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
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)
Version / remarks:
version adopted July 17, 1992
Deviations:
yes
Remarks:
not affecting the study results and reliability
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Product no. B4429, Lot no. SLBK5235V
- Expiration date of the lot/batch: 30 April 2018
- Purity test date: na

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: no

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: activated sludge from a domestic waste water treatment plant
- Origin: sewage plant Balonfüred, Hungary
- Preparation of inoculum for exposure: The sludge was washed by centrifugation. The solid material was re-suspened in isotonic saline solution
by shaking and centrifuging. This procedure was repeated twice. An aliquot of the final sludge suspension was weighted, dried and the ratio of wet sludge to dry weight determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 5g dry material/L was mixed with mineral medium and then aerated under test conditions (for 6 days) until use. A pH adjustment of activated sludge inoculum was not performed.
- Laboratory culture: not applicable
- Method of cultivation: not applicable
- Storage conditions: not applicable
- Storage length: not applicable
- Pretreatment: Pre-conditioning consisted of aerating (2L/min) activated sludge (in mineral medium) for 6 days at the test temperature (20.1-21.9°C).
- Concentration of sludge: 5g/L
- Initial cell/biomass concentration: call count of approx. 10e7-10e8/L
- Water filtered: yes
- Type and size of filter used, if any: cotton and coarse filter paper
Duration of test (contact time):
28 d
Initial conc.:
33 mg/L
Based on:
test mat.
Remarks:
corresponds to 15 mg organic DOC/L
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: According to the OECD TG 301B (In solution b) CaCl2*2H2O was used and d) was immediately prepared before use without any additive).
- Additional substrate: none
- Solubilising agent (type and concentration if used): none
- Test temperature: 20.1 - 21.1 °C
- pH: approx. 7.58 (on day 28)
- pH adjusted: at study start to 7.38 (with 1N HCl)
- CEC (meq/100 g): no information available
- Aeration of dilution water: no
- Suspended solids concentration: approx. 25 mg/L
- Continuous darkness: yes
- Other: none

TEST SYSTEM
- Culturing apparatus: glass flasks (5000 mL)
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: aeration with CO2-free air at a rate of about 60 mL/min.
- Method used to create anaerobic conditions: not applicable
- Measuring equipment: The total carbon, inorganic carbon and dissolved organic carbon of the centrifuged samples were measured with Shimadzu Total Organic Carbon Analyzer (TOC-L CSH type).
- Test performed in closed vessels due to significant volatility of test substance: no
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: barium hydroxide adsorption bottles
- Other: none

SAMPLING
- Sampling frequency: on days 0, 2, 4, 6, 8, 11, 15, 20, 25, 28 and 29
- Sampling method: not applicable
- Sterility check if applicable: not applicable
- Sample storage before analysis: not applicable
- Other: none

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Abiotic sterile control: No (based on results of preliminary experiments)
- Toxicity control: Yes
- Other: none

STATISTICAL METHODS: according to OECD TG 301B
Reference substance:
benzoic acid, sodium salt
Test performance:
The reference item sodium benzoate was sufficiently degraded (>60 %) after 6 days, and to approx 72.5 % after 15 days of incubation, thus confirming the suitability of the used activated sludge inoculum.
In the toxicity control containing both, the test item and the reference item, a biodegradation of more than 25% was observed after 14 days of incubation. Thus, the test item can be assumed to be not inhibitory on the activated sludge microorganisms.
Key result
Parameter:
% degradation (CO2 evolution)
Value:
11.89
Sampling time:
28 d

In a study according to OECD TG 301B under GLP conditions, the substance was found to be not readily biodegradable.

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

The test item was investigated for its ready biodegradability in a study according to OECD TG 301B under GLP. The biodegradation was followed by CO2-evolution. As a reference item, sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

The biodegradation of the substance was approx. 11.89% after 28 days, while the reference item sodium benzoate was sufficiently degraded  (>60 %) after 6 days, and to approx 72.5 % after 15 days of incubation, confirming the suitability of the used activated sludge inoculum.

In the toxicity control containing both, the test item and the reference item, a biodegradation of 27.25% was observed after 14 days of incubation. Thus, the test item can be assumed to be not inhibitory on the activated sludge microorganisms.

In conclusion, the substance was not readily biodegradable.

Description of key information

In a study according to OECD TG 301B under GLP, the substance was found to be not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information

Categories Display