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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report Date:
2019

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid
Specific details on test material used for the study:
Appearance creamish white to yellow pellets
Composition hydrogenated decyl esters of olive oil fatty acids
CAS No. 438551-82-7
EINECS-No. 924-579-2
Molecular formula unknown
Molecular weight unknown
Purity 100% (UVCB)
Homogeneity homogeneous
Vapour pressure unknown
Stability in solvents H2O: not stated; EtOH: not stated; acetone: not stated; CH3CN: not stated; DMSO: not stated
Solubility in solvents H2O: < 0.1g/L; EtOH: > 1g/L; acetone: > 1g/L; CH3CN: > 1g/L; DMSO: > 1g/L
Production date 11. Dec. 2017
Expiry date 11. Dec. 2019
Storage Freezer (-15 - -25°C)

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
Specification
Activated sludge from a biologic sewage treatment plant was used as inoculum. The cho-sen plant treats mostly domestic sewage.

Source and Pre-Treatment of inoculum
-Source
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.
-Pre -Treatment
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.
Duration of test (contact time):
ca. 28 d
Initial test substance concentration
Initial conc.:
ca. 20 mg/L
Based on:
TOC
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
Preparation:
The medium was prepared from the stock solutions. The stock solution of the positive control was prepared and its DOC was measured. The inoculum was taken from its source, washed, aerated and the dry matter was determined.
The test vessels were filled with medium and inoculum. Then, all flasks were aerated for 72 hours with purified, CO2-free, moistened air to purge the system of CO2.

Experimental parameters:
Flask volume 1500 mL
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
Inoculum concentration: 25.0 mg/L
Temperature 19.7 – 21.9 °C
Duration 28 days
The test was performed with a nominal start concentration of 20 mg organic carbon/L of the test item.

Apparatus:
The test vessels were aerated with purified (by activated charcoal), CO2-scrubbed, moistened air. The scrubbing of carbon dioxide was achieved by bubbling the purified air through a flask containing 1.5 M NaOH. To control the absence of CO2, the air was then led through a flask containing a solution of Ba(OH)2 before reaching the test vessels.
Magnetic stirrers were used to prevent deposition of inoculum.
The emitted CO2 was trapped in 0.25 M NaOH. Two scrubbers containing 100 mL each were connected in series to the test vessels. The initial IC value of the 0.25 M NaOH was separately determined in each flask.


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, sam-ples were taken on day 24. The results of the samples on day 23 were not used for evaluation.
Reference substance
Reference substance:
aniline

Results and discussion

% Degradation
Key result
Parameter:
% degradation (CO2 evolution)
Value:
ca. 11
Sampling time:
28 d

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Executive summary:

The test item Hydrogenated olive oil stearyl ester was tested using a concentration of nom-inally 20 mg organic carbon/L Hydrogenated olive oil stearyl ester in test medium following OECD 301B and EU-Method C.4-C.

The following data were determined for the test item Hydrogenated olive oil stearyl ester:

10-day-window: not detected

degradation at the end of the test : 11 %

pass level following guideline: 60 % at the end of 10-day-window for pure substances, respective 60 % at the end of the test for mixtures

Therefore, when applying the 10-day-window, Hydrogenated olive oil stearyl ester is not readily biodegradable following OECD 301B and EU C.4-C respectively.