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Environmental fate & pathways

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Fatty acids, C16-18 and C18-unsatd., hexaesters with dipentaerythritol (CAS 68604-38-6) is characterised by a low water solubility (<0.15 mg/L; Frischmann, 2012), a low vapour pressure (VP < 0.00001 Pa, SPARC (v4.6)) and a high log Koc indicating a high adsorption potential (log Koc 27.6 - 30.72 MCI method, KOCWIN v2.00). The substance is not readily biodegradable (7.6% (CO2 evolution) after 28 d). Nevertheless, an extensive elimination of the substance in sewage treatment plants is expected. According to the Guidance on information requirements and chemical safety assessment, Chapter R.7b (ECHA, 2012) once insoluble chemicals enter a standard STP, they will be extensively removed in the primary settling tank and fat trap and thus, only limited amounts will get in contact with activated sludge organisms. Due to the high adsorption potential of the substance (log Koc of 27.6 and 30.7 for the main components of the substance; Blum, 2011) a removal from the water column to a significant degree by adsorption to sewage sludge can be expected (Guidance on information requirements and chemical safety assessment, Chapter R.7b, (ECHA, 2012). Therefore, the concentration of the substance in conventional STP effluents is presumably negligible. However, when released to the environment a partition from the water phase to soil and sediment is predictable. Abiotic degradation is considered as not relevant for the substance. Hydrolysis is not expected due to the low water solubility. In addition, calculations using HYDROWIN v2.00 predict half-lives > 1 year for the main components of the substance (Blum, 2011). Furthermore the substance is not volatile (VP < 0.0001 Pa) and thus evaporation to the air and the transport through the atmospheric compartment is not likely. Accumulation in air and the subsequent transport to other environmental compartments is not anticipated. However, if released into air, the substance is susceptible to indirect photodegradation in air by OH-radicals since half-lives of less than 24 hours were calculated for the main components of the substance (Blum, 2011). The bioavailability of Fatty acids, C16-18 and C18-unsatd., hexaesters with dipentaerythritol (CAS 68604-38-6) is expected to be low due to the predicted environmental fate and high molecular weight of the substance components (MW: 1684 – 1853 g/mol).

Due to the low water solubility and metabolisation via enzymatic hydrolysis of the substance a relevant uptake and bioaccumulation in aquatic organisms is not expected. The part of Fatty acids, C16-18 and C18-unsatd., hexaesters with dipentaerythritol that have become systemically available, might be hydrolysed and the cleavage products can be further metabolized. However, due to its high molecular weight, absorption of Fatty acids, C16-18 and C18-unsatd., hexaesters with dipentaerythritol is not likely and thus, no extensive metabolism is expected but rather direct elimination. In conclusion, a bioaccumulation or biomagnification through the food chain of the substance is not expected.
This is supported by a low calculated BCF value of 0.89 L/kg ww (BCFBAF v3.01, Arnot-Gobas, including biotransformation, upper trophic).
Please refer to IUCLID Section 5.3 for a detailed overview on bioaccumulation of Fatty acids, C16-18 and C18-unsatd., hexaesters with dipentaerythritol (CAS 68604-38-6).

A detailed reference list is provided in the technical dossier (see IUCLID, section 13) and within CSR.