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Biodegradation in water: screening tests

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Description of key information

Readily biodegradable: 70% in 28 days (OECD 301F); read across

Key value for chemical safety assessment

Additional information

Experimental data investigating the biodegradability of Fatty acids, C18-unsatd., dimers, reaction products with fatty acids, C14-18 and C16-18-unsatd. and propylidynemethanol (CAS 162353-70-0) are not available. The assessment was therefore based on studies conducted with the structural analogue substances C18 Fatty acid, dimers, mixed ester with oleic acid and trimethylolpropane (CAS 147256-33-5) and Fatty acids, C16-18 and C18-unsatd., triesters with trimethylolpropane (CAS 68002-78-8) as part of a read across approach, which is in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. Further justification is given within the overall summary chapter 5.1 and within the analogue justification section 13.

The biodegradability of C18 Fatty acid, dimers, mixed ester with oleic acid and trimethylolpropane (CAS 147256-33-5) was tested according to OECD guideline 301F (Henkel KGaA, 2000). Non-adapted effluent obtained from a STP predominately treating domestic sewage was used as inoculum. Based on the O2 consumption a mean degradation rate of 70% was observed after 28 days. The degradation rate did not reach the pass level of 60% within the 10-day window. The test substance is a mixture of constituents with different chain-lengths, sequential (instead of concurrent). According to Annex I to the OECD Guideline for The Testing of Chemicals 'Revised introduction to the OECD guidelines for testing of chemicals, section 3' (OECD, March 2006), the 10 -day-window should not be considered for the test substance. Due to a degradation of > 60% within 28 days the test substance can be regarded as readily biodegradable.

A comparable result was determined in a study on the structural analogonFatty acids, C16-18 and C18-unsatd., triesters with trimethylolpropane (CAS 68002-78-8). The study was conducted according to OECD guideline 301 B ( BfB Laboratoire d'Analyses de Fluides, 2012). The substance was incubated under aerobic conditions with domestic activated sludge for 28 days. Based on the CO2 production of the inoculum a degradation rate of 86.6% was determined at test termination.

Based on the reliable experimental results from suitable read-across substances (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) C18 Fatty acid, dimers, mixed ester with oleic acid and trimethylolpropane (CAS 147256-33-5) is considered readily biodegradable according to the OECD criteria.

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