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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 guideline.
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
adopted 12 May 1981
Deviations:
yes
Remarks:
See "Principles of method if other than guideline"
Principles of method if other than guideline:
The volume of the test solution was reduced from 3.0 L to 1.5 L.
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Sewage treatment plant of CH-4310 Rheinfelden on 07/06/1984
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
- Test temperature: 22 ± 2 °C
- Aeration of dilution water: Approx. 50 ml/min free of carbon dioxide.
- Other: The test substance was not dissolved in the test medium. 10 mg/L test substance are equivalent to 7.099 mg/L organic carbon/L.

TEST SYSTEM
- Culturing apparatus: 2 L flasks equipped with gas inlet and magnetic stirrer.
- Number of culture flasks/concentration: 1
- Details of trap for CO2 and volatile organics if used: absorbers filled with 0.025 N Barium hydroxide
- Measuring: Titration of CO2

SAMPLING
- Sampling frequency: days 4, 7, 10, 14, 19, 24, 27, and 28

CONTROL AND BLANK SYSTEM
- Inoculum blank: none
- Toxicity control: Aniline
Parameter:
% degradation (CO2 evolution)
Value:
7
Sampling time:
28 d
Remarks on result:
other: Cumulative result for 10 mg/L test stubstanace
Parameter:
% degradation (CO2 evolution)
Value:
2
Sampling time:
28 d
Remarks on result:
other: Cumulative result for 20 mg/L test substance
Details on results:
The biodegradation was calculated on the basis of the theoretical carbon content of the test substance and the cumulative quantities of carbon dioxide determined on the days of measurements. For the calculations the formula given in the guideline was used. Theoretical carbon dioxide formation:
reference substance (20 mg/L) = 85.061 mg CO2/1.5 L
test substance (10 mg/L) = 39.03 mg CO2/1.5 L
test substance (20 mg/L = 78.07 mg CO2/1.5 L
Results with reference substance:
The biodegradation was calculated as: 101 % in 28 d (20 mg/L Aniline)
Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
1990-05-31 to 1990-06-29
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP study.
Qualifier:
according to
Guideline:
OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)
Version / remarks:
adopted 12 May 1981
Deviations:
yes
Remarks:
See "Principles of method if other than guideline"
Principles of method if other than guideline:
HPLC was used, therefore the initial test concentration was reduced to 8.6 mg/L (nominal). Test duration was 29 d.
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Duration of test (contact time):
29 d
Initial conc.:
8.6 mg/L
Based on:
test mat.
Parameter:
% degradation (test mat. analysis)
Value:
-7
Sampling time:
1 d
Remarks on result:
other: Mean value. Negative values are within the variation of the method.
Parameter:
% degradation (test mat. analysis)
Value:
-24
Sampling time:
5 d
Remarks on result:
other: Mean value. Negative values are within the variation of the method.
Parameter:
% degradation (test mat. analysis)
Value:
-9
Sampling time:
11 d
Remarks on result:
other: Mean value. Negative values are within the variation of the method.
Parameter:
% degradation (test mat. analysis)
Value:
7
Sampling time:
22 d
Remarks on result:
other: Mean value.
Parameter:
% degradation (test mat. analysis)
Value:
11
Sampling time:
29 d
Remarks on result:
other: Mean value.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
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
Key result
Parameter:
% degradation (O2 consumption)
Value:
3
Sampling time:
28 d
Remarks on result:
not readily biodegradable based on QSAR/QSPR prediction

- Concomitant predictions :

Not readily biodegradable

Primary Half Life = 12.01 days

Ultimate Half Life = 2y 0m 28d

- Predicted value (model result): O2 -consumption (BOD) = 0.03 ± 4.93E-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 7 and 2 % biodegradation after 28 days whereas the positive control substance (Aniline) was  101 % in 28 d. These results indicate that the test item cannot be classified readily biodegradable under conditions of the test. The biodegradability was also determined in a Modified Zahn-Wellens Test (OECD 302 B) by measuring the fate of the test substance by specific analysis. The biodegradation calculated as percentage of measured test substance concentration related to initial concentration determined was: 13 % and 8 % (duplicate determination; mean value 11%). The test substance was not inherently biodegradable in this test when measured by specific analysis.

Additional QSAR calculations with Catalogic v5.11.19, Catalogic 301C v09.13 revealed a degradation of 3% 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 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.