Comparison of different cytotoxicity measurements for the in vitro micronucleus assay using L5178Y and TK6 cells in support of OECD draft Test Guideline 487

The reference genotoxic agents mitomycin C, cadmium chloride, 2-aminoanthracene, vinblastine sulphate and 5-fluorouracil were tested in the in vitro micronucleus assay, in mouse lymphoma L5178Y cells and in human lymphoblastoid cells TK6, without cytokinesis block. This was done in support of the toxicity measures recommended in the late 2007 version of the draft OECD Test Guideline 487 for the testing of chemicals.Relative Population Doubling and Relative Increase in Cell Counts, used for the selection of the highest concentrations to be evaluated for genotoxicity assessment, based on a 50 ± 5% cytotoxicity, both allowed to equally detect positive mitomycin C, cadmium chloride, 2-aminoanthracene, vinblastine sulphate and 5-fluorouracil on L5178Y and/or TK6 cells. Therefore, these parameters, recommended in the draft Test Guideline 487, are suitable to select the concentrations at the cytotoxicity required for genotoxicity assessment in the in vitro micronucleus assay without cytokinesis block.