Methods will be developed and validated for quantifying human exposure to, and metabolism of, potent mutagens. We will focus on aminoimidazoazaarenes (AIA), chemical mutagens formed in meats by cooking and therefore widely consumed in the American diet. These chemicals are potent mutagens in the Ames/Salmonella assay and, where they have tested in long-term bioassays, are carcinogens. It is only in the past five years that these compounds have been isolated, identified, and synthesized in sufficient quantities for studies on their mechanisms of action. The next logical step in determining the human health risk posed by these chemicals requires quantification of their uptake, metabolism, and clearance rates in humans. In many ways the exposure to cooked-meat mutagens is prototypic of environment and occupational exposures to aromatic amines. There is chronic low level exposure to low doses of a complex mixture of chemicals. Individuals differ both in their exposures and in their ability to activate the compounds to potentially reactive electrophiles. Our studies will provide a comprehensive integration of several new methods for biochemical dosimetry. We already have monoclonal antibodies for the parent AIA compounds, and these cross react with some metabolites. We will incorporate these antibodies into immunoassays and validate the assays for the deletion of AIAs and AIA metabolites in human urine. An immunoassay to AIA-protein adducts will be developed and validated on adducted human serum proteins. Also, P32 post- labeling will be used to identify and quantify AIA-DNA adducts formed by humans. The markers developed under this project will permit studies on genetic and environmental influences on an individual's response to AIA exposure.
