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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Guideline study performed under GLP. The source and target substances must have an aldehyde group at the 1-carbon position and either a terminal (10-position) or an internal alkene (9-position or 8-position; with the terminal alkyl group no larger than an ethyl group and/or should not multiply substituted). The substance alkyl chain length of the substance should be more than 6 carbons in length and less than 14 carbons in length and fulfil the mono-alkene definition. The substance should not have any branched alkyl groups or side chains. The target and source share common structural elements in the same relative positions. The source and target have very similar physico-chemical properties and therefore demonstrative chemical similarity.
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
Further information is included in attachment to IUCLID section 13.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The read-across is based on the hypothesis that the source and target substances have common structural features in the same relative positions. The source and target have similar physico-chemical, toxicological properties and because of common metabolism they share common or have similar breakdown products and therefore potential mechanisms of action. Further information is included in attachment to IUCLID section 13.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The source and target chemicals have comparable chemical similarity. Further information is included in attachment to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
The source substance is a chemically similar substance with common metabolism and common or similar degradants of the target substance. Further information is included in attachment to IUCLID section 13

4. DATA MATRIX
Further information is included in attachment to IUCLID section 13.
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
yes
Remarks:
toxicity control not performed
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
yes
Remarks:
toxicity control not performed
Qualifier:
according to
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
Deviations:
yes
Remarks:
toxicity control not performed
GLP compliance:
yes (incl. certificate)
Remarks:
inspected March 2008; signature: May 2008
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
Fresh activated sludge from a biological waste water treatment plant (Bois-de-Bay, Satigny, Switzerland) treating predominantly domestic sewage was used. The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day.
Duration of test (contact time):
33 d
Initial conc.:
20 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: See table 1.
- Solubilising agent (type and concentration if used): None.
- Test temperature: 22 °C
- pH: Measured prior to and completion of test. See table 2.
- pH adjusted: No
- Aeration of dilution water: Not reported
- Continuous darkness: Not reported

TEST SYSTEM
- Culturing apparatus: flasks with continuous stirring.
- Number of culture flasks/concentration: In duplicate.
- Method used to create aerobic conditions: Not reported
- Measuring equipment: The respirometer used during this study is an Oxitop Control System. The consumption of oxygen is determined by measuring the pressure drop in the respirometer flask. Evolved carbon dioxide is absorbed in sodium hydroxide pellets.

SAMPLING
- Sampling frequency: Daily.
- Sampling method: The respirometer used during this study is an Oxitop Control System.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes. See table 1.
- Abiotic sterile control: No
- Toxicity control: No
Reference substance:
benzoic acid, sodium salt
Remarks:
100 mg/l
Test performance:
The repeatability validity criterion (not more than 20% difference between replicates) is fulfilled for the flasks containing test substance. Therefore, the test is considered valid.
Parameter:
% degradation (O2 consumption)
Value:
82
Sampling time:
28 d
Details on results:
The test material undergoes 82% biodegradation after 28 days (84% after 33 days) in the test conditions. The 10-day window criterion is also fulfilled (23% biodegradation on day 2 and 62% on day 12).
Results with reference substance:
Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days: the activity of the inoculum was thus verified (validity criterion).
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
For the target substance: it is expected to undergo 82% biodegradation after 28 days (84% after 33 days). The 10-day window criterion does not apply (OECD 2006) as the target substance is a multi-constituent substance of structurally similar isomers. The target substance can be considered to be be readily biodegradable.
Executive summary:

The ready biodegradability test was carried out on a source substance according to OECD 301F, EU C.4 -D and EPA OPPTS 835.3110 guidelines under GLP. The source substance was added to an aqueous solution of mineral salts and exposed to relatively low numbers of micro-organisms under aerobic conditions for a period of 33 days. Activated sludge was obtained from the biological waste water treatment plant (Bois-de-Bay, Satigny, Switzerland - treating predominantly domestic sewage) and the inoculum added to give a final concentration of 20 mg dry material per test flask. The consumption of oxygen is determined by measuring the pressure drop in the respirometer flask (the respirometer used during this study is an Oxitop Control System). The dissolved oxygen concentrations were recorded at least once per day. The average biodegradation for duplicate test flasks at 28 days for the test substance was 82%. This test material satisfied the test criteria for ready degradability of 60% degradability within 28 days and the 10-day wind criterion was also fulfilled.

