Evaluation of different cytotoxic and cytostatic measures for the in vitro micronucleus test (MNVit): Summary of results in the collaborative trial

This paper summarises the data for 14 different chemicals tested for induction of micronuclei (MN) in 5 different cell types across 12 different laboratories. All 14 chemicals induced biologically and statistically significant increases in MN frequency in the different cell types (L5178Y, TK6, CHO, CHL, V79) in the absence of cytochalasin B at or below target range toxicity (55 + 5%) irrespective of whether relative cell count (RCC), relative increase in cell count (RICC) or relative population doubling (RPD) was used as a measure of cytotoxicity/cytostasis to select the top concentration. All measures of cytotoxicity in the absence of cytochalasin B are therefore considered equally acceptable for use, and the responses were comparable to those obtained in the presence of cytochalasin B.