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: Smoking , nonsteroidal anti - inflammatory drug use , intravenous catheter site , dwell time of the needle , alcohol use , and pain during the injection had no effect on the incidence of venous complications .
### Output Text:
Smoking , nonsteroidal anti - inflammatory drug use , intravenous catheter site , dwell time of the needle , <span class="chemical">alcohol</span> use , and pain during the injection had no effect on the incidence of venous complications . 