Blood protein conjugates and acetylation of aromatic amines. New findings on biological monitoring.

Internal stress of aromatic amines has so far been evaluated by their determination in blood or urine and by the degree of methemoglobin formation. Animal experiments have shown that these materials can form adducts and conjugates with proteins and nucleic acids. Our investigations show that these processes can also occur in human metabolism. For this the degree of such a formation of protein conjugates depends on an individually different potential for acetylation. In a positive sense it influences the magnitude and the rate of renal excretion of aminoaromates and their conjugates and metabolites formed by this metabolism. In contrast, only free nonacetylated aminoaromates can lead to the formation of conjugates with hemoglobin. These aminoaromates or their metabolites can then be detected quantitatively in intact erythrocytes during their lifespan. The degree of this protein conjugate formation correlates inversely with the magnitude of the acetylation potential depending on the availability of free non-acetylated aminoaromates. According to these results a clearer assessment of past stress or the presence of strain can be obtained with Biological Monitoring by a single determination of such hemoglobin adducts rather than by the traditional quantitative determination of aminoaromates or their metabolites in blood and/or urine or the methemoglobin concentration.