Application of the in vivo Pig-a gene mutation assay to test the potential genotoxicity of p-phenylenediamine

Abstract Currently, it remains controversial whether p -phenylenediamine (PPD) is genotoxic. In this study, we evaluated the potential genotoxicity of PPD using the newly-developed Pig-a gene mutation assay. The results of three classical genetic toxicity tests (bacterial reverse mutation assay, mammalian cell chromosomal aberration test, and mammalian erythrocyte micronucleus test) are all positive, suggesting that PPD is potentially genotoxic. In Pig-a assay, Sprague-Dawley rats are orally administered with PPD for 28 consecutive days at three doses (12.5, 25, and 50 mg/kg/day). Our result shows that PPD (25 and 50 mg/kg/day) dose-dependently increases RET CD59− value over controls on Day 8. RET CD59− keeps increasing to the maximum on Day 15 and then decreases until Day 29. PPD also dose-dependently increase RBC CD59− value on Day 15, which keeps elevating until Day 29. The time-course of RET CD59− and RBC CD59− induced by PPD are similar with that induced by N-ethyl-N-nitrosourea (ENU) treatment for 3 days. Our data suggests that PPD has potential genotoxic effects, and the Pig-a assay is sensitive to assess mutagenicity. However, further investigation of the changes of RET CD59− and RBC CD59− induced by hair dyes containing PPD should be detected by Pig-a assay in occupational exposure population to confirm the safety of PPD usage.