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 : Since April 1994 to August 2004 , 461 out of 570 submitted cases , involving 505 drugs , were deemed to be related to DILI .
### Output Text:
RESULTS : Since April 1994 to August 2004 , 461 out of 570 submitted cases , involving 505 drugs , were deemed to be related to DILI . 