Has developed a highly sensitive cost-effective method of DNA damage detection using flow cytometry. This method is more versatile than the fluorescence in-situ hybridization assay and the micronucleus test. In humans, samples of white blood cells can be separated by cell type and each cell type assayed for DNA damage. In other mammals, the general white cell population is assessed. In non-mammalian vertebrates, whole blood is examined, since the red cells are nucleated.