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 evaluate a test protocol for the performance of the in vitro micronucleus (MN) test using the V79 cell line with one treatment and one sampling time only. A total of 26 coded substances were tested in this study for MN-inducing properties. Three substances were tested by all 10 laboratories and 23 substances were tested by three or four laboratories in parallel. Six aneugenic, 7 clastogenic and 6 non-genotoxic chemicals were uniformly recognised as such by all laboratories. Three chemicals were tested uniformly negative by three laboratories although also clastogenic properties have been reported for these substances. Another set of three clastogenic substances showed inconsistent results and one non-clastogenic substance was found to be positive by one out of three laboratories. Within the study, the applicability of the determination of a proliferation index (PI) as an internal cytotoxicity parameter in comparison with the determination of the mitotic index (MI) was also evaluated. Both parameters were found to be useful for the interpretation of the MN test result with regard to the control of cell cycle kinetics and the mode of action for MN induction. The MN test in vitro was found to be easy to perform and its results were mainly in accordance with results from chromosomal aberration tests in vitro.

The influence of ethanol treatment of cytogenetic effects in bone marrow cells of Chinese hamsters by cyclophosphamide, aflatoxin B1 and patulin.

Chromosomes were investigated from the bone marrow of Chinese hamsters which received 10% (v/v) ethanol as the only liquid supply for a period of 9 weeks. At the end of the ethanol drinking period 1 group of animals received 2 oral doses of 80 mg/kg cyclophosphamide (CP), a second group received 2 oral doses of 25 mg/kg aflatoxin B1 (AFB1), a third group 2 oral doses of 20 mg/kg patulin (PA). The 2 applications were separated by 24 h. The intake of ethanol had no effect on the bone marrow chromosomes, and had no potentiating effect on CP induced aberrations. 9 weeks consumption of 10% (v/v) ethanol revealed likewise no influence on the frequencies of chromosomal aberrations induced by the indirect mutagen AFB1. However, the rate of chromosomal aberrations induced by the direct mutagen PA was clearly suppressed in ethanol drinking animals.