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: The negative effects of Bisphenol A ( BPA ) on neurodevelopment and behaviors have been well established .
### Output Text:
The negative effects of <span class="chemical">Bisphenol A</span> ( <span class="chemical">BPA</span> ) on neurodevelopment and behaviors have been well established . 