Registration Dossier

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

There is only limited data available on the environmental fate of Hexanedioic acid, di-C16-18 alkyl esters (CAS 92969-90-9). Therefore, additional QSAR calculations were conducted to fulfill the standard information requirements laid down in Annex VIII, 1.5, of the REACh Regulation (EC) No. 1907/2006.

Hexanedioic acid, di-C16-18 alkyl esters (CAS 92969-90-9) is characterised by a low water solubility (<0.05 mg/L), high low Pow (log Pow >7.7) and a high adsorption potential (log Koc >5). The substance is considered readily biodegradable according to OECD criteria. Thus, abiotic degradation by hydrolysis is not considered to be a relevant degradation pathway. According to the Guidance on information requirements and chemical safety assessment, Chapter R.7b, readily biodegradable substances can be expected to undergo rapid and ultimate degradation in most environments, including biological Sewage Treatment Plants (STPs) (ECHA, 2017). Due to ready biodegradability and high potential for adsorption, the substance can be effectively removed in conventional STPs by biodegradation and sorption to biomass. Furthermore, the Guidance also states that 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 come into contact with activated sludge microorganisms. As a consequence only negligible amounts of the substance are expected to be released into the environment through conventional STPs, if at all. Whatever fraction is released into the aquatic environment will undergo extensive biodegradation and will preferentially distribute into the sediment compartment through sorption to organic matter, leading to a rapid reduction of the bioavailability of the substance in water. Thus, the relevant route of uptake in aquatic organisms is expected to predominantly occur by ingestion of particle bound substance, but the bioavailability of the substance is presumably very low based on its physico-chemical properties.