Position paper on the classification of Hydroquinone (HQ) in the European Union (EU) as a mutagen and/or carcinogen

The conclusions stated after evaluation of 49 test results are presented in Table 1 for the in vivo mutagenicity and in Table 2 for in vitro mutagenicity. To evaluate the mutagenicity of the product, the criteria in point 4.2.2 of the Annex VI to the Directive 67/548/EEC are used. The tests using intra-peritoneal administration are not taken into account to determine the mutagenicity of hydroquinone. This route of exposure is used experimentally to induce more severe results where more relevant routes do not provide sufficiently extreme exposure conditions. Moreover, the intra-peritoneal route is not considered as relevant as this way of exposure is very unlikely to occur in humans.