The in vitro mammalian chromosome aberration test.

The short-term in vitro mammalian cell chromosome aberration test is used to assess potential genotoxic hazard of test substances. Mammalian cells are cultured in vitro, exposed to a test substance, harvested, and the frequency of asymmetrical structural chromosome aberrations is measured. Human peripheral blood lymphocytes do not normally divide. The assessment of the effects of cyclophosphamide on lymphocytes, stimulated to divide in whole blood cultures in vitro, is described. Procedures that are important in generating accurate results are emphasised, to avoid false positive results. The study design for a regulatory assay, the use of established cell lines, alternative methods of measuring cytotoxicity and analysis of results are included.