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: It has also been used for the management and prevention of cardiovascular disease , osteoporosis and dementia in older women but the evidence supporting its use for these indications is largely observational .
### Output Text:
It has also been used for the management and prevention of cardiovascular disease , osteoporosis and dementia in older women but the evidence supporting its use for these indications is largely observational . 