4751
In contrast to other chewing habits ( betel , tobacco and khat ) , consumption of coca leaves does not induce genetic instability in cells from the oral cavity and our findings indicate that no adverse health effects take place in chewers which are associated with DNA damage .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 None