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 liver damage was characterized according to hepatocellular , cholestatic , and mixed laboratory criteria and to histologic criteria when available .
### Output Text:
The liver damage was characterized according to hepatocellular , cholestatic , and mixed laboratory criteria and to histologic criteria when available . 