The effects of 4CMB, 4HMB and BC on SCE, chromosome aberration and point mutation in cultured Chinese hamster ovary cells.

Cultured Chinese hamster ovary cells (CHO-KI-BH4) were treated for 2 h with 4CMB, 4HMB and BC, in the absence of any exogenous metabolic activation system. The cells were subjected to tests for survival, sister-chromatid exchange, chromosome aberration and mutation to thioguanine resistance. 4HMB had no effect in any test at concentrations up to 100 microgram/ml. 4CMB was slightly more toxic than BC. Both 4CMB and BC induced SCE and chromosome aberrations, but the effects were more marked with BC. With 4CMB, SCE increased with dose only up to about 7 microgram/ml and then levelled off. A weak mutagenic effect was observed with both BC and 4CMB, but in each case, the response reached a peak and was not evident at higher doses.