Deoxyribonucleic acid (DNA) is the universal blueprint for life on Earth. DNA is the code of Life.The integrity of the genome is continuously challenged by both endogenous and exogenous DNA damaging agents.It has been estimated that in an average mammalian cell can have ten to a hundred thousand DNA lesions.DNA damage plays a major role in mutagenesis, carcinogenesis and ageing.A thorough knowledge of the types and prevalence of endogenous DNA damage is thus essential for an understanding of the interactions of endogenous processes with exogenous agents and the influence of damage of endogenous origin on the induction of cancer and other diseases.