Xylidine isomers (2,3-xylidine, 2,5-xylidine, 3,4-xylidine, 3,5-xylidine)
MAK Value Documentation, supplement – Translation of the German version from 2020
Andrea Hartwig1 (Chair of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft)MAK Commission2
1 Institute of Applied Biosciences, Department of Food Chemistry and Toxicology, Karlsruhe Institute of Technology (KIT), Adenauerring 20a, Building 50.41, 76131 Karlsruhe, Germany
2 Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft, Kennedyallee 40, 53175 Bonn, Germany
Abstract
The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re-evaluated the xylidine isomers 2,3-, 2,5-, 3,4- and 3,5-xylidine [87-59-2, 95-78-3, 95-64-7, 108-69-0] considering all toxicological end points. The critical effects are methaemoglobinaemia, anaemia and effects on the spleen, liver and kidneys. A carcinogenicity study was performed with only 2,5-xylidine. Although the study is of limited validity, the angiosarcomas observed in male mice and fibromas and fibrosarcomas in rats are tumours typical for aromatic amines. Therefore, a carcinogenic potential is assumed and 2,3-, 2,5-, 3,4- and 3,5-xylidine are classified in Carcinogen Category 3 B for suspected carcinogens. All 4 isomers are genotoxic both in vitro with metabolic activation and in somatic cells in vivo. However, these findings are not quite consistent, this is typical for aromatic amines. Therefore, 2,3-, 2,5-, 3,4- and 3,5-xylidine are classified in Category 3 B for germ cell mutagenicity. A maximum concentration at the workplace (MAK value) is not derived because of the suspected mutagenicity. There are only limited data for percutaneous absorption, but as the systemic toxicity of these 4 isomers is high and they are suspected mutagens and carcinogens, the designation with “H” is retained. Studies of the sensitization potential are not available.
