Hexamethylentetramin
MAK-Begründung, Nachtrag
Andrea Hartwig1 (Vorsitz der Ständigen Senatskommission zur Prüfung gesundheitsschädlicher Arbeitsstoffe, Deutsche Forschungsgemeinschaft)MAK Commission2
1 Institut für Angewandte Biowissenschaften, Abteilung Lebensmittelchemie und Toxikologie, Karlsruher Institut für Technologie (KIT), Adenauerring 20a, Geb. 50.41, 76131 Karlsruhe, Deutschland
2 Ständige Senatskommission zur Prüfung gesundheitsschädlicher Arbeitsstoffe, Deutsche Forschungsgemeinschaft, Kennedyallee 40, 53175 Bonn, Deutschland
Abstract
The German Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area (MAK Commission) summarized and re-evaluated the data for hexamethylenetetramine [100-97-0] to derive an occupational exposure limit value (maximum concentration at the workplace, MAK value) considering all toxicological end points. Relevant studies were identified from a literature search. Clinical findings demonstrate that frequent or regular contact with hexamethylenetetramine can lead to skin sensitization. This was confirmed by a study in animals. Therefore, the “Sh” designation has been retained. There are no data for respiratory sensitization. Hexamethylenetetramine releases formaldehyde in aqueous solution only in very small amounts at physiological pH levels. Therefore, a carcinogenic effect on the nasal mucosa epithelium, as with formaldehyde, is not expected. It is unlikely that the formaldehyde released from hexamethylenetetramine reaches the germ cells in active form. Oral administration in rats and mice of up to 2 g/kg body weight (bw) for up to 104 weeks did not result in systemic toxicity. The histopathological examination of male and female rats did not reveal any effects after administration of a hexamethylenetetramine dose of 50 mg/kg bw in the drinking water for 50 weeks. This NOAEL was used to derive a MAK value of 20 mg/m3 for the inhalable fraction of hexamethylenetetramine. As the critical effect is systemic, Peak Limitation Category II has been set with an excursion factor 8. There are no reliable data for prenatal developmental toxicity and hexamethylenetetramine has therefore been assigned to Pregnancy Risk Group D. Skin contact is not expected to contribute significantly to systemic toxicity.
