1,2,4-Benzenetricarboxylic acid, tri-C9-11-alkyl esters

Endpoint summary

Additional information

Partitioning of substances into different environmental compartments depends mainly on their physico-chemical properties. Based on experimental studies all members of the Polyfunctional Fatty acid Ester (PFAE) aromatic category can be considered as not readily biodegradable according to OECD criteria (20.7 - 45% biodegradation after 28 days). However, based on these biodegradation studies the category members can be considered as enhanced ultimately biodegradable (71.4 - 78% biodegradation in 40 - 50 days). Therefore, the PFAE aromatic category members will not be persistent in the environment. The degradation via abiotic hydrolysis is not considered to be a relevant degradation pathway in the environment since QSAR results using HYDROWIN v2.00 resulted in half-lives (DT50) of >1 yr at pH 7. Considering the low water solubility (< 0.05 mg/L) and the high potential for adsorption to organic soil and sediment particles (log Koc: > 5, MCI method, KOCWIN v2.00), the main target compartments for the PFAE aromatic category members would be soil and sediment. However, the substances are enhanced ultimately biodegradable and highly sorptive, based on calculated estimation, and are thus expected to be eliminated and adsorbed to sewage sludge in sewage treatment plants to a high extent. Release to surface waters, and thereby exposure of sediment is therefore very unlikely. Evaporation into air and the transport through the atmospheric compartment is not expected since the category members are not volatile based on the low vapour pressure values (VP: < 0.001 Pa). Accumulation in air and the subsequent transport to other environmental compartments is thus not anticipated. However, if released into air, all category members are susceptible to indirect photodegradation by reaction with OH-radicals with a DT50: < 24 h (AOPWIN v1.93). Due to the low water solubility, complete environmental biodegradation in a short time period and low absorption potential in biota due to the high molecular weight of the substances (which significantly reduces the absorption due to steric hindrance to cross biological membranes of the PFAE aromatic category members), a relevant uptake and bioaccumulation in aquatic organisms is not expected. Furthermore, absorbed molecules of the category members will be metabolized and the metabolites will be excreted. This is supported by low BCF values calculated for all category members (BCF 0.89 L/kg; BCFBAF v3.01; Arnot-Gobas, including biotransformation, upper trophic).

Please consider that the originally proposed category approach addressing all Polyfunctional acid esters (PFAE) aromatic is currently under revision and will finally result in an analogue approach for the registration. Therefore, two documents, the category justification and explanatory notes for the analogue approach are provided in Section 13.