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 most common symptomatic adverse reactions were tremor or ataxia ( 35 % ) , nausea and anorexia ( 8 % ) , visual halos or blurring ( 6 % ) , thyroid function abnormalities ( 6 % ) and pulmonary interstitial infiltrates ( 5 % ) .
### Output Text:
The most common symptomatic adverse reactions were tremor or ataxia ( 35 % ) , nausea and anorexia ( 8 % ) , visual halos or blurring ( 6 % ) , thyroid function abnormalities ( 6 % ) and pulmonary interstitial infiltrates ( 5 % ) . 