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: Associations between use of benzodiazepines or related drugs and health , physical abilities and cognitive function : a non - randomised clinical study in the elderly .
### Output Text:
Associations between use of <span class="chemical">benzodiazepines</span> or related drugs and health , physical abilities and cognitive function : a non - randomised clinical study in the elderly . 