Biomonitoring of exposure to 1,3-butadiene: detection by high-performance liquid chromatography and 32P-postlabelling of an adenine adduct formed by diepoxybutane.

1,2-Epoxy-3-butene and 1,2:3,4-diepoxybutane, the two oxidative metabolites of 1,3-butadiene, are considered to be involved in some of the carcinogenicity of the parent compound. Diepoxybutane is a bifunctional alkylating agent and reacts with DNA to form monoadducts and cross-links. We investigated DNA alkylation after exposure to diepoxybutane in order to develop a method for human biomonitoring. After reacting dAMP and then poly(dA-dT) (dA-dT) with diepoxybutane, we identified a major adenine adduct. Preliminary mass spectrometry indicated an adenine adducted by diepoxybutane at the N6 position. A high-performance liquid chromatography/32P-postlabelling method was developed, and the adduct was detected in calf thymus DNA and in DNA from Chinese hamster cells after exposure to diepoxybutane. The labelling efficiency, the amount of the adduct and its stability suggest that it could be a suitable indicator of exposure to butadiene.