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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:
from 31 October 2001 to 2 January 2002
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
other: ISO 14593 (Water quality – Evaluation of the ultimate aerobic biodegradability of organic compounds in an aqueous medium – Method by analysis of inorganic carbon in sealed vessels)
Deviations:
yes
Remarks:
: temperature was below 22 (± 2) °C specified in the guideline on day 0 (19.5 °C) and day 4 (19.7 °C)
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Qualifier:
equivalent or similar to
Guideline:
EPA OPPTS 835.3120 (Sealed Vessel Carbon Dioxide Production Test)
Principles of method if other than guideline:
Conditions employed (mineral medium composition, activated sludge inoculum density and test substance concentration) are equivalent to those represented by the OECD 301 series (ready biodegradability). The test is equivalent to the OECD 301 B test.
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Burley Menston sewage treatment works (Yorkshire Water)
- Suspended solids concentration: 5.632 g solids/L
Duration of test (contact time):
28 d
Initial conc.:
10 mg/L
Based on:
other: TOC
Parameter followed for biodegradation estimation:
inorg. C analysis
Details on study design:
TEST CONDITIONS
- Composition of medium: Synthetic mineral salts medium containing 10 mL/L of solution a) and 1 mL/L each of solutions b), c) and d):
a) KH2PO4 (8.5 g/L), K2HPO4 (21.7 g/L), Na2HPO4.2(H2O) (33.4 g/L), NH4Cl (0.5 g/L)
b) CaCl2.2H2O (36.4 g/L)
c) MgSO4.7H2O (22.5 g/L)
d) FeCl3.6H2O (0.2 g/L)
- Test temperature: 20.9 - 22.2 °C (apart from the first day (19.5 °C) and fourth day (19.7 °C)); measured continuously
- pH: no data
- Suspended solids concentration: 4 mg/L (3 L medium inoculated with 2.13 mL activated sludge)
- Continuously shaking (135 rpm)
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: 160 mL glass bottles
- Volume of test medium: 107 mL
- Liquid : headspace ratio: 2:1
- Number of culture flasks/concentration: 5 bottles/concentration
- Test performed in closed vessels: prevent absorbing/measuring of atmospheric CO2


SAMPLING
- Sampling frequency: once at the last day of the experiment (day 28) after adding NaHO solution
- Sampling method: 1000 µL samples (in triplicate) were taken from each vessel through the butyl rubber plugs using a gas-tight syringe; samples were directly injected to a Rosemount Dohrmann DC-80 TOC analyser


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (test medium + activated sludge) => 5 replicates (like test and reference substance)
- Abiotic sterile control: no
- Toxicity control: no
Reference substance:
benzoic acid, sodium salt
Remarks:
initial concentration based on TOC: 15 mg/L
Parameter:
% degradation (inorg. C analysis)
Value:
37
Sampling time:
28 d
Results with reference substance:
The mean final degradation of the reference substance sodium benzoate was 96%.

The test substance was degraded to 37% after 28 days. Thus, the substance is not readily biodegradable according to the OECD testing scheme. ISO does not recognise the concept of "ready" biodegradability, or the notion passing or failing a biodegradability assessment. However, the conditions employed are equivalent to those represented by the OECD 301 series ready biodegradability test methods.

Table 1: Biodegradation of Atmer 163 at day 28 as Percentage Theoretical IC Yield

Atmer 163

Reference substance: sodium benzoate

42%

97%

42%

95%

34%

95%

29%

95%

38%

96%

mean: 37%

mean: 96%

Interpretation of results:
other: Significant mineralisation occurred but degradation did not reach 60% and thus Atmer 163 would not qualify for classification as readily biodegradable.
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:
other: see 'Remark'
Remarks:
Validated QSAR model. Calculation for main component of Ethanol, 2,2'-iminobis-, N-(C13-15-branched and linear alkyl) derivs., CAS 97925-95-6. The substance/component is in the applicability domain of the model. All relevant related fragments show experimentally ready biodegradability. Thus the prediction is considered as valid.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Principles of method if other than guideline:
Calculation based on BIOWIN v4.10, Estimation Programs Interface Suite™ for Microsoft® Windows v 4.11. US EPA, United States Environmental Protection Agency, Washington, DC, USA.
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on results:
For detailed description on the model and its applicability, see "Any other information on materials and methods incl. tables".

Table: Ready biodegradability prediction using BIOWIN v4.1

Biowin1 (Linear Model Prediction)

0.8313

biodegrades fast

Biowin2 (Non-Linear Model Prediction):

0.6863

biodegrades fast

Biowin3 (Ultimate Biodegradation Timeframe):

2.9273

weeks

Biowin4 (Primary Biodegradation Timeframe):

3.6729

days-weeks

Biowin5 (MITI Linear Model Prediction) :

0.8854

biodegrades fast

Biowin6 (MITI Non-Linear Model Prediction):

0.9077

biodegrades fast

Biowin7 (Anaerobic Model Prediction):

0.0453

does not biodegrade fast

Ready Biodegradability Prediction:

 

yes

 

Interpretation of results:
readily biodegradable
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:
other: see 'Remark'
Remarks:
Validated QSAR model: Calculation for main component of Ethanol, 2,2'-iminobis-, N-(C13-15-branched and linear alkyl) derivs., CAS 97925-95-6. The substance/component is in the applicability domain of the models. Thus the prediction is considered as valid.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Principles of method if other than guideline:
Calculation based on VegaNIC version 1.0.8 using Ready biodegradability model (version 1.0.8)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)

Compound SMILES: CCCCCCCCCCCCCN(CCO)(CCO)

Experimental value: -Prediction: possible Ready Biodegradable

Structural Alerts: Bb9 (tridecane); Bb16 (propan-1-amine); Bb18 (heptanes); Bb20 (butane)

No. Specific Non-Biodegradable SAs: 0

No. Balanced Non-Biodegradable SAs: 0

No. Specific Biodegradable SAs: 0

No. Balanced Biodegradable SAs: 4

Reliability: Compound is in model Applicability Domain

Remarks for the prediction: none

 

Global AD Index

AD Index = 0.964

Explanation: predicted substance is into the Applicability Domain of the model.

