Mixture genotoxicity of 2,4-dichlorophenoxyacetic acid, acrylamide, and maleic hydrazide on human Caco-2 cells assessed with comet assay.

Assessment of genotoxic properties of chemicals is mainly conducted only for single chemicals, without taking mixture genotoxic effects into consideration. The current study assessed mixture effects of the three known genotoxic chemicals, 2,4-dichlorophenoxyacetic acid (2,4-D), acrylamide (AA), and maleic hydrazide (MH), in an experiment with a fixed ratio design setup. The genotoxic effects were assessed with the single-cell gel electrophoresis assay (comet assay) for both single chemicals and the ternary mixture. The concentration ranges used were 0-1.4, 0-20, and 0-37.7 mM for 2,4-D, AA, and MH, respectively. Mixture toxicity was tested with a fixed ratio design at a 10:23:77% ratio for 2.4-D:AA:MH. Results indicated that the three chemicals yielded a synergistic mixture effect. It is not clear which mechanisms are responsible for this interaction. A few possible interactions are discussed, but further investigations including in vivo studies are needed to clarify how important these more-than-additive effects are for risk assessment.