Benzaldehyde, 4-[(3-fluorophenyl)methoxy]-

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2 DEC 2014 - 7 JAN 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

OECD Guideline for Testing of Chemicals No. 301 F: "Ready Biodegradability: Manometric Respirometry Test", adopted July 17, 1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

Commission Regulation 440/2008/EC, Method C.4-D of May 30, 2008: Manometric Respirometry Test (EEC Publication No. L 142/496, May 2008)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Hess. Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz, 24 September 2013

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Aerobic activated sludge, microorganisms from a domestic waste water treatment plant was supplied by the sewage plant Rossdorf, Germany.
- Preparation of inoculum for exposure: The aerobic activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in tap water and centrifuged again. This procedure was done three times. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 3.5 g dry material per litre were mixed with test water and aerated overnight. This suspension was used for the experiment.
- Concentration of sludge: 3.5 g/L on dry matter base

Duration of test (contact time):

28 d

Initial conc.:

25 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Reconstituted Test water.
Analytical grade salts were added to deionised water to prepare the following stock solutions:
a) 8.5 g KH2PO4, 21.75 g K2HPO4, 33.4 g Na2HPO4 x 2 H2O, 0.5 g NH4Cl filled up with deionised water to 1000 mL volume; The pH-value was 7.4.
b) 11.25 g MgSO4 x 7 H2O filled up with deionised water to 500 mL volume
c) 18.2 g CaCl2 x 2 H2O filled up with deionised water to 500 mL volume
d) 0.125 g FeCl3 x 6 H2O filled up with deionised water to 500 mL volume
In order to avoid precipitation of iron hydroxide in the stock solution d) after storage and before use, one drop of concentrated HCl per litre was added.
50 mL of stock solution a) and 5 mL of the stock solutions b) to d) were combined and filled up to a final volume of 5000 mL with deionised water.
- Test temperature: The temperature was recorded by means of the automated software AMR Wincontrol© and was in the range of 22°C ± 1°C.
- pH: pH-values were measured in procedure control, a separately prepared test flask with test item (to prevent loss of test item in the test flasks) and a separately prepared test flask without test item (control) at test start and in all flasks at the end of the test, except in the abiotic and toxicity control, using a pH-electrode WTW pH 340i.
7.5 to 7.6 (measured at the start of the test)
7.3 to 7.9 (measured at the end of the test)
- pH adjusted: no
- Aeration of dilution water: not specified
- Suspended solids concentration: Stock suspension of 3.5 g/L activated sludge based on dry matter (final sludge concentration in test flasks: 28.7 mg sludge/L).
- Continuous darkness: yes
- Other: Climatised room

TEST SYSTEM
- Culturing apparatus: Manometric Test System with test flasks containing a volume of approximately 500 mL.
- Number of culture flasks/concentration: 2
- Measuring equipment: The pressure decrease in the reaction vessels was measured over complete experimental phase of 28 days using the BSB/BOD-Sensor-System, Aqualytic Dortmund, Germany.
- Test performed in open system: No. The test flasks were closed gas-tight by a measuring head.
- Details of trap for CO2 and volatile organics if used: Potassium hydroxide solution (45%) was used for trapping the produced carbon dioxide.
- Other: The amount of O2 consumed by the activated sludge was calculated from the decrease of pressure in the reaction vessel.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 flasks containing test water and activated sludge.
- Procedure control: 1 flask containing the reference item sodium benzoate, test water and activated sludge
- Abiotic sterile control: 1 flask containing the test item and test water poisoned with HgCl2 (stock solution of 1 g/L)
- Toxicity control: 1 flask containing the test item, the reference item sodium benzoate, activated sludge and test water

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Remarks:

ThODNH4

Value:

46

Sampling time:

28 d

Details on results:

- Percentage Biodegradation Test Item:
The criterion for ready biodegradability under the conditions of a manometric respirometry test is the 10-day window, describing the period between reaching at least 10% degradation and 60% degradation. This period should not exceed 10 days.
The 10-day window started at day 13, when the biodegradation was 10%. At the end of the 10-day window at day 23, the biodegradation was 44% and therefore the 10 day window criterion was not passed. The degradation of the test substance increased till day 27 when a plateau was reached, the maximum degradation was 47%; at the end of the test at day 28 the degradation was 46% (ThODNH4).
Hence, the degradation rate of the test substance did not reach 60% within the 10-day window or after 28 days. Therefore, the test substance is considered to be not readily biodegradable.
- Percentage Biodegradation Toxicity Control:
In the toxicity control containing both, the test item and the reference item sodium benzoate, 42% (ThODNH4) biodegradation was noted within 14 days and 69% after 28 days of incubation. According to the test guidelines, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.
- Oxygen Demand Abiotic Control:
The oxygen demand in the abiotic control was 0 mg/L during the test duration. There was no use to correct the degradation of the test item and toxicity control.

Results with reference substance:

The reference item sodium benzoate was sufficiently degraded to 81% after 14 days and to 82% after 28 days of incubation.
Hence, the percentage biodegradation of the reference item confirms the suitability of the used aerobic activated sludge inoculum.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The study was conducted under GLP according to OECD 301 F and the Commission Regulation 440/2008/EC, C.4-D on the registered substance itself. The method is to be considered scientifically reasonable and suitable for the test item with detailed documentation. Hence, the results can be considered as reliable to assess the ready biodegradability of the test substance. Based on the obtained results the degradation rate of the test substance did not reach 60% within the 10-day window or after 28 days. Hence, the test substance is considered to be not readily biodegradable. biodegradable.

Executive summary:

The study was conducted under GLP according to OECD Guideline 301 F and EU Method C.4 -D at a nominal concentration of 25 mg test substance/L for 28 days. Sodium benzoate served as reference item for the positive control.

The criterion for ready biodegradability under the conditions of a manometric respirometry test is the 10-day window, describing the period between reaching at least 10% degradation and 60% degradation. This period should not exceed 10 days.

The 10-day window started at day 13, when the biodegradation was 10%. At the end of the 10-day window at day 23, the biodegradation was 44% and therefore the 10 day window criterion was not passed. The degradation of the test substance increased till day 27 when a plateau was reached, the maximum degradation was 47%; at the end of the test at day 28 the degradation was 46% (ThOD_NH4).

The degradation rate of the test substance did not reach 60% within the 10-day window or after 28 days. Therefore, the test substance is considered to be not readily biodegradable.

Description of key information

Key, Biodegradation in water: screening test, OECD TG 301 F, GLP: Not readily biodegradable: 46% (ThOD_NH4) in 28 days

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

The study was conducted under GLP according to OECD Guideline 301 and EU Method C4 -D at a nominal concentration of 25 mg test substance/L for 28 days. Sodium benzoate served as reference item for the positive control.

The criterion for ready biodegradability under the conditions of a manometric respirometry test is the 10-day window, describing the period between reaching at least 10% degradation and 60% degradation. This period should not exceed 10 days.

The 10-day window started at day 13, when the biodegradation was 10%. At the end of the 10-day window at day 23, the biodegradation was 44% and therefore the 10 day window criterion was not passed. The degradation of the test substance increased till day 27 when a plateau was reached, the maximum degradation was 47%; at the end of the test at day 28 the degradation was 46% (ThOD_NH4).

The degradation rate of the test substance did not reach 60% within the 10-day window or after 28 days. Therefore, the test substance is considered to be not readily biodegradable.