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: PEG 400 impressively decreased both acute high - dose and chronic low - dose - ADR - associated lethality .
### Output Text:
<span class="chemical">PEG 400</span> impressively decreased both acute high - dose and chronic low - dose - <span class="chemical">ADR</span> - associated lethality . 