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 incidence depends on dosage but not on the type of consumed nonionic CM , nor on the presence of cyanosis , and although CIN usually is reversible , more concern is needed for the prevention of such a complication in children .
### Output Text:
The incidence depends on dosage but not on the type of consumed nonionic <span class="chemical">CM</span> , nor on the presence of cyanosis , and although CIN usually is reversible , more concern is needed for the prevention of such a complication in children . 