Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Only limited data is available on the environmental fate ofFatty acids, C16 and C18-22 - unsatd., C16-18 and C18 unsatd. alkyl ester (CAS 90990-29-7). Therefore, read-across to the structurally related source substance docosyl docosanoate (CAS 17671-27-1) was conducted in accordance with Regulation (EC) N° 1907/2006 Annex XI, 1.5. The source substance is characterized by a similar fatty acid chain length (C18 - 20) as well as a similar alcohol component (C20 - 22) and is therefore considered a suitable representative for the assessment of the ready biodegradability of the target substance.Based on the high degree of similarity between the physico-chemical properties of the target and source substance, the target substance is expected to have a similar environmental fate profile. A detailed analogue approach justification is provided in IUCLID section 13 of the technical dossier.

  

Based on the available data, the target substance is characterized by low water solubility (< 0.05 mg/L at 20 °C, EU Method A. 6), a high estimated log Kow (Log Pow > 10, QSAR, Vega version 1.1.3 - three models: Meylan/Kowwin version 1.1.4, MLogP version 1.0.0, ALogP version 1.0.0) and low vapour pressure (<0.0001 Pa at 20 °C, QSAR, ARChem SPARC version 4.6). Experimental data from a suitable source substance indicates that the target substance is readily biodegradable (75.3% within 28 d, OECD 301 C). 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). 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 organisms. Nevertheless, in the case where contact occurs, substances with high log Koc values are expected to be removed from the water column to a significant degree by adsorption to sewage sludge (Guidance on information requirements and chemical safety assessment, Chapter R.7a, ECHA, 2017) and whatever remains will be extensively biodegraded due to ready biodegradability.

Therefore, only negligible concentrations of the substance are likely to be released (if at all) into the environment through conventional STPs and whatever fraction is released will be extensively biodegraded. Overall, the bioavailability of the substance in water is expected to be very low based on the physico-chemical properties.