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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:
2013-06-06 to 2013-07-11
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
GLP study
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
adopted 1992-07-17
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
TEST MATERIAL
- Lot/batch No.of test material: 11/LE/016 K1
- Expiration date of the lot/batch: 2014-03-13
- Purity test date: 2013-03-131
- Purity:


STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Tightly closed, protected from moisture at room temperature
- Stability under test conditions: stable
- Solubility and stability of the test substance in the solvent/vehicle: <0.1% (water solubility)

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Municipal sewage treatment plant, 31137 Hildesheim, Germany
- Pretreatment:
The activated sludge was washed twice with chlorine free tap water. After the second washing the settled sludge was resuspended in mineral salts medium and was maintained in an aerobic condition by aeration for 2 hours. Thereafter the sludge was homogenized with a blender. The supernatant was decanted and maintained in an aerobic condition by aeration with CO2 free air until test start. 10 mL/L of this mixture were used to initiate inoculation.

Duration of test (contact time):
28 d
Initial conc.:
25 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST METHOD
Duration: 28 d
Application: Once at test start
Test vessels: 500 mL, brown glass
Volume of the test medium : 250 mL
Test medium: Mineral salts medium acc. to OECD 301 F / Manometric Respirometry Test
Test temperature: Nominal 20-24°C, actual measured 19.5 - 20°C
Dispersion treatment: Continuous stirring
Photoperiod: Dark, in an incubator
Reference substance:
benzoic acid, sodium salt
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
7 d
Parameter:
% degradation (O2 consumption)
Value:
2
Sampling time:
14 d
Remarks on result:
other: Replicate 1: 4% Replicate 2: 0%
Parameter:
% degradation (O2 consumption)
Value:
4.5
Sampling time:
21 d
Remarks on result:
other: Replicate 1: 9% Replicate 2: 0%
Key result
Parameter:
% degradation (O2 consumption)
Value:
8
Sampling time:
28 d
Remarks on result:
other: Replicate 1: 16% Replicate 2: 0%
Details on results:
The biodegradation of the test item is shown graphically in Figure 1 in comparison to the readily degradable functional control and the toxicity control. The first test item replicate reached the 10% level (beginning of degradation) after an adaptation phase on day 23 and at test end the biodegradation reached 16%. The 2nd replicate did not reach the 10% level until test end. The biodegradation of the 2nf replicate remained at 0%. Both test item replicates did not reach the 60% pass level within 28 days.
Results with reference substance:

To check the activity of the test system, sodium benzoate was used as functional control. The percentage degradation of the functional control reached the pass level of 60 % within 3 days and a biodegradation of 100 % after 13 days. In the toxicity control containing both test and reference item a biodegradation of 50 % was reached after 14 days. After 28 days a biodegradation of 55 % was determined. The biodegradation of the reference item was not inhibited by the test item in the toxicity control.

Biodegradation of the test item in comparison to the functional control and toxicity control:

  Biodegradation
            Study Day [d]
   15  21  28
 Test Item, 1st Replicate 0  4  9  16
 Test Item, 2nd Replicate 0  0  0  0
 Functional Control 93  100  100  100
 Toxicity Control  45  50  52  55
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
Under the test conditions the test item is not readily biodegradable in the 10-day-window and within 28 days.
Executive summary:

Under the test conditions the test item is not readily biodegradable in the 10-day-window and within 28 days.

Description of key information

The test material was not readily biodegradable in a manometric respirometry test according to OECD 301 F.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information