There is growing evidence that carcinogens initiate the malignant process via specific alterations in DNA structure, i.e., the covalent binding of carcinogens to DNA bases. Thus, carcinogen-DNA adducts represent as markers for tumor initiation. Several new techniques have been reported for detecting exceptionally small quantities of adducts without requiring test chemicals to be radioactive. These methods are based on specific antibodies, fluorescence spectra, electrophore labeling, and 32P incorporation into DNA constituents. Recent developments have indicated that the (32)P labeling method is capable of measuring a wide spectra of unusually low levels .10 to the tenth power nucleotides of DNA adducts induced by a vast majority of known aromatic/hydrophobic environmental carcinogens (Gupta, 1985). The paper reviews the underlying principle of the approach, as well as some recent applications.