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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Justification for type of information:
The read across approach is detailed into the document attached to the IUCLID section 13.
Reason / purpose:
read-across source
Related information:
Composition 1
Reference:
Composition 0
Qualifier:
according to
Guideline:
other: DIN 38 409
GLP compliance:
yes
Test material information:
Composition 1
Specific details on test material used for the study:
Due to insufficient solubility, no stock solution was used.
The test specimen was weighed directly into the container batches.
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge: municipal wastewater treatment plant Frankfurt/M-Sindlingen.
- Collected sludge: 25 mg/l dry weight.
- Pre-treatment: 7 days under stirring, in mineral nutrient solution.
Duration of test (contact time):
28 d
Initial conc.:
137 mg/L
Based on:
test mat.
Initial conc.:
335 mg/L
Based on:
COD
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: the composition of the reaction medium corresponded to the medium described in the EEC Directive 84/449.
- Test temperature: 22 ± 1 °C
- Vessels: Erlenmeyer flasks.
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
28 d
Details on results:
Test item resulted to be not biodegradable under the conditions of the experiment.
Oxygen consumption - test item
Day Determination 1 Determination 1 Determination 1 Mean decomposition (%)
Theoretical oxygen Theoretical oxygen Theoretical oxygen
mg/l (O2) 350.95 mg/l (O2) 350.95 mg/l (O2) 350.95
Oxygen consumption Decomposition (%) Oxygen consumption Decomposition (%) Oxygen consumption Decomposition (%)
3 0.0 0 0.00 0 - - 0
7 1..3 0 0.00 0 - - 0
10 2.0 1 0.00 0 - - 1
14 3.6 1 0.00 0 - - 1
17 4.6 0 0.00 0 - - 0
21 5.7 0 0.00 0 - - 0
24 5.9 0 0.00 0 - - 0
28 6.9 0 0.00 0 - - 0

The third determination was not used for the evaluation because of occurrence of error.

Oxygen consumption - blank

Day Determination 1 Determination 2 Determination 3 Mean mg/l (O2)
Oxygen consumption mg/l (O2)
3 0.0 0.0 0.0 0.0
7 0.0 0.0 0.0 0.0
10 0.0 0.0 0.0 0.0
14 1.8 0.0 0.0 0.6
17 6.0 0.0 4.4 3.5
21 7.5 0.0 7.8 5.1
24 9.9 0.0 11.3 7.1
28 9.9 0.0 11.3 7.1
Interpretation of results:
not readily biodegradable
Conclusions:
Not ready biodegradable
Executive summary:

The determination of the test item chemical oxygen demand (COD) was performed according to DIN guideline 38 409. Due to insufficient solubility, no stock solution was used; the test substance was weighed directly into the container batches. Organisms were collected from municipal wastewater treatment plant Frankfurt/M-Sindlingen. No biodegreadation was observed over a period of 28 days, thus, the test item resulted to be not biodegradable under the conditions of the experiment.

Conclusion

Not ready biodegradable

Description of key information

Nor readily biodegradable.

Key value for chemical safety assessment

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

Additional information

The substance is a fluorescent brightener, benzoxazolyl stilbene derivative. It is not expected to be ready biodegradable because of its chemical structure and the specific function. Commonly, fluorescent brighteners undergo a primary transformation, i.e. discolourization due to the interrupting the conjugation. Nevertheless, the degradation process involves more steps and take more time.

An experiment on the determination of the chemical oxygen demand (COD) is available on the analogous Similar Substance 01; the read across approach can be considered as suitable and appropriate to investigate the biodegradabiity potential of Fluorescent Brightener 002 (the read across approach is detailed in the document attached to the IUCLID section 13).

The experiment the study was performed according to DIN guideline 38 409. No biodegreadation was observed over a period of 28 days, confirming the expectation that the substance is not readly biodegradable.