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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Readily biodegradable: 76.5% in 28 days (OECD 301B, Modified Sturm Test)

Key value for chemical safety assessment

Additional information

No experimental data evaluating the potential for ready biodegradability of Glycerides,C14-18 and C16-18 unsaturated, mono-, di- and tri- (CAS No. 91052-28-7) are available. Therefore, a ready biodegradability study from a structurally related analogue substance, 1,2,3-propanetriyl trioleate (CAS No. 122-32-7) is used as read-across in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. Both substances are esters formed from the combination between fatty acids and glycerol as alcohol component. 1,2,3-propanetriyl trioleate is predominantly a triglyceride (the three hydroxyl functional groups of the glycerol molecule are esterified with fatty acids) containing fatty acid components C-chain lengths ranging from C12 (<5%) up to C18 unsaturated (>60%), whereas the target substance contains mainly mono and diesters (triester < 15%) and fatty acid C-chain lengths ranging from C14 (<15%) up to C18 unsaturated (30-85%). Biodegradation for both substances can be expected to be comparable in terms of carbon chain length of the individual fatty acid components (determined basically by the C18 unsaturated content). However, due to the lower triester content of Glycerides,C14-18 and C16-18 unsaturated, mono-, di- and tri-, a higher degree of biodegradation can be expected for this substance. Therefore, read-across from 1,2,3-propanetriyl trioleate would result in a worst-case assumption and therefore, it is justified.

Data evaluating the biodegradation potential of 1,2,3-propanetriyl trioleate (CAS No. 122-32-7) are available. A ready biodegradability test was conducted according to OECD Guideline 301B, under GLP conditions (Coenen, 1991). Activated sludge was exposed for 28 days to the test substance (at 10 and 20 mg/L) and biodegradation was followed by measuring CO2 production in the test vessels. After 28 days, the reference substance (sodium acetate) did not fulfil the validity criterion for this test (60% biodegradation was attained only after 20 days, instead of 14 days). However, considering the extensive observed biodegradation of the test substance in both 10 and 20 mg/L replicates (76.5%) and that 60% was biodegraded within the 10-day window, the results from this test are considered to be valid for further assessment. 

 

Based on the results obtained for the structurally related analogue substance (in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5), Glycerides,C14-18 and C16-18 unsaturated, mono-, di- and tri- can be considered as readily biodegradable.

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