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: BACKGROUND : The possible role of alcohol in the development of hepatotoxicity associated with therapeutic doses of paracetamol ( acetaminophen ) is currently debated .
### Output Text:
BACKGROUND : The possible role of <span class="chemical">alcohol</span> in the development of hepatotoxicity associated with therapeutic doses of <span class="chemical">paracetamol</span> ( <span class="chemical">acetaminophen</span> ) is currently debated . 