoxicity during treatment with cyclophosphamide or ifosfamide .
### Output Text:
<span class="chemical">Chloroacetaldehyde</span> and its contribution to urotoxicity during treatment with <span class="chemical">cyclophosphamide</span> or <span class="chemical">ifosfamide</span> . 