carcinogenic vs harmless

carcinogenic

adj
  • Causing or tending to cause cancer. 

noun
  • Synonym of carcinogen 

harmless

adj
  • Incapable of causing harm or danger; safe. 

  • Not intended to harm; inoffensive. 

How often have the words carcinogenic and harmless occurred in a corpus of books? (source: Google Ngram Viewer )