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: Inorganic As exposure during key developmental periods is associated with a variety of adverse health effects including those that are evident in adulthood .
### Output Text:
<span class="chemical">Inorganic As</span> exposure during key developmental periods is associated with a variety of adverse health effects including those that are evident in adulthood . 