An evaluation of caprolactam and benzoin in the mouse micronucleus test

Caprolactam (CAP) and benzoin (ZOIN) were tested in the mouse micronucleus test at two dose levels, one of which was the maximum tolerated dose. The compounds were administered by the oral route to groups of 5 male and 5 female mice. No statistical significant increase over control values of the frequency of PCE-containing micronuclei was observed at any dose level or sampling time, with the exception of CAP at a dose level of 700 mg/kg at the 24-h sampling time, where a small statistically significant effect was observed both when the sexes were analysed combined and separately. Due to this observation a limited repeat was carried out on CAP at the 700 mg/kg dose level at the 24-h sampling time. In the repeat study similar trends were observed even following the analysis of 5000 cells per animal. However, when these data were compared with historical control data no such effects were observed, the effects were therefore considered to be of questionable validity. Throughout the study the positive control (cyclophosphamide) gave an elevated biologically and statistically significant increase at all sampling times, thus verifying the sensitivity of the test system. It was therefore concluded that caprolactam and benzoin are not clastogenic in the mouse micronucleus test.