Glaswolle, Halbwertszeit < 40 Tage (faserförmige und granuläre Bestandteile)
MAK-Begründung
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 evaluated the data for glass wool WHO fibres with a half-life in rats of less than 40 days after intratracheal administration (glass wool t1/2 < 40 d) to derive an occupational exposure limit value (maximum concentration at the workplace, MAK value) considering all toxicological end points. In the absence of inhalation studies for these glass wools, studies that investigated the more persistent glass wools, MMVF10 and MMVF11, are used. A two-year inhalation study in rats showed slight irritation in the lungs at 3.1 mg MMVF10/m3 and 4.8 mg MMVF11/m3, respectively. Two approaches were used to calculate the MAK value: the first applied assessment factors to account for the differences between rats and humans, resulting in a MAK value of 0.1 mg/m3 for the respirable fraction (R fraction) of glass wool t1/2 < 40 d. The second method calculated the human equivalent concentration, taking into account differences between rats and humans in terms of lifetime exposure, respiratory volume, clearance, lung surface and deposition fraction. The average human equivalent concentration from the two MMVF studies confirmed the MAK value of 0.1 mg/m3 R. The MAK value is valid for fibrous dusts and granular components formed from them. Peak Limitation Category II with an excursion factor 8 has been set. It can be assumed that carcinogenic effects induced by fibre toxicity will not occur if the MAK value is observed and glass wool t1/2 < 40 d has been classified in Carcinogen Category 4. MMVF10 was not mutagenic in the lungs of BigBlue rats after intratracheal instillation. Studies in germ cells are not available. In the absence of developmental toxicity studies, the substance has been assigned to Pregnancy Risk Group D. Dermal absorption is not expected to contribute significantly to systemic toxicity. There are no data for respiratory or skin sensitization.
