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Description of key information

Hydrolysis is a negligible removal process for Ethanone, 1-(2-hydroxy-5-nonylphenyl)-, oxime, branched (CAS 244235-47-0) in the aquatic environment.

Key value for chemical safety assessment

Additional information

In accordance with Annex XI, subitem 2. Testing is technically not possible, of Regulation (EC) No. 1907/2006, testing for hydrolysis as a function of pH may be omitted, if the test is technically not possible to conduct. The substance is very poorly soluble in water (> 0.02 < 0.1 mg/L determined in an appropriate test method [VTA34N00003.01] which complies with EU method A.6, see 4.8 for details). In order to improve the solubility in water, a stock solution of the test item is prepared in acetone (50 mg test substance in 2 mL). When adding the stock solution to 1000 mL of water, a white precipitate is produced immediately. Thus, the test is technically not possible to conduct, since the practical insolubility of the test substance impedes a proper analytics.

In addition, the EU Risk Assessment Report (2002) states that hydrolysis is a negligible removal processes for nonylphenol in the aquatic environment. This assumption is based upon the stability of nonylphenol during storage and several biodegradation studies reviewed by the UK rapporteur on behalf of the European Union where no degradation was observed in the control experiments. The authors of these studies concluded that abiotic degradation was likely to be negligible (Corti et al. 1995, Trocmé et al. 1988; both cited in the EU Risk Assessment Report 2002). Based on the structural similarity this conclusion is also considered to be true for Ethanone, 1-(2-hydroxy-5-nonylphenyl)-, oxime, branched (CAS 244235-47-0).

This is confirmed by one study investigating the abiotic degradation (hydrolysis as a function of pH) potential of the structurally similar Benzaldehyde, 2-hydroxy-5-nonyl, oxime, branched (CAS 174333-80-3). This study was performed according to OECD guideline 111 under GLP conditions (BASF 2018). The test was performed at different pH values over an exposure time of up to 790 h. Hydrolysis is very slow and reduced to the oxime group and thus do not significantly modify the structural characteristic and subsequently the (eco)toxicological potential of the substance. Hence, the hydrolysis products do not have to be considered separately in the hazard assessment. in conclusion, abiotic hydrolysis is not considered to be a relevant degradation pathway of the substance at environmentally relevant conditions (e.g., temperature).

Based on the structural similarity the same conclusion can be drawn for Ethanone, 1-(2-hydroxy-5-nonylphenyl)-, oxime, branched.