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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:
experimental study
Adequacy of study:
key study
Study period:
from 1990-09-12 to 1990-10-10
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods
Qualifier:
according to guideline
Guideline:
other: Biologische Abbaubarkeit - Respirometer test. The test was performed in accordance with regulation (EC) 79/831 EWG Annex V. Modifications were done in accordance with EEC Directive 79/831 (Painter).
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: 10 L laboratory (Wupperverband)
- Sampling date: 12.09.1990
- Pretreatment: no
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Procedure:
The test item was dissolved and suspendeed, respectively, in non-mineralic medium. Afterwards non-adapted activated sludge was added. After 28 days exposure (contact time) the oxygen consumption was measured in a closed respirometer (at a temperature of 20 ± 1 °C) automatically. The biological degradation was determined as the oxygen consumption (%) based on the theoretical oxygen demand (TOD) and CSB (corrected by the oxygen demand of the blank), respectively.

Others:
- Amount of substance: 100 mg/L
- TOD (Theoretical oxygen demand): 2646 mg/L
- Concentration of inoculum: 30 mg/L
Reference substance:
aniline
Key result
Parameter:
% degradation (O2 consumption)
Value:
43
Sampling time:
28 d
Details on results:
Time (days) / oxygen consumption mg/L of test item; blank / biodegradation (%)
- 2 / 10; 7 / 1
- 6 /93; 14 / 30
- 8 / 110; 18 / 35
- 12 / 129; 22 / 40
- 14 / 133; 23 / 42
- 16 / 136; 24 / 42
- 20 / 142; 29 / 43
- 22 / 145; 32 / 43
- 26 / 147; 33 / 43
- 28 / 148; 33 / 43

The theoretical oxygen demand of NO3- was used as reference for the calculation of the biodegradation.
Results with reference substance:
Aniline showed 61 % biodegradation after 28 days.

Based on the results with the reference substance the study result was considered valid.

Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable, fulfilling specific criteria
Conclusions:
The test item was biodegraded 43 % at day 28 in the test using a closed respirometer. The test item was considered inherently biodegradable.
Executive summary:

A ready biodegradability test with the test item was performed which allows the biodegradability to be measured in an aerobic aqueous medium. The ready biodegradability was determined using a closed respirometer according to test method outlined in EEC Directive 79/831. The test item was biodegraded 43 % at day 28. Therefore, the test substance was considered inherently biodegradable.

Description of key information

The test item was biodegraded 43 % at day 28 in the test using a closed respirometer. The test item was considered to be inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable, fulfilling specific criteria
Type of water:
freshwater

Additional information

A ready biodegradability test with the test item was performed which allows the biodegradability to be measured in an aerobic aqueous medium. The ready biodegradability was determined using a closed respirometer according to test method outlined in EEC Directive 79/831. The test item was biodegraded 43 % at day 28. Therefore, the test substance was considered to be inherently biodegradable.