In Vitro Genotoxicity Assessment of m-Phenylenediamine Using the Micronucleus Test in Mammalian Bone Marrow Cells

On February 21, 2023, the Ministry of Food and Drug Safety prohibited five hair dye ingredients, including m-phenylenediamine, from use as ingredients in cosmetics based on an assessment that found these ingredients to pose genotoxicity risks, potentially causing genetic damage or mutations in humans. From August 22, 2023, six months after the date of regulatory amendment, the manufacture and import of products containing these ingredients have been banned. The Ministry of Food and Drug Safety has periodically reviewed the safety of 352 restricted-use ingredients, including preservatives, hair dyes, and UV filters, every five years through regular risk assessments. However, products already manufactured or imported prior to this regulation can be sold until August 21, 2025. In this context, a micronucleus test using mammalian bone marrow cells was conducted to determine the presence or absence of genotoxicity in m-phenylenediamine, which has been confirmed to exhibit genotoxicity. The micronucleus test using mammalian bone marrow cells was conducted in accordance with OECD TG 474. To evaluate the genotoxicity of the test substance, ICR mouse bone marrow cells were used to examine whether the test substance induced micronuclei. Genotoxicity testing requires evaluation based on a three-battery approach, comprising three different types of tests rather than a single test. Although the test substance showed a positive result in the reverse mutation test, an additional micronucleus test was conducted in this study to compare the results. The findings indicated a negative result for m-phenylenediamine in the micronucleus test, thereby supporting the necessity of the three-battery approach.