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: After further adjustment for potential confounders , the odds ratio in women who reported using cocaine and / or amphetamine was 7 . 0 ( 95 % confidence interval = 2 . 8 - 17 . 9 ) .
### Output Text:
After further adjustment for potential confounders , the odds ratio in women who reported using <span class="chemical">cocaine</span> and / or <span class="chemical">amphetamine</span> was 7 . 0 ( 95 % confidence interval = 2 . 8 - 17 . 9 ) . 