8578
Therefore , the secondary effects caused by the combination of two NRTIs , mainly those related to amplification of genotoxic effects , due to increased risk of DNA damage caused by these drugs , should be carefully examined .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None