Toxicity of metal-ethylenediaminetetraacetic acid solution as a function of chemical speciation: an approach for toxicity assessment.

The influence of complexation by ethylenediaminetetraacetic acid (EDTA) on the toxicity of Cd(II), Cu(II), Cd(II), and Ni(II) was investigated. Result of the Microtox test, which is based on measuring the decrease of light emitted by Vibrio fischeri bacterium when exposed to a toxicant, was used as an indication of toxicity. The effect of pH and EDTA molar ratio that might potentially modify the percentage of chemical species in solution on toxicity was evaluated.