Isodecyl oleate

Biodegradation in water: screening tests

Description of key information

Readily biodegradable: 75.3% (BOD) after 28 d (OECD 301C)
Readily biodegradable: 68.1 - 71.7% (CO2 evolution) after 28 d (OECD 301B)
Readily biodegradable: 94.6% (CO2 evolution) after 28 d (OECD 301B)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Since no studies investigating the ready biodegradability of isodecyl oleate (CAS 59231-34-4) are available for this endpoint, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read across to the structurally related category members docosyl docosanoate (CAS 17671-27-1), 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) and 2-hexyldecyl oleate (CAS 94278-07-6) was conducted. The read-across substances are representative to evaluate the biodegradation of isodecyl oleate. Docosyl docosanoate is characterized by a longer fatty acid chain length (C22) and a longer fatty alcohol chain length (C22). This read-across substance can therefore be used for read-across as a worst case approach since the chain length of the fatty alcohol and the fatty acid are the determining factor for biodegradation. The branching of the alcohol component of isodecyl oleate is covered by the two read-across substances 2-octyldodecyl isooctadecanoate and 2-hexyldecyl oleate consisting of branched fatty alcohol components (2-octyldodecanol and 2-hexyldecanol) and similar fatty acid chain length (C18 iso and C18 unsatd.).

The first study with the read-across substance docosyl docosanoate 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 with a test substance concentration of 100 mg/L (Ministry of Economy, Trade and Industry, Japan, 1992). A biodegradation of 75.3% (BOD) was observed after 28 d. Since the substance reached the pass level for OECD 301C (biodegradation is > 60% after 28 d, no 10-day window required) docosyl docosanoate is stated to be readily biodegradable according to the OECD criteria.

The second study with the read-across substance 2-octyldodecyl isooctadecanoate was performed according to OECD 301B under GLP conditions (Desmares-Koopmans, 1998). Activated sludge was used as inoculum and the test substance was applied at a concentration of approx. 14.5 mg/L. A biodegradation of 68.1 - 71.7% was observed after 28 d of incubation under aerobic conditions. The substance reached the pass level of > 60% after 28 d and can be classified as readily biodegradable according to the OECD criteria. A 10-day window is not applicable for UVCB substances. Moreover, no inhibitory effects to activated sludge microorganisms were observed in the toxicity control (> 25% biodegradation after 14 d).

A third study with the read-across substance 2-hexyldecyl oleate showed that the substance (at a concentration of 10 - 20 mg/L based on DOC) is readily biodegradable according to the OECD criteria (biodegradation > 60% within 10-day window) (Bouillon, 2011). This study was performed according to OECD 301B (non-GLP) under aerobic conditions using domestic activated sludge as inoculum.

Based on the results from three structurally related read-across substances (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) it can be concluded that isodecyl oleate is readily biodegradable according to the OECD criteria.