DISCUSSION PAPER: QUANTITATIVE ASPECTS OF USING DNA REPAIR TO DETECT MUTAGENS AND CARCINOGENS

The observation that mammalian cells can repair damage to their DNA by chemical carcinogens and mutagens has prompted much research on the role of DNA repair mechanisms in mutagenesis and carcinogenesis. Several investigators have suggested that DNA repair might be exploitable as a screening procedure for evaluating unknown chemicals for mutagenic and carcinogenic potential. Although some recent papers have dealt with DNA repair elicited either by direct acting carcinogens or by precarcinogens treated with suitable metabolic activation systems, relatively little information is available on the quantitative aspects of detection. This communication stresses 3 aspects of this problem: the relation between the amount of DNA damage and repair synthesis, a comparison of DNA repair and mammalian specific locus tests for detecting mutagens and carcinogens, and the critical role of activation in any widely used test procedure.