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: Safety was assessed using adverse events , Extrapyramidal Symptom ( EPS ) rating scales , laboratory values , electrocardiograms , vital signs , and weight change .
### Output Text:
Safety was assessed using adverse events , Extrapyramidal Symptom ( EPS ) rating scales , laboratory values , electrocardiograms , vital signs , and weight change . 