Evaluation of the combined toxicity of heavy metals and chlorpyrifos: A comparison of electrochemical and MTT methods

In the human living environment, heavy metals and chlorpyrifos can have harmful consequences due to their complex combination. In this study, binary, ternary, and quaternary combinations of three heavy metals and chlorpyrifos in different concentrations were evaluated for their combined toxic effects using an electrochemical method, and the MTT method was used to contrast the outcomes. The combined toxic effectiveness assessed by the electrochemical CI method revealed that, except for the binary combination of cadmium chloride and chlorpyrifos, which exhibited an antagonistic effect when mixed at an equal molar ratio, lead nitrate and chlorpyrifos showed an additive effect when combined, the quaternary combination exhibited a complex transition from synergistic to additive to antagonistic effects, the other mixtures showed consistent synergistic effects. When the ratio of heavy metals in the mixture was reduced, all of them displayed synergistic effects, except for the binary mixture of cadmium chloride and chlorpyrifos, which consistently maintained an antagonistic effect, and the ternary mixture of cadmium chloride, lead nitrate, and chlorpyrifos displayed additive effects. The complex toxicity mechanisms of the mixtures do not impact the response of cellular electrochemical signals coming from the intracellular purine bases on cytotoxicity. The electrochemical approach successfully captured the various combined toxic effects of the mixture, and the outcomes were consistent with the MTT method. This method is expected to emerge as a novel approach for detecting combined toxicity.