This project focuses on the investigation of chemical carcinogenesis by polycyclic aromatic hydrocarbons. The carcinogenic properties of these environmental pollutants are mediated by diol epoxide metabolites that modify the amino groups on the DNA bases. We study the chemistry of the reaction of these metabolites with nucleic acid components and we study the consequences of these reactions by examining the mutagenicity of selected polycyclic aromatic hydrocarbon-DNA adducts in Escherichia coli when the adducts are incorporated in plasmid vectors.