DNA adducts reflect the amount of a ▶ xenobiotic that covalently reacts with nucleic acid bases at the target site (biologically effective dose) or in surrogate tissues (▶Surrogate markers). DNA adducts are mechanistically more relevant to ▶ carcinogenesis than the internal dose of a carcinogen, since they take into account interindividual differences in metabolism and of DNA repair capacity (Fig. 1). Several hundred DNA adducts, many with miscoding properties, are known to be produced by some 20 classes of carcinogens and through endogenous oxidative processes. DNA adducts are used in human ▶ biomonitoring as dosimeters of early biological effects and predictors of cancer risk. These ▶ biomarkers also provide tools for studying disease pathogenesis, etiology, and for verifying preventive measures in human cancer. Characteristics