15328
It is suggested that synergistic DNA damage induced by simultaneously exposure of hexavalent chromium and nickel compounds is possibly related to oxidative stress .
 Chemical: hexavalent chromium; Chemical: nickel
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: hexavalent chromium; Chemical: nickel