3628
In order to clarify the carcinogenic effects of coexposure to arsenic and iron , anchorage - independent growth and invasion in human untransformed HaCaT and transformed A431 keratinocytes were examined .
 Chemical: arsenic; Chemical: iron
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: arsenic; Chemical: iron