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: OBJECTIVE : Diazinon , a common organophosphate insecticide with genotoxic properties , was previously associated with lung cancer in the Agricultural Health Study ( AHS ) cohort , but few other epidemiological studies have examined diazinon - associated cancer risk .
### Output Text:
OBJECTIVE : <span class="chemical">Diazinon</span> , a common <span class="chemical">organophosphate</span> insecticide with genotoxic properties , was previously associated with lung cancer in the Agricultural Health Study ( AHS ) cohort , but few other epidemiological studies have examined <span class="chemical">diazinon</span> - associated cancer risk . 