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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Not readily biodegradable: 1% biodegradation in 28 days test period (ISO 10708, BODIS test)

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

One test investigating the ready biodegradability of Ethanone, 1-(2-hydroxy-5-nonylphenyl)-, oxime, branched (CAS

244235-47-0) is available. The test was performed according to GLP and ISO guideline 10708 (BOD adapted to insoluble test substances) using non-adapted activated sludge as inoculum (Richterich 1996). Only 1% biodegradation was observed in a test period of 28 days (based on oxygen consumption). Thus, the test substance is not readily biodegradable.

Since no additional study assessing the inherent biodegradability of Ethanone, 1-(2-hydroxy-5-nonylphenyl)-, oxime, branched (CAS 244235-47-0) is available, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 Grouping of substances, a read-across to the structurally related source substance Benzaldehyde, 2-hydroxy-5-nonyl, oxime, branched (CAS 174333-80-3) was conducted. The only structural difference between the source substance and the target substance is the lack of a methyl group at the oxime carbon of the source substance. The read across is justified due to (i) the similarity of structure and functional groups and accordingly (ii) similar physico-chemical properties resulting in a similar environmental fate and ecotoxicity profile (see table below).

Table 1: Physico-chemical properties and ecotoxicological profile of the target and the source substance


Ethanone, 1-(2-hydroxy-5-nonylphenyl)-, oxime, branched

Benzaldehyde, 2-hydroxy-5-nonyl, oxime, branched

CAS number




see attachment

see attachment

Molecular formula



Molecular weight

~ 277 g/mole

~ 263 g/mole

PC parameter



Water solubility

> 0.02 < 1 mg/L (EU method A.6)

0.4 mg/L (EU method A.6)

Partition coefficient

> 5.7 (EU method A.8)

5.5 (EU method A.8)

Vapour pressure

< 1.5 Pa at 20 °C (OECD 104)

0.37 Pa at 20 °C (OECD 104)

Environmental fate




1 % in 28 days (BODIS)

0 % in 28 days (OECD 302c)

Adsorption [log KOC]

3.9 (OECD 121)

3.7 (OECD 121)


not relevant




Short-term toxicity to fish


0.46 mg/L (EU method C.1)

1.1 mg/L (EU method C.1)

Short-term toxicity to aquatic invertebrates


9.55 mg/L (OECD 202)

2.7 mg/L (EU method C.2)

Long-term toxicity to aquatic invertebrates


2.8 mg/L (OECD 211)

0.189 mg/L (OECD 211)

Short-term toxicity to algae


760 mg/L (OECD 201)

36.3 mg/L (OECD 201)

Long-term toxicity to algae


472 mg/L (OECD 201)

14.9 mg/L (OECD 201)

Toxicity to microorganisms


260.1mg/L (OECD 209)

200.4 mg/L (OECD 209)

The inherent biodegradation study with the source substance was performed according to GLP and OECD guideline 302C using non-adapted activated sludge as inoculum (Seyfried 2007). The biochemical oxygen demand (BOD) of the test substance in the test media was in the normal range found for the inoculum controls. Consequently, the test substance was not inherently biodegradable under the test conditions within 28 days. Based on the high structural similarity, which leads to similar behavior in the environment (as explained above), this conclusion can also considered to be true for Ethanone, 1-(2-hydroxy-5-nonylphenyl)-, oxime, branched (CAS 244235-47-0).

In addition, several screening tests for 4-nonylphenol are available (see table 2). In general, these tests show that 4-nonylphenol is not readily biodegradable according to OECD criteria (MITI 2002, Huels 1996 a,b). Degradation is observed if adapted inoculum was used (Staples et al. 1999, 2001) indicating 4-nonylphenol to be inherently biodegradable. However, the degradation potential is depending on several factors, such as the branching of the alkyl chain (see Corvini et al. 2006).

Table 2: Biodegradation test results for 4-nonylphenol*






0% after 14 days


MITI 2002


47.5% after 28 days (adapted inoculum)


Staples et al. 2001


57.4 – 68.4% after 28 days (adapted inoculum)


Staples et al. 1999


0 % after 32 days (with and without emulsifier)

with adopted inoculum (adaption time 7 weeks):

0 % after 40 days (without emulsifier)

78 % after 40 days (with emulsifier)


(EU RAR 2002, Huels 1996a; Huels 1996b)

* Data obtained from the respective dossier published on the ECHA data base and from EU RAR 2002.

The two minor constituents phenol (CAS 108-95-2) and 2-ethylhexanoic acid (CAS 149-57-5) showed to be readily biodegradable based on available test data or valid QSAR calculations.


MITI 2002. Biodegradation and Bioconcentration of Exisiting Chemical Substances under the Chemical Substances Control Law. Information on the chemical published in the Official Bulletin of Economy, Trade and Industry.

Staples CA, et al. 2001. Ultimate biodegradation of alkylphenol ethoxylate surfactants and their biodegradation intermediates. Environ Toxicol Chem 20(11): 2450–2455

Staples CA, et al. 1999. Measuring the biodegradability of nonylphenol ether carboxylates, octylphenol ether carboxylates, and nonylphenol. Chemosphere 38(9): 2029-2039

EU RAR.2002. European Union Risk Assessment Report 4-nonylphenol (branched) and nonylphenol.

Huels. 1996a. Determination of the biological degradability of nonylphenol in the modified sturm test (EEC Directive 79/831 ENV/283/80) Report ST-3/84

Huels. 1996b. Determination of the biological degradability of nonylphenol in the modified sturm test (EEC Directive 79/831 ENV/283/80) Report ST-3a/84.