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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:
2007-03-26 to 2007-04-25
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP conform screening test. No deviations.
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): wastewater treatment plant of Mannheim
- Concentration of sludge: 30 mg dw/L
Duration of test (contact time):
28 d
Initial conc.:
16 mg/L
Based on:
test mat.
Parameter:
% degradation (CO2 evolution)
Value:
>= 10 - <= 20
Sampling time:
28 d
Details on results:
46 % biodegradation of inhibition control (test item + reference item).
Results with reference substance:
76 % after 14 days
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1996
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study performed under GLP
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: Biodegradability study of Chemical Substances by Microorganisms; Testing Methods relating New Chemical Substances (Kanpogyo No. 5, Yakuhatsu No. 615, 49 Kikyoku No. 392, July 13, 1974
Deviations:
no
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
mixture of sewage, soil and natural water
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Sludge from four sewage treatment plants, surface water and shoreline soil (which was in contact with the atmosphere) from three rivers, one lake and two marine sites was collected. 500 mL of each of the filtrate of the activated sludge collected from the sites described above and 5 L of the filtrate of the old activated sludge used for the study until that time was mixed to obtain 10 L of mixture. The pH was adjusted to 7.0+/-1.0 and aerated in a culture tank.
- Method of cultivation: Approximately 30 minutes after aeration ceased ,approximately 1/3 of the total volume was removed and replace with dechlorinated water. The mixture was re-aerated and synthetic sewage added so that the concentation of supernatant exchange fluid was set to 0.1%.
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
TEST CONDITIONS
- Test temperature: 25+/-1°C
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes
- Other:


TEST SYSTEM
- Culturing apparatus: Closed system oxygen consumption measuring apparatus
- Number of culture flasks/concentration: 3 vessels used for test material + activated sludge
- Details of trap for CO2 and volatile organics if used: Soda lime No. 1 used for carbon dioxide gas absorbent


SAMPLING
- Sampling frequency: Measured after 28 days


Reference substance:
aniline
Parameter:
% degradation (test mat. analysis)
Value:
0
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
28 d
Results with reference substance:
Percentage degradation of aniline after 7 and 14 days obtained by BOD were 64 % and 76 % respectively, confirming the validity of the study.
Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
1988/09/22 to1988/10/22
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study not performed under GLP. Deviations to the updated OECD-Guideline (adopted 1992): Test solution volume reduced. The CO2 formed by biodegradation was absorbed. An emulsifier was used due to poor solubility of the test substance.
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
yes
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 from activated sludge of the sewage treatment plant of CH-4153 reinach
- Preparation of inoculum for exposure: The preparation was carried out according to the method described in the guideline.
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: in accordance to the guideline
- Test temperature: 22 +/- 2 °C
- Aeration of dilution water: 25 mL/min free of carbon dioxide

TEST SYSTEM
- Culturing apparatus: 2 Liter flasks equipped with gas inlet and magnetic stirrer.
- Method used to create aerobic conditions: 24 hours aeration of minaeral solution in test vessel
- Details of trap for CO2 and volatile organics if used: Determination of the initial COa of the 0.05 N sodium hydroxide and the CO2, absorbed in the absorbers filled with 200 mL 0.05 N sodium hvdroxide on the davs 5, 11, 18, 22, 27 and 28.

CONTROL AND BLANK SYSTEM
Blank: water
Blank + vehicle: water containing 0.5 mL of nonylphenol 10E05P0


Reference substance:
aniline
Remarks:
20 mg/L
Parameter:
% degradation (CO2 evolution)
Value:
10
Sampling time:
28 d
Remarks on result:
other: 10 mg/L test substance concentration
Parameter:
% degradation (CO2 evolution)
Value:
2
Sampling time:
28 d
Remarks on result:
other: 20 mg/L test substance concentration
Details on results:
Theoretical carbon dioxide formation:
Reference substance: 20 mg/L = 85.061 mg CO2/1.5 L.
Test substance: 10 mg/L = 35.54 mg CO2/1.5 L.
Test substance: 20 mg/L = 71.07 mg CO2/1.5 L.
Results with reference substance:
94.4 % in 28 days
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 v5.12.1

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 v5.12.1 BOD 28 days MITI (OECD 301C) v.10.14
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:
0
Sampling time:
28 d
Remarks on result:
not readily biodegradable based on QSAR/QSPR prediction

Concomitant predictions :

Not ready degradable

Primary Half Life = 9m 26d

Ultimate Half Life = more than 10 years

- Predicted value (model result): O2 -consumption (BOD) = 0.00 ± 2.92E-3

No relevant metabolites.

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). Poorly biodegradable.

Key value for chemical safety assessment

Additional information

For the assessment of the biodegradation of the test item three OECD 301 studies are available.

A study according to OECD 301 B conducted as screening test with test substance concentration of 16 mg/L revealed a biodegradation rate of >= 10 <= 20% (BASF SE 2007).

A second study according to OECD 301 C revealed a biodegradation rate of 0% after 28 days (MITI, Japan)

A supporting study according to OECD 301 B conducted with a test substance concentration of 10 and 20 mg/L revealed a biodegradation rate of 2 to 10%, respectively (Ciba-Geigy Ltd. 1988).

Furthermore, Catalogic v5.12.1, CATALOGIC 301C v.10.14 was used to identify possible degradation products. The compound is within the applicability domain of the model (parameter domain, structural fragment domain and metabolic domain) and revealed a predicted BOD of 0% after 28d. No relevant metabolites could be identified.

In summary, the compound is not readily biodegradable, no relevant metabolites could be identified.