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: We used updated diazinon exposure and cancer incidence information to evaluate solid tumour risk in the AHS .
### Output Text:
We used updated <span class="chemical">diazinon</span> exposure and cancer incidence information to evaluate solid tumour risk in the AHS . 