In vitro micronucleus assay with Chinese hamster V79 cells - Results of a collaborative study with in situ exposure to 26 chemical substances

A collaborative study with 10 participating laboratories was conducted to e valuate a test protocol for the performance of the in vitro micronucleus (M N) test using the V79 cell Line with one treatment and one sampling time on ly. A total of 26 coded substances were tested in this study for MN-inducin g properties, Three substances were tested by all 10 laboratories and 23 su bstances were tested by three or four laboratories in parallel. Six aneugen ic, 7 clastogenic and 6 non-genotoxic chemicals were uniformly recognised a s such by all laboratories. Three chemicals were tested uniformly negative by three laboratories although also clastogenic properties have been report ed for these substances. Another set of three clastogenic substances showed inconsistent results and one non-clastogenic substance was found to be pos itive by one out of three laboratories. Within the study, the applicability of the determination of a proliferation index (PI) as an internal cytotoxi city parameter in comparison with the determination of the mitotic index (M I) was also evaluated. Both parameters were found to be useful for the inte rpretation of the MN test result with regard to the control of cell cycle k inetics and the mode of action for MN induction. The MN test in vitro was f ound to be easy to perform and its results were mainly in accordance with r esults from chromosomal aberration tests in vitro. (C) 2000 Elsevier Scienc e B.V. All rights reserved.