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: However , three case control studies , one each in North Carolina , northern Maryland , and West Berlin , Germany , showed that habitual use of acetaminophen is also associated with chronic renal failure and ESRD , with a relative risk in the range of 2 to 4 .
### Output Text:
However , three case control studies , one each in North Carolina , northern Maryland , and West Berlin , Germany , showed that habitual use of <span class="chemical">acetaminophen</span> is also associated with chronic renal failure and ESRD , with a relative risk in the range of 2 to 4 . 