7-Methyldeoxyguanosine as a marker of exposure to environmental methylating agents.

7-Methyldeoxyguanosine (7-medG) may be a useful marker of human exposure to methylating agents at the individual level. Methods of detection, including 32P-postlabeling, HPLC with electrochemical or fluorescence detection, and immunoassays, are critically summarized. These methods have been applied to the analysis of 7-medG in human samples, resulting from environmental exposure or endogenous processes. Detectable levels of adduct have been demonstrated in several tissues (liver, lung, bronchial, pancreas) and peripheral white blood cells. Studies are in progress to verify the possible use of white blood cells as a surrogate for internal organs.