The intermediates then decompose to electrophilic methyl-,pyridyloxobutyl-, and pyridylhydroxybutyl-diazonium ions, which may attack DNA molecules, resulting in the formation of methyl DNA adducts and pyridyloxo(hydroxy)butyl DNA adducts. Under strong acidic condition, pyridyloxo(hydroxy)butyl DNA adducts hydrolyze to HPB or PBD.