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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Readily biodegradable: 75.3% (BOD) 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, C16-18, C16-18-alkyl esters (CAS 97404-33-6) 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 member docosyl docosanoate (CAS 17671-27-1) was conducted. The read across is justified as docosyl docosanoate is characterized by a longer fatty acid chain length (C22) and a longer fatty alcohol chain length (C22) than Fatty acids, C16-18, C16-18-alkyl esters. The longer carbon chain lengths represent a worst case approach since the chain length of the fatty alcohol and the fatty acid are important factors for the extend of biodegradation. Further justification is given within the endpoint summary 6.1 and within the category justification in section 13.

The 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 readily biodegradable according to the OECD criteria.

Based on the results from one structurally related read-across substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) it can be concluded that Fatty acids, C16-18, C16-18-alkyl esters is readily biodegradable according to the OECD criteria.