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: Blood pressure ( BP ) is more salt sensitive in men than in premenopausal women .
### Output Text:
Blood pressure ( BP ) is more <span class="chemical">salt</span> sensitive in men than in premenopausal women . 