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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1984-06-08 to 1984-07-06
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP study. Guideline from 1981. Deviation to the updated OECD Guideline (adopted 1992): Volume of suspension; 1.5 liter instead of 3.0 liter.
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
yes
Remarks:
Non-GLP study. Guideline from 1981. Deviation to the updated OECD Guideline (adopted 1992): Volume of suspension; 1.5 liter instead of 3.0 liter.
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Bacteria collected fron activated sludge of the sewage treatment plant of CH-4310 Rheinfelden on 07/06/1934
Duration of test (contact time):
28 d
Initial conc.:
10 mg/L
Based on:
test mat.
Initial conc.:
20 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: according to the guideline
- Test temperature: 22 °C +/- 2
- Aeration of dilution water: Approx. 50 mL air/min free of carbon dioxide

TEST SYSTEM
- Culturing apparatus: 2 liters flasks equipped with gas inlet and magnetic stirrer
- Details of trap for CO2 and volatile organics if used: Titration of the CO2, absorbed in the absorbers filled with 0.025 N Bariun hydroxide on the days 4 / 7 / 10 / 14 / 19 / 24 / 27 and 28.

CONTROL AND BLANK SYSTEM
- Reference substance 20 mg/L
Reference substance:
aniline
Parameter:
% degradation (CO2 evolution)
Value:
6
Sampling time:
28 d
Remarks on result:
other: 10 mg/L
Parameter:
% degradation (CO2 evolution)
Value:
1
Sampling time:
28 d
Remarks on result:
other: 20 mg/L
Details on results:
The test item is not biodegradable in this test.
Results with reference substance:
The biodegradation was determined to be 101 % in 28 days at a concentration at 20 mg/L.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Justification for type of information:
1. SOFTWARE
OASIS Catalogic v5.11.19

2. MODEL (incl. version number)
CATALOGIC 301C v.09.13

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See section 'Test Material'.

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF.

5. APPLICABILITY DOMAIN
See attached QPRF.

6. ADEQUACY OF THE RESULT
- The model is scientifically valid (see attached QMRF).
- The model estimates the biodegradability of a substance and identifies its degradation betabolites. Screening information on the ready biodegradability is required for substances manufactured or imported in quantities of 1 t/y or more. Depending on the results, further information may be required for substances manufactured or imported in quantities of 100 t/y or more (simulation testing on ultimate degradation in surface water/soil/sediment). Column 2 of REACH Annex VII provides exemptions for conducting the study. It does not need to be conducted if the substance is inorganic. According to column 2 of REACH Annex IX, testing is not required if the substance is highly insoluble in water, or the substance is readily biodegradable.
- See attached QPRF for reliability assessment.
Principles of method if other than guideline:
Estimation of ready biodegradation in water using CATALOGIC v5.11.19 BOD 28 days MITI (OECD 301C) v09.13
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: Model calculation
Duration of test (contact time):
28 d
Parameter:
% degradation (O2 consumption)
Value:
1
Sampling time:
28 d
Remarks on result:
not readily biodegradable based on QSAR/QSPR prediction

- Concomitant predictions :

Not readily biodegradable

Primary Half Life = 9.92 days

Ultimate Half Life = 3y 7m 2d

- Predicted value (model result): O2 -consumption (BOD) = 0.01 ± 4.62E-3

Interpretation of results:
not readily biodegradable
Remarks:
parent substance
Conclusions:
The substance is not readily biodegradable.

Description of key information

Not readily biodegradable (according to OECD criteria).

Key value for chemical safety assessment

Additional information

The ready biodegradability of the test item was assessed over a 28 day period by the modified Sturm test (OECD 301B). The nominal test concentrations were 10 and 20 mg a.s./L. The test material attained up to 6 and 1 % biodegradation after 28 days whereas the positive control substance (Aniline) was 101 % degraded 28 days. These results indicate that the test item cannot be classified readily biodegradable under conditions of the test.

Additional QSAR calculations with Catalogic v5.11.19, Catalogic 301C v09.13 revealed a degradation of 1% after 28d. The main metabolite was 3-(3,5-ditert-butyl-4-hydroxy-phenyl)propanoic acid.

The test substance was found to be poorly biodegradable in an OECD 301B study. It is assumed that the results of further simulation studies would not reveal any different findings. Therefore, further simulation studies in water/sediment and soil are not provided.