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Environmental fate & pathways

Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 19.04.2017
- Purity test date: 100% UVCB
Radiolabelling:
no
Analytical monitoring:
yes
Buffers:
- pH: 4
- Composition of buffer: citric acid, sodium hydroxide, sodium chloride

- pH: 7
- Composition of buffer: phosphate mixture

- pH: 9
- Composition of buffer: boric acid, sodium hydroxide, potassium chloride
Estimation method (if used):
Arrhenius equation
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: amber coloured glass vials (50 mL)

TEST MEDIUM
- Volume used/treatment: 50 mL
- Preparation of test medium: 70-115 mg of the test item were dissolved in 100 mL methanol. Aliquots (2.5 mL) therefrom were pipetted each into a 100 mL volumetric flask and filled up to volume with methanol. From these solutions, aliquots (1 mL) were pipetted each into a 100 mL volumetric flask and filled up to volume with the respective buffer.
- Identity and concentration of co-solvent: < 1% methanol
Duration:
741 h
pH:
4
Temp.:
20 °C
Duration:
238 h
pH:
4
Temp.:
30 °C
Duration:
238 h
pH:
4
Temp.:
40 °C
Duration:
120 h
pH:
4
Temp.:
50 °C
Duration:
790 h
pH:
7
Temp.:
20 °C
Duration:
790 h
pH:
7
Temp.:
40 °C
Duration:
120 h
pH:
7
Temp.:
50 °C
Duration:
742 h
pH:
7
Temp.:
60 °C
Duration:
595 h
pH:
7
Temp.:
70 °C
Duration:
844 h
pH:
9
Temp.:
20 °C
Duration:
844 h
pH:
9
Temp.:
40 °C
Duration:
120 h
pH:
9
Temp.:
50 °C
Duration:
626 h
pH:
9
Temp.:
60 °C
Duration:
216 h
pH:
9
Temp.:
70 °C
Number of replicates:
2
Positive controls:
no
Negative controls:
no
Transformation products:
not specified
Remarks:
see attached background aterial
Key result
pH:
7
Temp.:
20 °C
DT50:
> 1 500 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
not determinable because of methodological limitations
Remarks:
no exact calculation because data show high variability
Key result
pH:
4
Temp.:
20 °C
DT50:
110.9 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: calculated from the measured data
Key result
pH:
9
Temp.:
20 °C
DT50:
1 486.6 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: calculated from the measured data
Details on results:
TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes

MAJOR TRANSFORMATION PRODUCTS
At pH5:
- Range of maximum concentrations in % of the applied amount and day(s) of incubation when observed:
- Range of maximum concentrations in % of the applied amount at end of study period:
on the - the and -th day of incubation, respectively. At the end of the study period, the corresponding concentrations were - and -- % of the applied amount, respectively.

At pH7:
- Range of maximum concentrations in % of the applied amount and day(s) of incubation when observed:
- Range of maximum concentrations in % of the applied amount at end of study period:
on the - the and -th day of incubation, respectively. At the end of the study period, the corresponding concentrations were - and -- % of the applied amount, respectively.

At pH9:
- Range of maximum concentrations in % of the applied amount and day(s) of incubation when observed:
- Range of maximum concentrations in % of the applied amount at end of study period:
on the - the and -th day of incubation, respectively. At the end of the study period, the corresponding concentrations were - and -- % of the applied amount, respectively.

MINOR TRANSFORMATION PRODUCTS
Maximum concentrations in % of the applied amount
- at pH5:
- at pH7:
- at pH9:

MINERALISATION (distinguish between dark and irradiated samples)
- % of applied radioactivity present as CO2 at end of study:

INDICATION OF UNSTABLE TRANSFORMATION PRODUCTS:

VOLATILIZATION (at end of study)
- Evolved CO2 in % of the applied: .. at pH 5, .. at pH 7, .. at pH 9
- Total volatile organics in % of the applied: .. at pH 5, .. at pH 7, .. at pH 9

UNIDENTIFIED RADIOACTIVITY (at end of study)
- at pH5:
- at pH7:
- at pH9:

PATHWAYS OF HYDROLYSIS
- Description of pathwayS:
- Figures of chemical structures attached: Yes/No

SUPPLEMENTARY EXPERIMENT (if any): RESULTS:
Validity criteria fulfilled:
yes
Conclusions:
The oxime group hydrolysis but slowly at environmentally relevant temperatures. Apart from that hydrolysis is reduced to the oxime group and do not significantly modify the structural characteristic and subsequently the ecotoxicological potential of the substance. Thus, abiotic hydrolysis is not considered to be a relevant degradation pathway of the substance in the environment and the hydrolysis products do not have to be considered toxicologically.

Description of key information

Hydrolysis is a negligible removal process for Benzaldehyde, 2-hydroxy-5-nonyl, oxime, branched (CAS 174333-80-3) in the aquatic environment.

Key value for chemical safety assessment

Additional information

One study is available investigating the abiotic degradation (hydrolysis as a function of pH) potential of Benzaldehyde, 2-hydroxy-5-nonyl, oxime, branched (CAS 174333-80-3). The key 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). This result is confirmed by The EU Risk Assessment Report 2002 (p.54), which 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).