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: METHOD : Using five tagging SNPs ( rs6693503 , rs1805054 , rs4912138 , rs3790757 and rs9659997 ) , we conducted a genetic association analysis of case - control samples ( 197 METH - induced psychosis patients and 337 controls ) in the Japanese population .
### Output Text:
METHOD : Using five tagging SNPs ( rs6693503 , rs1805054 , rs4912138 , rs3790757 and rs9659997 ) , we conducted a genetic association analysis of case - control samples ( 197 <span class="chemical">METH</span> - induced psychosis patients and 337 controls ) in the Japanese population . 