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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Readily biodegradable

Key value for chemical safety assessment

Additional information

No study on biodegradation in water is available for azelaic acid. Therefore, read across from the key studies of a shorter (octanoic acid, C8) and a longer-chain fatty acid (lauric acid, C12), which are members of the fatty acid category, was conducted.

The data from octanoic acid are covered with the most appropriate and reliable study from Richterich and Mühlberg (2004). The study was performed according to OECD 301D (non-GLP) where octanoic acid was tested at concentrations of 2 and 5 mg/L for 30 days. At a test substance concentration of 5 mg/L more then 72 % was degraded within 30 days. Due to the good biodegradability at 5 mg/L, the oxygen concentration remained inadequate so that the 72% degradation should be regarded as a minimum value. At a test concentration of 2 mg/L octanoic acid was completely degraded. 60% degradation was reached within the 10 day window as required. Thus, the surrogate octanoic acid can be regarded as readily biodegradable.

The read across from lauric acid (C12) to azelaic acid (C9) is based on the key study of lauric acid.
Richterich and Mühlenberg (2001) conducted a closed bottle test according to OECD 301D. After 30 days 86% oxygen consumption at a substance concentration of 2 mg/L and 62% at 5 mg/L were observed. The criterion for ready biodegradability, the 10-day window, was met.

Based on the ready biodegradability of both analogue substances, octanoic acid and lauric acid, azelaic acid can be regarded as readily biodegradable, too.
This judgment is consistent with the hazard assessment presented in the OECD SIDS (2009) for the category “Aliphatic Acids Category” where aliphatic fatty acids with a carbon chain length in the range of C8 – C22 were judged to be readily biodegradable.

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