Benzidine–DNA adduct levels in human peripheral white blood cells significantly correlate with levels in exfoliated urothelial cells

In a cross-sectional study of 33 workers exposed to benzidine and benzidine dyes and 15 non-exposed controls, we previously reported that exposure status and internal dose of benzidine metabolites were strongly correlated with the levels of specific benzidine–DNA adducts in exfoliated urothelial cells. We also evaluated DNA adduct levels in peripheral white blood cells (WBC) of a subset of 18 exposed workers and 7 controls selected to represent a wide range of adducts in exfoliated urothelial cells. Samples were coded and then DNA was analyzed using 32P-postlabeling, along with n-butanol extraction. One adduct, which co-chromatographed with a synthetic N-(3-phospho-deoxyguanosin-8-yl)- N′-acetylbenzidine standard, predominated in those samples with adducts present. The median level (range) of this adduct in WBC DNA was 194.4 (3.2–975) RAL×10 9 in exposed workers and 1.4 (0.1–6.4) in the control subjects ( p=0.0002, Wilcoxon Rank Sum Test). There was a striking correlation between WBC and exfoliated urothelial cell adduct levels (Pearson r=0.84, p