Isooctadecanoic acid, mixed esters with oxybis[propanediol]

Endpoint summary

Additional information

The target substance Isooctadecanoic acid, mixed esters with oxybis[propanediol] is characterised by low water solubility (< 0.15 mg/L at 20 °C, pH 6.5-6.6), low vapour pressure (<0.0001 Pa at 20 °C), a high estimated log Koc (3.05-19.2, KOCWIN v2.00) and a high estimated log Kow (log Pow > 10, KOWWIN v1.68). Abiotic degradation via hydrolysis is not considered relevant for the substance. Calculations using HYDROWIN v2.00 predict half-lives > 1 year for the substance at pH 7 and > 48 d at pH 8. Moreover, the substance is not volatile (VP < 0.0001 Pa at 20 °C) and thus evaporation to the air and subsequent transport through the atmosphere to other environmental compartments is not likely.The high molecular weight of the substance significantly reduces the absorption due to steric hindrance to cross biological membranes. Given a very high log Koa value of 14.55(KOAWIN v1.10), the substance will not partition to aerosols and predominantely occur in the hydrophobic compartement.

It can be concluded that the bioaccumulation potential of Isooctadecanoic acid, mixed esters with oxybis[propanediol] is negligible. BCF/BAF values estimated by QSAR (BCFBAF v3.01) also support this assumption (BCF values all well below 2000 L/kg).

Considering the low water solubility (< 0.15 mg/L) of the target substance and the considerable potential for adsorption to organic soil and sediment particles (log Koc > 10), the main compartments for environmental distribution are expected to be soil and sediment.

The target substance is considered not readily biodegradable based on read-across from similar substances. 

However, in the case insoluble chemicals enter a standard Sewage Treatment Plant (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, according to the Guidance on information requirements and chemical safety assessment, Chapter R.7b (ECHA, 2014). As a result of the high adsorption potential of the substance (3.05-19.2, KOCWIN v2.00) 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, 2014). In conclusion, the concentration of the substance in conventional STP effluents is presumably marginal.

QSAR calculations (HYDROWIN v2.00) were performed with the individual tri- and tetraester components of the target substance. Calculations indicate that hydrolysis is a negligible pathway for the fate of the substance in the environment. Estimated half-lives of > 1 year at pH 7 and > 48 d at pH 8 were calculated.

Based on the physico/chemical properties such as low water solubility and high potential for adsorption a reduced availability in water is expected. The high molecular weight (> 900 g/mol for Grade One and > 1200 g/mol for Grade Two) of the substance significantly reduces the absorption due to steric hindrance to cross biological membranes. It can be concluded that the bioaccumulation potential of Isooctadecanoic acid, mixed esters with oxybis[propanediol] is negligible.

The substance is not readily biodegradable based on read-across from the similar substance Isooctadecanoic acid, ester with oxybis[propanediol] (CAS 73296-86-3). Based on this analogue approach, the substance is expected to be not rapidly degradable by microorganisms in both the aquatic and terrestrial environments. As a result of the high adsorption potential of the substance, it is largely removed from the water column by adsorption to soil and sediment. The substance is therefore potentially persistent in soil and sediment.