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: The clinical and radiographic features of amiodarone - induced pulmonary toxicity are characteristic but nonspecific .
### Output Text:
The clinical and radiographic features of <span class="chemical">amiodarone</span> - induced pulmonary toxicity are characteristic but nonspecific . 