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EC number: 931-288-4 | CAS number: -
Endpoint summary
Administrative data
Link to relevant study record(s)
Description of key information
Key value for chemical safety assessment
Additional information
The following remarks on the toxicokinetics of HDI oligomer, uretdione type are based on physicochemical properties of the compound and on toxicological data. Experimental toxicokinetic studies were not performed.
HDI oligomers, uretdione type is a colourless, clear and viscous organic liquid under normal ambient conditions (Currenta, 2009). In water the substance is hydolytically unstable (cp. chapter "Water solubility"), therefore experimental data such as pH, pKa, log Pow cannot be obtained for the substance. HDI oligomers, uretdione type has a very low vapour pressure (2.90*10 E-04 Pa at 20 °C and 4.73*10 E-04 Pa at 25°C, Laus GmbH, 2010) and a dynamic viscosity of 196 mPa*s at 20 °C (Currenta, 2009), therefore inhalation exposure via vapour is not to be expected. Wherever aerosolization occurs exposure is possible.
There are no indications of systemic toxicity after inhalative exposure to the aerosol (report nos AT00075 (2002), AT03094 (2006), AT06241 (2010), all Bayer AG). All clinical signs and histopathological findings observed in these acute and repeated aerosol inhalation studies were related to the irritant properties of the substance. These effects most probably are related to the reactive nature of the isocyanate-groups of the substance. However, only very slight or slight irritation on eye and skin of rabbits were observed, respectively (OECD TG 405 and 404; both Bayer AG, 1982).
Regarding oral absorption at least partial hydrolysis is assumed to occur in the gastro-intestinal tract. Oral toxicity was low with an LD50 (rat) of > 5 ml/kg bw (corresponding to > 5665 mg/kg bw; Bayer AG, 1981). In this study no mortalities and no clinical signs at all were observed, therefore no indications for systemic availability can be concluded after oral exposure.
There are no dermal toxicity studies available for HDI oligomers, uretdione type, but due to its physico-chemical properties (hydrolysis; reaction of isocyanate-groups with nucleophilic groups e.g. -OH, -NH, -SH, cp. chapter “Stability in organic solvents and identity of relevant degradation products”) dermal absorption is assumed to be very low. The skin sensitizing properties of the substance (report no. 126326, Notox B.V., 1995) indicate that a dermal uptake, even though small, can occur.
The available in vivo-genotoxicity tests (MNT: report AT04888 (2008), UDS: AT05928/06058 (2010), all Bayer AG) indicate that DNA-reactive metabolites most probably will not be generated in mammalian organisms due to hepatic biotransformation.
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