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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The ready biodegradability of the substance was investigated by performing a study in accordance with OECD 301F (1992) and GLP.
The result of the key study was confirmed by other biodegradation studies found in the RIFM database. The non ready degradability of the substance was confirmed in a Modified Sturm test according to OECD301B. The substance is tested at 10 and 20 mg/L showed 34 and 12% degradation after 28 days, respectively. Two further studies to investigate the inherent degradability of the substance were performed. In a study according to OECD 302C the substance tested at 30 mg/L was found to be not inherently biodegradable, showing 12% and 18% biodegradation after 28 and 50 days, respectively. A further study to investigate the inherent degradability of the substance was performed. In a modified SCAS test according to OECD 302A the substance tested at 9.6 mg/L showed an average extent of mineralization (after 28 days) in the sealed vessel using an acclimatized inoculum of -0.2%, meaning that the substance cannot be classified as inherently ultimately biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The data are derived from Karanal, which is a reaction mass containing several components. Karanal consists of the same components as Aurawood but the as well as its composition but the concentration of these components are slightly different.

Though ECHA (GB349025-60, 2012, see attached) has responded that Karanal is not identical to Aurawood the constituents are the same and may be around the ECHA's threshold when considering Karanal and Aurawood dissimilar.

In IFFs view the similarity between these two substances is as such that an overall read across justification for biodegradation is not considered necessary also because the variation in the concentration of the components is not considered to influence the biodegradation results. Therefore the data of Karanal can be used for Aurawood. In the sections on test substance Karanal is considered the same as Aurawood.

The study was performed at 1 test concentration (100 mg/L based on test material) plus a blank control and a toxicity control. Test flasks were prepared using the standard procedure for applying the test substance (direct addition to medium with inoculum) and two alternative methods: ultrasound treatment and use of silicone oil. The substance undergoes no ultimate biodegradation after 28 days (1 % after 50 days) in the test conditions of OECD 301F with direct addition of the test substance. Using alternative substance application methods, i.e. the use of ultrasound to disperse the test substance and application of the test substance in silicone oil, did not improve the biodegradation of the substance (ultrasound treatment: biodegradation 0 % after 28 days, 2 % after 50 days; silicone oil: biodegradation -2% after 28 days, -2 % after 50 days). The test material was not toxic to the inoculum. As the tested concentration of the substance is far above the maximum water solubility of the substance (0.61 mg/L) it cannot be guaranteed that the test material was optimally available for the microorganisms. Therefore, the resulting biodegradation percentages probably provide an underestimation of the percentages that could be obtained under optimal conditions.