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Biodegradation in water: screening tests

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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
according to guideline
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Temperature range was 19.4 – 21.5 °C instead of 20.0 – 24.0 °C. As degradation of the positive control was in the normal range, this is considered as uncritical concerning the outcome of the study.
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): ESN (Stadtentsorgung Neustadt), Im Altenschemel, NW-Lachen-Speyerdorf (date of collection: 06.10.17 batch no: 20171006)
- Laboratory culture:
- Method of cultivation:
- Storage conditions: in test medium under aeration
- Storage length: 3 days
- Preparation of inoculum for exposure:
- Pretreatment: filtration, 2x washing (tap water), wash and re-suspension in test medium
- Concentration of sludge: 4520 mg/L dw
- Initial cell/biomass concentration:
- Water filtered: yes/no
- Type and size of filter used, if any:
Duration of test (contact time):
28 d
Initial conc.:
27.5 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
- Composition of medium: standard test medium
- Additional substrate: -
- Solubilising agent (type and concentration if used): -
- Test temperature: 19.4 - 21.5 °C
- pH: test flasks: 7.4
- pH adjusted: no
- CEC (meq/100 g):
- Aeration of dilution water:
- Suspended solids concentration: 25 mg/L
- Continuous darkness: yes/no
- Other:

- Culturing apparatus: 2 L Flask
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: aeration with purified (by activated charcoal), CO2-scrubbed, moistened air
- Method used to create anaerobic conditions: -
- Measuring equipment: Carbon analyser TOC multi N/C 2100S, Analytik Jena
- 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: NaOH (0.25 M)
- Other:

- Sampling frequency: day 0, 3, 6, 8, 10, 14, 17, 23 and 29
- Sampling method: 1 mL from scrubber flask
- Sterility check if applicable:
- Sample storage before analysis:
- Other:

- Inoculum blank: 2
- Abiotic sterile control: 1
- Toxicity control: 1
- Other: 2 system blanks

Reference substance:
Key result
% degradation (CO2 evolution)
Sampling time:
28 d
Details on results:
abiotic control (28 d): 5.9 %
toxicity control (28 d): 76.3 %
Results with reference substance:
84.9 % after 28 d
Validity criteria fulfilled:
Interpretation of results:
readily biodegradable
As the test substance is a multiconstituent substance, it is considered to be similar to a mixture in the sense of the evalaution of the OECD 301 screening study. Therefore, the pass level of 60 % after 28 days is fulfilled and the substance is considered to be readily biodegradable.
Executive summary:

The test item N-(hydroxymethyl) stearamide was tested using a concentration of nominally 20 mg organic carbon/L (corresponding to 27.5 mg N-(hydroxymethyl) stearamide/L) in test medium following OECD 301B and EU-Method C.4-C.

Aniline was chosen as positive control.

Activated sludge was used as inoculum (concentration in the test 25.0 mg dry matter/L). The test was left running for 28 days.

All validity criteria were met. Degradation of the positive control was 69 % after 10 days.

The following data were determined for the test item N-(hydroxymethyl) stearamide:

10-day-window:                                                                                    days 4 -14

degradation at the end of 10-day-window                                                 45 %

degradation at the end of the test                                                               64 %

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

respectively 60 % at the end of the test for mixtures

As the test item is a multiconstituent substance it is considered to be similar to a mixture. Thus, the 10-day-window is not applicable, and the test substance is considered as readily biodegradable following OECD 301B and EU C.4-C respectively.

Description of key information

The test substance is examined in an OECD 301 screening study for readily biodegradability. As the substance is a multi-constituent substance with structurally similar constituents, the 10 -day-window condition is skipped. After 28 days more than 60 % degradation are observed indicating a readily biodegradability of the test substance.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:

Additional information