Human cell line toxicity of binary and ternary chemical mixtures in comparison to individual toxic effects of their components.

Contaminated site projects involve health risk assessment procedures that must consider potential interactive effects of present contaminants. In order to establish a quick and reliable method that accounts for smaller than additive, additive, or greater than additive toxic effects, this study compared the cytotoxicity of 34 binary and ternary chemical mixtures of four structurally different chemicals to HeLa cells. Further, five blind samples of these mixtures or their components were tested to determine the ability to identify unknown mixtures. The colorimetric MTS in vitro cytotoxicity assay was used to detect cytotoxic effects after the cells were exposed for 1 h to serial dilutions of the mixtures. Experimental cytotoxicity data were compared and set against data predicted by a mathematical algorithm. They mainly showed additive effects of the components in mixture but also identified smaller than additive and greater than additive effects. A subjective classification scheme allowed evaluation of the toxicity of the blind samples in comparison to results from the study on binary and ternary mixtures tested before. This scheme focused on quantitative cytotoxicity data as well as on the slope of the concentration-effect curves and demonstrated the use of the MTS assay for human health risk assessments in the context of contaminated sites.