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: This effect was modified by gender , with a greater risk in women versus men ( OR : 3 . 86 , 95 % CI : 1 . 70 to 8 . 75 vs . OR : 1 . 52 , 95 % CI : 0 . 80 to 2 . 89 ) .
### Output Text:
This effect was modified by gender , with a greater risk in women versus men ( OR : 3 . 86 , 95 % CI : 1 . 70 to 8 . 75 vs . OR : 1 . 52 , 95 % CI : 0 . 80 to 2 . 89 ) . 