In 2007, a working group of the German-speaking section of the
European Environmental Mutagen Society (GUM) recommended
[1] that Stage-1 in vitro genotoxicity testing should consist of
an Ames test plus an in vitro micronucleus test (MNvit), since
these tests cover all of the essential mutagenic endpoints (gene
mutations, structural chromosome damage, and aneuploidy), and
moreover cover testing in both prokaryotic and eukaryotic systems.
The MNvit has been retrospectively validated by ECVAM [2] and an
OECDguideline (TG487) hasnowbeen adopted [3]. The main difference
between the recommended two-test battery and other testing
approaches is the lack of a mammalian cell gene-mutation test,
most often the mouse-lymphoma assay (MLA). However, Pfuhler