<protein> A toxin (poisonous substance) which harms the body by damaging DNA molecules, causing mutations, tumours, or neoplasms. ... (09 Oct 1997) ... 
Type: Term Pronunciation: gē-nō-tok′sin Definitions: 1. Any substance that damage DNA.
Genotoxin: A poisonous substance which damages DNA. A genotoxin can cause mutations in DNA (and so be a mutagen), it can trigger cancer (and so be a carcinogen), or it can cause a birth defect (and so be a teratogen). From geno- (genetic) + toxin (poison) = a genetic poison.