Fatty acids, C8-C18 (even numbered), decyl esters

Biodegradation in water: screening tests

Description of key information

Readily biodegradable: 67% (O2 consumption) after 28 d (OECD 301C)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Since no studies investigating the ready biodegradability of Fatty acids, coco, decyl esters (CAS 93455-79-9) are available, in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5 a read-across to the structurally related source substance Tetradecanoic acid, tetradecyl ester (CAS 3234-85-3) was conducted. The read-across substance is representative to evaluate the biodegradation of Fatty acids, coco, decyl esters (target substance). The target substance is a UVCB substance specified by mainly C12 linear fatty acids esterified with a linear alcohol of a chain length of C10. The source substance is a mono-constituent ester of a linear C14 fatty acid and a linear C14 alcohol. The potential for ready biodegradation is dependent on the chain lengths of the fatty acid and the alcohol. Therefore, a substance with longer chains of fatty acid and alcohol is considered reliable to assess the biodegradation of the target substance.In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substance was used for the assessment.This read-across is justified in detail in the overall summary (IUCLID Section 6.1) and within the analogue justification in IUCLID Section 13.
Moreover, the biodegradation of two representative constituents of the target substance (containing C12 and C14 fatty acids, respectively) was assessed using the VEGA v1.0.8 (Q)SAR model.
The study with the source substance tetradecyl myristate (CAS 3234-85-3) was performed according to OECD 301C (GLP) under aerobic conditions using a mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment as inoculum. The inoculum of 100 mg/L was degraded to 67% (BOD) after 28 d. Since the substance reached the pass level for OECD 301C (biodegradation is > 60% after 28 d, no 10-day window required) tetradecyl myristate is readily biodegradable according to the OECD criteria.
Supporting (Q)SAR predictions using VEGA v1.0.8 showed that the main components of the UVCB target substance are readily biodegradable. The prediction is valid and reliable. Similar molecules with experimental data were found within the training set showing that the substance is readily biodegradable. This result supports the experimental study with a structurally very similar source substance as discussed above.
Based on the results from one structurally related read-across substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) in combination with reliable (Q)SAR data for the target substance, it can be concluded that the target substance Fatty acids, coco, decyl esters is readily biodegradable according to the OECD criteria.