Fig. 1

Comparison of RDLMN assay results of formalin-fixed method and collagenase digestion method using Group A chemicals. Incidences of MNHEPs (%); Comparison between formalin-fixed method (A) and collagenase digestion method reported by Hamada et al. [1] (B) in rats treated with Group A chemicals for 14 or 28 days. As for the 28-day RDLMN assay of NDPA using collagenase digestion method, it was conducted by Kissei Pharmaceutical Co., Ltd. as a collaborative study by CSGMT/JEMS MMS immediately after publication of a report by Hamada et al. [1]. Values are presented as the mean and SD. Differences in the incidences of MNHEPs between the test and vehicle control groups were analyzed by the Kastenbaum and Bowman test at significance levels of 5 and 1% (*: P < 0.05, **: P < 0.01). Differences in the incidences of mitotic phase cells between the test and vehicle control groups were analyzed by Dunnett’s multiple comparison test at significance levels of 5 and 1% (#: P < 0.05, ##: P < 0.01). Group A: genotoxic hepatocarcinogen