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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 1990-05-04 to 1990-08-27
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Version / remarks:
1981
Deviations:
no
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Type: The inoculum was a composite made from equal parts of the total effluent of a sludge plant and the reflux of an activated sludge plant, with the addition of a suspension of standard soil.
- Source of inoculum/activated sludge: Effluent of municipal sewage treatment plant of the city of Neuenfeld (ex WTTP), Hamburg (Germany)
- Method of cultivation: Aerobic and dark conditions at 20 °C
- Preparation of inoculum for exposure: The inoculum were filtered and mixed with standard soil (a mixture of humus and loamy soil from the region of Speyer, Germany).
- Pretreatment: not performed
- Water filtered: Yes




Duration of test (contact time):
28 d
Initial conc.:
8.57 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: Mineral medium according to OECD 301 D
- Solubilising agent: no
- Test temperature: 20 +/- 1 °C
- Aeration of dilution water: yes
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Flasks according to OECD 301 D
- Number of culture flasks/concentration: 4
- Measuring equipment: The oxygen content in the aqueous test solutions was electrochemically determined by the OXI 530 with a TriOX EO 200-electrode (WTW). Calibration was effected according to the supplier's prescriptions with the "OxiCal"-calibration vessel, and for the Oxygen-measurement within the BOD-bottles the funnel and stirring option TS 19 and RZ 90 were used (stirrer speed during the measurements: 1100 rpm).
- Test performed in closed vessels: yes

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes. Inoculum and mineral medium without test substance
- Procedure control: yes. Performed with the reference material sodium-n-dodecylsulfate
- Toxicity control: yes
Reference substance:
other: Sodium-n-dodecylsulfate
Preliminary study:
Not performed
Test performance:
The test was considered valid. In the parallel tests with the reference material sodium-n-dodecylsulfate, a degradation of 61.2 was determined after 15 days and a degradation of 72.8 % was reached after 28 days. In addition, an inhibitory effect on the biodegradation of the test substance was not determined.
Key result
Parameter:
% degradation (O2 consumption)
Value:
2.3
Sampling time:
28 d
Details on results:
Within the study period of 28 days, a degradation of 2.3 % was determined for the test substance, therefore the test substance is to be classified as being „not readily biodegradable".
Results with reference substance:
The reference substance was biodegraded 43.7 % after 5 days, 61.2 % after 15 days and 72.8 % after 28 days.
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The ready biodegradability of the test item was determined according to OECD 301 D. Within the study period of 28 days, a degradation of 2.3 % was determined for the test substance. Therefore, the test substance is considered to be not readily biodegradable.
Executive summary:

The ready biodegradability of the test substance was investigated according to the OECD guideline 301 D: Closed bottle test (1992). The biodegradation of the test substance was followed by exposing it in a mineral medium, prepared according to the prescriptions of the Guideline. The inoculum was a composite made from equal parts of the total effluent of a sludge plant and the reflux of an activated sludge plant in Neuenfelde in Hamburg (Germany), with the addition of a suspension of standard soil. The oxygen depletion was measured after 5, 15 and 28 days. Control- and blank-series without test substance were run simultaneously and the effectiveness of the inoculum was confirmed in a third series with sodium-n-dodecylsulfate as reference substance. The reference substance attained a degradation of 61.2 after 15 days and 72.8 % biodegradation level (greater than 60 % degradation) within 28 days. The validity criteria were met. The theoretical oxygen demand (TOD) was calculated to be TOD = 2.95 mg O2/mg active substance. In addition, it was established that the test substance has no inhibiting effect on the biological degradation of the reference substance. Within the study period of 28 days, a degradation of 2.3 % was determined for the test substance. Therefore, the test substance is considered to be not readily biodegradable.

Description of key information

The ready biodegradability of the test item was determined according to OECD 301 D (reference 5.2.1-1). Within the study period of 28 days, a degradation of 2.3 % was determined for the test substance. Therefore, the test substance is considered 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

The ready biodegradability of the test substance was investigated according to the OECD guideline 301 D: Closed bottle test (1992). The biodegradation of the test substance was followed by exposing it in a mineral medium, prepared according to the prescriptions of the Guideline. The inoculum was a composite made from equal parts of the total effluent of a sludge plant and the reflux of an activated sludge plant in Neuenfelde in Hamburg (Germany), with the addition of a suspension of standard soil. The oxygen depletion was measured after 5, 15 and 28 days. Control- and blank-series without test substance were run simultaneously and the effectiveness of the inoculum was confirmed in a third series with sodium-n-dodecylsulfate as reference substance. The reference substance attained a degradation of 61.2 after 15 days and 72.8 % biodegradation level (greater than 60 % degradation) within 28 days. The validity criteria were met. The theoretical oxygen demand (TOD) was calculated to be TOD = 2.95 mg O2/mg active substance. In addition, it was established that the test substance has no inhibiting effect on the biological degradation of the reference substance. Within the study period of 28 days, a degradation of 2.3 % was determined for the test substance. Therefore, the test substance is considered to be not readily biodegradable.

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