The genotoxicity of iron and chromium in electroplating effluents

Electroplating effluents were tested for their genotoxicity with the micronucleus test on newt larvae. The metallic content of the tested samples was responsible for the induction of micronuclei in red blood cells (RBC). Then, iron (Fe³⁺), chromium (Cr³⁺, Cr⁶⁺) and zinc (Zn²⁺) which were identified in these samples, were tested either separately or combined, at their concentrations in the electroplating effluents. Fe³⁺ induced a high level of micronuclei at 12.5 and 25 mg/l (nominal concentrations). Both soluble and non-soluble forms of iron were responsible for these genotoxic effects. At lower concentrations (0.6 and 4.5 mg/l) Fe³⁺ was not systematically genotoxic. Zinc could not be considered genotoxic on newt. Cr³⁺ gave negative responses, but exposure to Cr⁶⁺ (1 mg/l) could result in a significant number of micronucleated RBC in some cases. The most dramatic genotoxic effects were registered when Fe³⁺ and Cr⁶⁺ were combined. This study demonstrates that interactions between pollutants and the effects of non-soluble chemicals on aquatic vertebrates and invertebrates can no longer be neglected.