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: Kidney cancer ( N = 94 ) risks were non - significantly elevated ( RRLT days = 1 . 77 ; 95 % CI 0 . 90 to 3 . 51 ; Ptrend = 0 . 09 ; RRIW days 1 . 37 ; 95 % CI 0 . 64 to 2 . 92 ; Ptrend = 0 . 50 ) , as were risks for aggressive prostate cancer ( N = 656 ) .
### Output Text:
Kidney cancer ( N = 94 ) risks were non - significantly elevated ( RRLT days = 1 . 77 ; 95 % CI 0 . 90 to 3 . 51 ; Ptrend = 0 . 09 ; RRIW days 1 . 37 ; 95 % CI 0 . 64 to 2 . 92 ; Ptrend = 0 . 50 ) , as were risks for aggressive prostate cancer ( N = 656 ) . 