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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Readily biodegradable: 86% (O2 consumption) of isononanoic acid, C16-18 alkyl esters after 30 d (OECD 301D)

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

One study investigating the ready biodegradability of isononanoic acid, C16-18 alkyl esters (CAS 111937-03-2) according to the OECD 301D is available (Richterich, 2009). Domestic sewage was used as inoculum and two concentrations of the test substance were tested (2 and 5 mg/L). A mean degradation of 86% was observed after 30 days for the test concentration of 2 mg/L and > 56% for the test concentration of 5 mg/L. However, due to the high O2-consumption in the second test concentration (5 mg/L), only inadequate O2-concentrations remained in the test system (< 0.3 mg/L) and the result was not taken into account for the assessment. The 10- and even the 14-day window was not achieved. Since isononanoic acid, C16-18 alkyl esters is a UVCB substance and consists of structurally similar constituents with [e.g. different chain-lengths, degree and/or site of branching or stereo-isomers], sequential (instead of concurrent) biodegradation of the individual structures can take place, but all can be considered as readily biodegradable. Thus, referring to Annex I to the OECD Guideline for Testing of Chemicals ‘Revised introduction to the OECD guidelines for testing of chemicals, section 3’ (OECD, 2006), the 14-day window should not be considered for this UVCB substance and due to a degradation of > 60 % within 30 days the substance can be regarded as readily biodegradable.