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Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1999-10-14 to 1999-11-12
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
GLP
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Version / remarks:
31st July 1992
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
17th July 1992
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
not applicable
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): water treatment plant Emeraude (SIARR), Petit-Quevilly, France, 1999-10-06
- Preparation of inoculum for exposure: initial sieving of sewage sludge, 5 min centrifugation, rejection of supernatant, redispersion of pellet in mineral medium
- Pretreatment: to wash out DOC, preconditioning for 6 days (air was bubbled through the inoculum during preconditioning), 22 ± 2°C
- Concentration of sludge: 12 mg/L (dry weight)
- Initial cell/biomass concentration: no data
- Water: reconstituted deionised water containing no more than 10% of the organic carbon introduced by addition of test substance / reference substance
Duration of test (contact time):
29 d
Initial conc.:
10 mg/L
Based on:
other: TOC
Initial conc.:
17.03 other: mg/flask
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: according to OECD guideline 301
- Test temperature: 19 – 22°C
- pH: at beginning of the test 7.53; day 28: 8.20 to 8.60
- pH adjusted: no
- Aeration of dilution water: flasks were bubbled with CO2-scrubbed air at 30 – 100 mL/min
- Suspended solids concentration: 12 mg/L
- Continuous darkness: yes (dark glass bottles fitted with dark glass stoppers)
- other: stirring with magnetic stirrer to homogenate the culture

TEST SYSTEM
- Culturing apparatus:
- Number of culture flasks/concentration: 2/ inoculum blank, 2/test substance, 1/reference substance
- Method used to create aerobic conditions: aeration (flasks were bubbled with CO2-scrubbed air at 30 – 100 mL/min)
- Details of trap for CO2: series of 3 wash bottles filled with 100 mL 0.0125 M barium hydroxide

SAMPLING
- Sampling frequency: days 1, 4, 6, 8, 11, 14, 15, 21, 25, 29
- Sampling method: The CO2 produced by degradation was collected in a series of 3 wash bottles filled with 100 mL 0.0125 Ba(OH)2. The amount of CO2 was calculated by titration of the Ba(OH)2 solution with 0.05 M HCl, using phenolphthalein as indicator.
- Sterility check if applicable: no
- Sample storage before analysis: no data, probably immediate analysis

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (2 flasks)
- Abiotic sterile control: no
- Toxicity control: no
- Other: reference substance (sodium acetate)
Reference substance:
acetic acid, sodium salt
Remarks:
10 mg TOC/L
Preliminary study:
n/a
Test performance:
n/a
Parameter:
% degradation (CO2 evolution)
Value:
85
Sampling time:
28 d
Parameter:
% degradation (CO2 evolution)
Value:
61
Sampling time:
17 d
Remarks on result:
other: end of 10 day window
Details on results:
The 10-day window (the 10 days immediately following the attainment of 10% biodegradation of the test substance) started on day 7. Biodegradation totalled 61% (mean of the two flasks) at the end of the 10-day window (day 17) and 85% at the end of the test period.
Results with reference substance:
The reference substance degraded normally under the test conditions (68.5% after 14 days).

On day 28, 1 mL conc. HCl was added to each flask to stop biodegradation and aerated overnight to drive off the remaining CO2. A final CO2 analysis was made on day 29 being representative of biodegradation of day 28.

 

Validity criteria

- biodegradation values of the test substance do not deviate by more than 20% at the end of the study

- biodegradation of the reference substance >60% after 14 days

- blank value <70 mg CO2/L at the end of the study

 

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The ready biodegradation of TREGDMA was investigated in a CO2 evolution test over a period of 28 days and using domestic sewage as inoculum. Inoculum blank and procedural/functional control with the reference substance sodium acetate were performed.
The 10-day window started on day 7. Biodegradation totalled 61% at the end of the 10 day window (day 17) and 85% at the end of the test period. The test item proved to be readily biodegradable and fulfilling the 10-d window criterion.
Executive summary:

The ready biodegradation of TREGDMA was investigated in a study conducted according to OECD Guideline 301 B (CO2 evolution test), adopted 17th July 1992, and EU Method C.4 -C, 31 July 1992, over a period of 28 days using sewage sludge sampled from the aeration tank of a predominantly domestic sewage treatment plant as inoculum. The biodegradation rate was determined by measurement of CO2 evolution. Inoculum blank and procedural/functional control with the reference substance sodium acetate were performed.

The test item proved to be readily biodegradable and fulfilling the 10-d window criterion.

The 10-day window started on day 7. Biodegradation totalled 61% at the end of the 10 day window (day 17) and 85% at the end of the test period. The functional control reached the pass level >60% after 14 d (68.5%).

This study is regarded as reliable without restriction and satisfies the guideline requirements for ready biodegradation. TREGDMA proved to be readily biodegradable and fulfilling the 10-d window criterion.

NOTE: Any of data in this dataset are disseminated by the European Union on a right-to-know basis and this is not a publication in the same sense as a book or an article in a journal. The right of ownership in any part of this information is reserved by the data owner(s). The use of this information for any other, e.g. commercial purpose is strictly reserved to the data owners and those persons or legal entities having paid the respective access fee for the intended purpose.

Description of key information

TREGDMA proved to be readily biodegradable and fulfilling the 10-d window criterion.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

One study on biodegradation of TREGDMA is available, which is considered as reliable without restrictions (Klimisch score 1):

The ready biodegradation of TREGDMA was investigated in a study conducted according to OECD Guideline 301 B (CO2 evolution test), adopted 17th July 1992, and EU Method C.4 -C, 31 July 1992, over a period of 28 days using sewage sludge sampled from the aeration tank of a predominantly domestic sewage treatment plant as inoculum. The biodegradation rate was determined by measurement of CO2 evolution. Inoculum blank and procedural/functional control with the reference substance sodium acetate were performed.

The test item proved to be readily biodegradable and fulfilling the 10-d window criterion.

The 10-day window started on day 7. Biodegradation totalled 61% at the end of the 10 day window (day 17) and 85% at the end of the test period. The functional control reached the pass level >60% after 14 d (68.5%).