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Environmental fate & pathways

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In an OECD 301B Ready Biodegradability: CO2 Evolution Test the substance only achieved 21% degradation over 28 days. This substance has a very low water solubility (<1.0 mg/L) which makes it a very difficult substance to test in a ready biodegradation study as the typical concentrations used in those studies exceed the solubility of the substance and reduce the bioavailability of the substance to the microorganisms.

A subsequent OECD309 (Aerobic Mineralisation in Surface Water - Simulation Biodegradation Test) study conducted with radiolabelled test substance at concentrations less than the solubility limit showed rapid primary degradation; a half- life of 4.5 days and approximately 95% degradation over 20 days providing strong evidence that the material is not persistent. The degradation products produced in the study could not be identified, due in part to the low test concentrations, which meant that analytical identification was not possible. As repeating the study at higher test concentrations is considered to be technically not feasible, due to the low solubility of the test item constituents, and the difficulties with labelling a complex UVCB substance, a QSAR modelling approach was conducted using EAWAG’s BBD Pathway Prediction System. This identified a number of initial degradation products, which match the initial degradation products produced from resin acids which make up the starting material in the manufacture of hydrogenated rosin alcohols. PACT assessments for the substances rosin and hydrogenated rosin which are composed of these resin acids concluded that these substances are not PBT or vPvB, and therefore the degradation products are not considered to be PBT.