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Since the mean ratio of arsenic and iron in well water was 1 : 10 in cancer - prone areas of Bangladesh , effects of 1 mu M arsenic and 10 mu M iron were investigated .
 Chemical: arsenic; Chemical: iron; 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; Chemical: arsenic; Chemical: iron