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 : During a mean follow - up of 3 . 3 years , raloxifene was associated with an increased risk for venous thromboembolism ( relative risk [ RR ] 2 . 1 ; 95 % confidence interval [ CI ] 1 . 2 - 3 . 8 ) .
### Output Text:
RESULTS : During a mean follow - up of 3 . 3 years , <span class="chemical">raloxifene</span> was associated with an increased risk for venous thromboembolism ( relative risk [ RR ] 2 . 1 ; 95 % confidence interval [ CI ] 1 . 2 - 3 . 8 ) . 