Similar molecules with known experimental value

Similarity index = 0.928

Explanation: strongly similar compounds with known experimental value in the training set have been found.

Concordance for similar molecules

Concordance index = 1

Explanation: similar molecules found in the training set have experimental values that agree with the predicted value.

Accuracy of prediction for similar molecules

Accuracy index = 1

Explanation: accuracy of prediction for similar molecules found in the training set is good.

Atom Centered Fragments similarity check

ACF matching index = 1

Explanation: all atom centered fragment of the compound have been found in the compounds of the training set.

Interpretation of results:
readily biodegradable
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:
other: see 'Remark'
Remarks:
Validated QSAR model: Calculation for main component of Ethanol, 2,2'-iminobis-, N-(C13-15-branched and linear alkyl) derivs., CAS 97925-95-6. The substance/component is in the applicability domain of the models. Thus the prediction is considered as valid.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Principles of method if other than guideline:
Calculation based on BIOWIN v4.10, Estimation Programs Interface Suite™ for Microsoft® Windows v 4.11. US EPA, United States Environmental Protection Agency, Washington, DC, USA.
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on results:
For detailed description on the model and its applicability, see "Any other information on materials and methods incl. tables".

Table: Ready biodegradability prediction using BIOWIN v4.1

Biowin1 (Linear Model Prediction)

0.8180

biodegrades fast

Biowin2 (Non-Linear Model Prediction):

0.5949

biodegrades fast

Biowin3 (Ultimate Biodegradation Timeframe):

2.8653

weeks

Biowin4 (Primary Biodegradation Timeframe):

3.6325

days-weeks

Biowin5 (MITI Linear Model Prediction) :

0.9007

biodegrades fast

Biowin6 (MITI Non-Linear Model Prediction):

0.9118

biodegrades fast

Biowin7 (Anaerobic Model Prediction):

0.0973

does not biodegrade fast

Ready Biodegradability Prediction:

 

yes

 

Interpretation of results:
readily biodegradable
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:
other: see 'Remark'
Remarks:
Validated QSAR model. Calculation for main component of Ethanol, 2,2'-iminobis-, N-(C13-15-branched and linear alkyl) derivs., CAS 97925-95-6. The substance/component is in the applicability domain of the model. All relevant related fragments show experimentally ready biodegradability. Thus the prediction is considered as valid.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Principles of method if other than guideline:
Calculation based on VegaNIC version 1.0.8 using Ready biodegradability model (version 1.0.8)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)

Compound SMILES: OCCN(CCO)CCCCCCCCCCCCCCC

Experimental value: -

Prediction: possible Ready Biodegradable

Structural Alerts: Bb9 (tridecane); Bb16 (propan-1-amine); Bb18 (heptanes); Bb20 (butane)

No. Specific Non-Biodegradable SAs: 0

No. Balanced Non-Biodegradable SAs: 0

No. Specific Biodegradable SAs: 0

No. Balanced Biodegradable SAs: 4

Reliability: Compound is in model Applicability Domain

Remarks for the prediction: none

 

Global AD Index

AD Index = 0.965

Explanation: predicted substance is into the Applicability Domain of the model.

Similar molecules with known experimental value

Similarity index = 0.931

Explanation: strongly similar compounds with known experimental value in the training set have been found.

Concordance for similar molecules

Concordance index = 1

Explanation: similar molecules found in the training set have experimental values that agree with the predicted value.

Accuracy of prediction for similar molecules

Accuracy index = 1

Explanation: accuracy of prediction for similar molecules found in the training set is good.

Atom Centered Fragments similarity check

ACF matching index = 1

Explanation: all atom centered fragment of the compound have been found in the compounds of the training set.

Interpretation of results:
readily biodegradable

Description of key information

Atmer 163 is not readily biodegradable (37% after 28 days), but will be moderately biodegraded. This is supported by a (Q)SAR calculation using BIOWIN v4.10 and Vega Ready biodegradability model v1.0.8.

Key value for chemical safety assessment

Additional information

The ultimate biodegradability of Atmer 163 (CAS No. 97925-95-6) was assessed by Bealing (2002). The testing procedure was based on the ISO Standard 14593. The conditions employed are equivalent to those represented by the OECD 301 series ready biodegradability test methods.

Non adapted activated sludge from a STP treating predominantly domestic sewage was used as inoculum. At the end of the incubation (28 days), the test vessels contents were rendered alkaline to fix inorganic carbonates and to absorb CO2 from the headspace into the test medium. The inorganic carbon (IC) yield in each vessel was then determined by injecting measured volumes of the liquid phase into a carbon analyser. The mean final IC yield for Atmer 163 was 37% of the organic carbon dosed to the test system, indicating that significant, but incomplete mineralisation had occurred. As degradation did not reach 60% Atmer 163 does not qualify for classification as readily biodegradable, but will be moderately biodegraded and is not persistent in the environment.

This is supported by additional QSAR calculations using different models (BIOWIN 1 -6 v4.10; and VEGA Ready biodegradability model v1.0.8). Calculations were performed on main components of Atmer 163. Both components fit into the applicability domain of the models. The results show that the components of Atmer 163 are readily biodegradable, thus underlining the assessment that Atmer 163 is not persistent in the environment.