Registration Dossier

Diss Factsheets

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

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:
March 24-May 19, 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Identification: Jeffamine EDR 148
- Source and lot/batch No.of test material: 4M413
- Expiration date of the lot/batch: 31 December 2016

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature in the dark
- Stability under test conditions: No lack of stability indicated
- Solubility and stability of the test substance in the solvent/vehicle: Soluble in mineral medium

OTHER
- Physical state/Appearance: clear colorless liquid
- Purity: 97.5%
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Aeration stage sludge, Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK, which treats predominantly domestic sewage.
- Storage conditions: Under continuous aeration at 21 degrees C until use
- Storage length: Used on the day of collection
- Preparation of inoculum for exposure: washed twice by settlement and re-suspension in mineral medium to remove any excessive amounts of dissolved organic carbon (DOC)
- Concentration of sludge: suspended solids concentration = 3.8 g/L
- Water filtered: yes
- Type and size of filter used, if any: GF/A filter in Buchner funnel (rinsed three times with 20 mL deionized reverse osmosis water prior to drying in an oven)
Duration of test (contact time):
> 0 - <= 29 d
Initial conc.:
10 mg/L
Based on:
TOC
Initial conc.:
20.6 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: Mineral medium per OECD Guidline
- Test temperature: 23-25 degrees C
- pH:
*Day 0: pre-adjustment: 7.7 - 8.0
*Day 0: post-adjustment: 7.4-7.6
*Day 28: 7.4
- pH adjusted: yes
- Aeration of dilution water: yes, CO2-free air
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes
- Other:
* preliminary work: adsorption to filter material was was investigated.
* test item preparation: test item was dissolved directly in mineral medium

TEST SYSTEM
- Culturing apparatus: 5 L volumetric flasks, containing 3 L test solution
- Number of culture flasks/concentration: 2
- Measuring equipment: samples were analyzed for IC and TC using a Shimadzu TOC-VCPH TOC Analyzer.
- Method used to create aerobic conditions: aeration with CO2-free air
- Test performed in closed vessels due to significant volatility of test substance: no
- Details of trap for CO2 and volatile organics if used: 500 ml Dreschel bottles containing 350 ml 0.05 M NaOH

SAMPLING
- Sampling frequency:
* from first CO2 absorber vessels: Day 0, 2, 6, 8, 10, 14, 21, 28, 29
* from second absorber vessels: Days 0 and 29
- Sampling method:
* 2 ml from CO2 absorber vessels. On Day 28, 1 mL of concentrated HCl was added to each vessel to drive off any inorganic carbonates formed. The vessels were resealed, aerated overnight and the final samples taken from both absorber vessels on Day 29. * 30 mL samples were removed from inoculum control and test item vessels on Day 0 and filtered through 0.45 μm Gelman AcroCap filters (first approximate 5 mL discarded in order to pre-condition the filter) prior to DOC analysis.
- Sample storage before analysis: frozen
- Other: Appearance of the test preparations was recorded on Days 0, 6, 13, 20 and 27

CONTROL AND BLANK SYSTEM
- Inoculum control: yes
- Procedure control: yes
- Toxicity control: yes

Reference substance:
benzoic acid, sodium salt
Preliminary study:
Preliminary Investigational Work:
In order to investigate whether the test item adsorbed to filter matrices and/or the activated sewage sludge samples were analyzed for Dissolved Organic Carbon (DOC) using a Shimadzu TOC-VCPH TOC analyzer. The results obtained from the samples taken for DOC analysis from the preliminary investigational work indicated that the test item did not adsorb to filter matrices or to activated sewage sludge. Therefore, for the purpose of the study, the samples taken for DOC analysis were filtered to remove the suspended solids present without the loss of any test item.
Test performance:
Test satisfied the validation criteria per OECD Guideline
Key result
Parameter:
% degradation (CO2 evolution)
Value:
9
Sampling time:
29 d
Details on results:
Theoretical amount of CO2 was calculated as IC in test flask-IC in control flask/TOC added as test chemical. Percent degradation was found to be 9%.
Results with reference substance:
Sodium benzoate attained 85% biodegradation after 14 days and 107% biodegradation after 28 days thereby confirming the suitability of the inoculum and test conditions. Biodegradation values in excess of 100% were considered to be due to sampling/analytical variation.
Validity criteria fulfilled:
yes
Remarks:
On Day 25, 26 temperature in a vessel containing water and incubated under same conditions as the test vessels was 24.8°C. This was a deviation from the Study Plan but did not affect the integrity of the study given that all validation criteria were met.
Interpretation of results:
not readily biodegradable
Conclusions:
The test item attained 9% biodegradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301B.
Executive summary:

A study was performed to assess the ready biodegradability of the test item in an aerobic aqueous medium. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (1992) No. 301B, "Ready Biodegradability; CO2 Evolution Test" referenced as Method C.4-C of Commission Regulation (EC) No. 440/2008 and US EPA Fate, Transport, and Transformation Test Guidelines OCSPP 835.3110 (Paragraph (m)).

The test item, at a concentration of 10 mg carbon/L, was exposed to activated sewage sludge micro-organisms with mineral medium in sealed culture vessels in the dark at temperatures of between 23 and 25 °C for 28 days.

The biodegradation of the test item was assessed by the determination of carbon dioxide produced. Control solutions with inoculum and the reference item, sodium benzoate, together with a toxicity control were used for validation purposes.

The test item attained 9% biodegradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301B.

Description of key information

A study was performed to assess the ready biodegradability of the test item in an aerobic aqueous medium.

The test item, at a concentration of 10 mg carbon/L, was exposed to activated sewage sludge micro-organisms with mineral medium in sealed culture vessels in the dark at temperatures of between 23 and 25 °C for 28 days.

The biodegradation of the test item was assessed by the determination of carbon dioxide produced. Control solutions with inoculum and the reference item, sodium benzoate, together with a toxicity control were used for validation purposes.

The test item attained 9% biodegradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301B.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information