Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

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

Data source

Reference Type:
study report

Materials and methods

Test guideline
according to guideline
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
potential deviations would be documented in amendments
GLP compliance:
yes (incl. QA statement)
GLP-Conformity All procedures according to the principles of GLP (Chemikaliengesetz §19a and §19b and annexes 1 and 2 from 28. Aug. 2013, published in Federal Law Gazette, Germany (BGBl) No. 55/2013 as of 06. Sep. 2013, and further revisions).

Test material

Constituent 1
Test material form:
liquid: viscous
Details on test material:
- State of aggregation: contains polymer which is not soluble after dessication
- Particle size distribution: not appropriate (liquid)
- Mass median aerodynamic diameter (MMAD): not appropriate
- Geometric standard deviation (GSD): not appropriate
- Shape of particles: not appropriate
- Surface area of particles: not appropriate
- Crystal structure: not appropriate
- Coating: not appropriate
- Surface properties: surface tension see appropriate section of IUCLID
- Density: see appropriate section of IUCLID
- Moisture content: see above
- Residual solvent: see above
- Activation: not appropriate
- Stabilisation: not required as long as treated properly and instructions of manufacturer are followed
Specific details on test material used for the study:
- Source and lot/batch No.of test material: The test material is representative of the registered substance
- Expiration date of the lot/batch: not relevant
- Purity test date: not relevant

- Storage condition of test material: at room temperature in the dark
- Stability under test conditions: stable
- Solubility and stability of the test substance in the solvent/vehicle: soluble

- Treatment of test material prior to testing: none
- Preliminary purification step (if any): none

Study design

Oxygen conditions:
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Activated sludge from a biologic sewage treatment plant was used as inoculum. The chosen plant is treating mostly domestic sewage.
The sludge was collected from the activation basin of the sewage treatment plant Edenkoben on 23. Feb. 2018, batch no: 20180223.
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 3980 mg of sus-pended solids/L.
Duration of test (contact time):
28 d
Details on study design:
This study was performed in order to evaluate aerobic elimination and degradation potential in a test for ready biodegradability, using a test item concentration of nominally 20 mg organic carbon/L (corresponding to 95.6 mg test item).
The test item in a mineral medium was inoculated and incubated under aerobic conditions in the dark. The amount of DOC in the test solution due to the inoculum was kept as low as possible compared with the amount of organic carbon due to the test item. Allowance was made for the endogenous activity of the inoculum by running parallel blanks with inoculum but without test item. A positive control was run in parallel to check the operation of the procedures. Degradation was followed by determining the carbon dioxide produced. Measurements were taken at sufficiently frequent intervals to allow the identification of the beginning and end of biodegradation.
The test lasted for 28 days.

Test performance
The test vessels were aerated with purified (by activated charcoal), CO2-scrubbed, moistened air. The scrubbing of carbon dioxide is achieved by bubbling the purified air through a flask containing 1.5 M NaOH. To control the absence of CO2, the air is 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.

Instruments and Devices
The following instruments and devices were used.
• Data logger for temperature
• Analytical scales
• Adjustable pipettes with one-way tips
• Carbon analyser
• pH-meter
• Heating chamber
• Standard laboratory equipment
Reference substance
Reference substance:
positive control

Results and discussion

% Degradation
Key result
% degradation (CO2 evolution)
Sampling time:
28 d
Details on results:
2 % anaerobic degradation observed

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
not readily biodegradable
The aerobic ready biodegradability of the test item was determined in the CO2 Evolution Test following OECD 301B resp. EU C.4-C. In very dilute domestic sludge, degradation of the test item was lower (26 %) than the pass level (60 %), and the substance is considered as not readily biodegradable, but as no plateau level was reached, futher degradation is expected.
Executive summary:

The aerobic ready biodegradability of the test item was determined in the CO2 Evolution Test following OECD 301B resp. EU C.4-C. Degradation behaviour of positive control and toxicity control was normal. Abiotic degradation reached 2 %. Both replicates of the test item showed very good correspondence. The test item was not toxic towards the inoculum at the test concentration.

As degradation missed 60 % within 28 days, the test item is considered as not readily biodegradable within 28 days. However, at the end of the test no plateau of degradation was reached yet, indicating that further biodegradation is possible.

No observations were made which might cause doubts concerning the validity of the study outcome.