Application of in vitro mammalian cell micronucleus test and mammalian cell gene mutation test in genetic toxicity detection of hair dyes: a comparison study

  Objective  To determine genetic toxicity of three market-available hair dyes with in vitro micronucleus test (MNvit) and thymidinekinase mouse lymphoma assay (TK MLA) and to compare detection results of the two methods.

  Methods  Mouse L5178Y cell line was used in the detections. In MNvit test, micronucleus rate was calculated by microscopic counting of the specimens after smearing and staining. In MLA, mutation frequency (MF) was calculated for the determination of genetic toxicity.

  Results  Significant differences in micronucleus rate were observed between experiment group and negative control group for all the 3 hair dyes in MNvit (P < 0.05 for all), indicating that all the 3 hair dyes are genetic toxicity positive. The MF of the experimental groups were significantly higher than that of the control group for all the 3 hair dyes in TK MLA (all P < 0.05). The sample of No. 3 hair dye was genetic toxicity positive in MNvit test only under the absence of S₉ activation system.

  Conclusion  The genetic toxicity results of in vitro micronucleus test and TK gene mutation test are highly consistent for the 3 hair dyes detected. Due to TK gene mutation test being time and cost consuming and complicated in operation, micronucleus test in vitro can be considered as another genetic toxicity test. However, further studies are needed for combined genetic toxicity test because of the inconsistency between the genetic toxicity results of in vivo and in vitro micronucleus test.