13526
Bladder is one of the major target organs of arsenic , and cyclooxygenase - 2 ( COX - 2 ) may play an important role in arsenic - induced bladder cancer .
 Chemical: arsenic; Chemical: arsenic
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: arsenic