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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
adopted 17. Jul. 1992
Deviations:
yes
Remarks:
Temperature range was 19.7 – 21.9 °C instead of 20.0 – 24.0 °C. As degradation of the positive control was in the normal range this is considered as uncritical concern-ing the outcome of the study.
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Version / remarks:
adopted 30. May 2008
Deviations:
yes
Remarks:
Temperature range was 19.7 – 21.9 °C instead of 20.0 – 24.0 °C. As degradation of the positive control was in the normal range this is considered as uncritical concern-ing the outcome of the study.
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
- Name of test material: 4,4'-bis(2-methoxystyryl)-1,1'-biphenyl
- IUPAC name: 1-[(E)-2-(2-methoxyphenyl)ethenyl]-4-{4-[(E)-2-(2-methoxyphenyl)ethenyl]phenyl}benzene
- Molecular formula: C30H26O2
- Molecular weight: 418.53 g/mol
- Smiles notation: COC1=CC=CC=C1/C=C/C2=CC=C(C3=CC=C(/C=C/C4=CC=CC=C4OC)C=C3)C=C2
- InChl: 1S/C30H26O2/c1-31-29-9-5-3-7-27(29)21-15-23-11-17-25(18-12-23)26-19-13-24(14-20-26)16-22-28-8-4-6-10-30(28)32-2/h3-22H,1-2H3/b21-15+,22-16+
- Substance type: Organic
- Physical state: Solid

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, 67435 NW-Lachen-Speyerdorf.
Date of collection: 17. Aug. 2018, batch no: 20180817.
- Preparation of inoculum for exposure: 72h
- Pretreatment: The sludge was filtrated, washed with test medium (2x) and re-suspended in test medium. It was then aerated until use. The dry matter was determined to contain 5000 mg of sus-pended solids/L.
- Concentration of sludge: 25.0 mg dry matter/L
- Water filtered: yes.
- Type and size of filter used, if any: The sludge was filtrated, washed with test medium (2x) and re-suspended in test medium.
Duration of test (contact time):
ca. 28 d
Initial test substance concentration
Initial conc.:
ca. 20 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: mineral medium
- Test temperature: 19.7 – 21.9 °C
- Suspended solids concentration: 5000 mg of suspended solids/L
- Continuous darkness: yes

TEST SYSTEM
- Measuring equipment: Analyses of the emitted CO2 were made by IC measurement using the carbon analyser TOC multi N/C 2100S, Analytik Jena. Each sample was measured in duplicate or triplicate, respectively (depending on the variation between the measured values).
- Test vessels: The test vessels were aerated with purified (by activated charcoal), CO2-scrubbed, mois-tened air. 2000 mL-SCHOTT-flasks were used as test vessels, 100 mL scrubber flasks as absorbent vessels.

SAMPLING
From each front scrubber flask, 11 samples were taken in order to determine the emitted CO2 (on day 0, 2, 4, 7, 9, 11, 14, 18, 23*, 24 and 29). The sample volume was 1 mL. The resulting change in the volume of the front flask was considered in the calculation of emitted CO2 (see also chapter 8.3.1).
On day 28, 5 mL HCl 2 M was added to each test flask in order to drive off dissolved CO2. On day 29, samples from both scrubber flasks were taken.
*due to error of the carbon analyser on day 23 the measured samples gave wrong results. Therefore, samples were taken on day 24. The results of the samples on day 23 were not used for evaluation.


CONTROL AND BLANK SYSTEM:
- Positive control: Aniline (Phenylamine, C6H5NH2, CAS-No. 62-53-3) was used as readily biodegradable positive control.
- Apparatus blanks: 2, containing mineral medium only
- Blank Controls: 2, containing mineral medium and inoculum
- Positive control flasks 2, containing positive control, mineral medium and inoculum
- Test flasks 2, containing test item, mineral medium and inoculum
- Abiotic control 1, containing test item, mineral medium and HgCl2
- Toxicity control 1, containing test item, positive control, mineral medium and inoculum

STATISTICAL METHODS:

Results and discussion

Preliminary study:
Not available
Test performance:
Not available
% Degradation
Key result
Parameter:
% degradation (test mat. analysis)
Value:
3
Sampling time:
28 d
Details on results:
Degradation behaviour of positive control and toxicity control was normal. Abiotic degradation reached 7.2 %. Both replicates of the test item showed very good correspondence.
If degradation in the toxicity flask is below 25 % after 14 days, the test item can be consid-ered as toxic towards the inoculum. As degradation in the toxicity flask was 38.5 % after 14 days, the test item can be stated as “not toxic towards the inoculum in a concentration of 23.2 mg/L”.
Due to error of the carbon analyser on day 23 the measured samples gave wrong results. Therefore, samples were taken on day 24. The results of the samples on day 23 were not used for evaluation.
No observations were made which might cause doubts concerning the validity of the study outcome.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The test item 4,4'-bis(2-methoxystyryl)-1,1'-biphenyl is not readily biodegradable following OECD 301B and EU C.4-C respectively. As degradation missed 60% in the course of the test, 4,4'-bis(2-methoxystyryl)-1,1'-biphenyl is considered as not ultimately biodegradable.
Executive summary:

In the guideline of OECD 301B and EU C.4-C respectively, the biodegradation of the test material (EC 254-935-6) was determined to be 3% within 28 days. The test was conducted using an aerobic activated sewerage sludge taken from a biologic sewage treatment plant. Based upon the result of the study, the test material should be considered not readily biodegradable under the criteria of the OECD 301B and EU C.4-C respectively.