Studies on cigarette smoking related polycyclic aromatic hydrocarbon-DNA adducts in blood have produced conflicting results. To determine whether a subset of specific white blood cells is a useful marker for monitoring exposure to cigarette smoke, blood was obtained from 63 heavy smokers and 27 non-smokers. Adduct levels were determined by competitive enzyme-linked immunosorbent assay with a polyclonal antiserum recognizing benzo[a]pyrene and structurally related diolepoxide-DNA adducts. Analysis of the lymphocyte plus monocyte fraction from smokers indicated 70% had detectable adducts with a mean of 4.38 +/- 4.29 adducts/10(8) nucleotides, while in non-smokers the corresponding values were 22% and 1.35 +/- 0.78/10(8) (P < 0.001). Plasma cotinine levels differed significantly in smokers (286 +/- 90 micrograms/l) compared to non-smokers (4.4 +/- 3.3 micrograms/l) (P < 0.001). However, cotinine was not correlated with self-reported smoking history in these heavy smokers. Nor were DNA adducts in smokers correlated with cigarettes per day, pack-years and plasma cotinine, indicating large interindividual variation in DNA adduct formation. These data demonstrate lymphocytes plus monocytes from smokers have elevated levels of polycyclic aromatic hydrocarbon diolepoxide-DNA adduct levels compared to non-smokers.