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: RESULTS : Nine hundred one patients were randomized to treatment , 447 who received the lozenge and 454 who received the gum ( safety population ) .
### Output Text:
RESULTS : Nine hundred one patients were randomized to treatment , 447 who received the lozenge and 454 who received the gum ( safety population ) . 