The purpose of this study is to assess mixtures of priority environmental pollutants for synergistic, addative or antagonistic interactions. The particular emphasis will be on inorganic interaction with organic pollutants. It is possible that metallo-organic complexes of appropriate staucture and charge can be formed in situ upon mixing of suitable ligands with transition series metal ions thereby producing genetically toxic stable complexes. The toxic and genotoxic effects will be assessed using microbial assay systems, the first being an E. coli microtiter DNA repair assay which assesses differential lethality. The second will be the Ames reversion assay for mutagenesis. Twenty inorganic elements and at least twenty priority organic pollutants will be tested individually in the repair assay. Any positives will be fully Ames tested. Then the forty will be placed in a twenty by twenty matrix for binary mixing and testing in the DNA repair assay. Each of the forty will also be mixed with each of five known carcinogens and the interactions tested on both the repair assay and the Ames test. Enzyme activation using three different enzyme sources will be tested in each case using a microtiter double dilution technique to estalixh optimum concentrations. The repair assay will give acute toxicity results in minimal inhibitory concentrations as well as DNA repair patterns. The Ames test will assess effects on frameshift and base pair substitution mutagenicity. This data should be invaluable in predicting possible interactions of complex environmental mixtures. A new series of cell surface defective, repair deficient strains of E. coli recently constructed in our laboratory make differential lethaliay testing of the larger and more complex organics possible.