 

The target substance is expected to undergo 82% biodegradation after 28 days (84% after 33 days). The 10-day window criterion does not apply (OECD 2006) as the substance is a multi-constituent substance of structurally similar isomers. The target substance can be considered to be be readily biodegradable.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Guideline study performed under GLP. The source and target substances must have an aldehyde group at the 1-carbon position and either a terminal (10-position) or an internal alkene (9-position or 8-position; with the terminal alkyl group no larger than an ethyl group and/or should not multiply substituted). The substance alkyl chain length of the substance should be more than 6 carbons in length and less than 14 carbons in length and fulfil the mono-alkene definition. The substance should not have any branched alkyl groups or side chains. The target and source share common structural elements in the same relative positions. The source and target have very similar physico-chemical properties and therefore demonstrative chemical similarity.
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
yes
Remarks:
toxicity control not performed
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
yes
Remarks:
toxicity control not performed
Qualifier:
according to
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
Deviations:
yes
Remarks:
toxicity control not performed
GLP compliance:
yes (incl. certificate)
Remarks:
inspected March 2008; signature: May 2008
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
Fresh activated sludge from a biological waste water treatment plant (Bois-de-Bay, Satigny, Switzerland) treating predominantly domestic sewage was used. The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day.
Duration of test (contact time):
33 d
Initial conc.:
20 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: See table 1.
- Solubilising agent (type and concentration if used): None.
- Test temperature: 22 °C
- pH: Measured prior to and completion of test. See table 2.
- pH adjusted: No
- Aeration of dilution water: Not reported
- Continuous darkness: Not reported

TEST SYSTEM
- Culturing apparatus: flasks with continuous stirring.
- Number of culture flasks/concentration: In duplicate.
- Method used to create aerobic conditions: Not reported
- Measuring equipment: The respirometer used during this study is an Oxitop Control System. The consumption of oxygen is determined by measuring the pressure drop in the respirometer flask. Evolved carbon dioxide is absorbed in sodium hydroxide pellets.

SAMPLING
- Sampling frequency: Daily.
- Sampling method: The respirometer used during this study is an Oxitop Control System.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes. See table 1.
- Abiotic sterile control: No
- Toxicity control: No
Reference substance:
benzoic acid, sodium salt
Remarks:
100 mg/l
Test performance:
The repeatability validity criterion (not more than 20% difference between replicates) is fulfilled for the flasks containing test substance. Therefore, the test is considered valid.
Parameter:
% degradation (O2 consumption)
Value:
82
Sampling time:
28 d
Details on results:
The test material undergoes 82% biodegradation after 28 days (84% after 33 days) in the test conditions. The 10-day window criterion is also fulfilled (23% biodegradation on day 2 and 62% on day 12).
Results with reference substance:
Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days: the activity of the inoculum was thus verified (validity criterion).
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Under the conditions the test material undergoes 82% biodegradation after 28 days (84% after 33 days). The 10-day window criterion is also fulfilled (23% biodegradation on day 2 and 62% on day 12). The test material can be considered to be be readily biodegradable.
Executive summary:

The ready biodegradability test was carried out according to OECD 301F, EU C.4 -D and EPA OPPTS 835.3110 guidelines under GLP. The test substance was added to an aqueous solution of mineral salts and exposed to relatively low numbers of micro-organisms under aerobic conditions for a period of 33 days. Activated sludge was obtained from the biological waste water treatment plant (Bois-de-Bay, Satigny, Switzerland - treating predominantly domestic sewage) and the inoculum added to give a final concentration of 20 mg dry material per test flask. The consumption of oxygen is determined by measuring the pressure drop in the respirometer flask (the respirometer used during this study is an Oxitop Control System). The dissolved oxygen concentrations were recorded at least once per day. The average biodegradation for duplicate test flasks at 28 days for the test substance was 82%. This test material satisfied the test criteria for ready degradability of 60% degradability within 28 days and the 10-day wind criterion was also fulfilled.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
2018
Reliability:
2 (reliable with restrictions)
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
CATALOGIC Kinetic 301F v.13.16; within OASIS CATALOGIC v.5.12.1
Contact LMC University:
Prof. As. Zlatarov,
LMC University,
Laboratory of Mathematical Chemistry,
Bourgas,
Bulgaria
URL: www.oasis-lmc.org
More information available at:
http://oasis-lmc.org/products/models/environmental-fate-and-ecotoxicity/

2. MODEL (incl. version number)
CATALOGIC Kinetic 301F v.13.16
June 2014 (QMRF publication); updated: July 2017

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See QPRF attached: ‘QPRF Title: Substance: Reaction mass of (9E)-9-undecenal and (9Z)-9-undecenal and undec-10-enal using the model CATALOGIC Kinetic 301F v.13.16 within LMC OASIS CATALOGIC v5.12.1 for the endpoint: Ready Biodegradability’ version 1.0; 01 April 2018.

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Full details of the method are provided in the attached QMRF named ‘QMRF Title: CATALOGIC Kinetic 301F model for predicting biodegradability of chemicals’ - model: CATALOGIC Kinetic 301F v.13.16 - software package: OASIS CATALOGIC v.5.12.1, version 1.0; date: 01 June 2014; updated 01 July 2017.

5. APPLICABILITY DOMAIN
See ‘any other information on results incl. tables’.
See QPRF attached: ‘QPRF Title: Substance: Reaction mass of (9E)-9-undecenal and (9Z)-9-undecenal and undec-10-enal using the model CATALOGIC Kinetic 301F v.13.16 within LMC OASIS CATALOGIC v5.12.1 for the endpoint: Ready Biodegradability’ version 1.0; 01 April 2018.
- Descriptor domain: All constituents are in domain.
- Structural and mechanistic domains: All constituents are 100% correctly predicted ACF (in domain). All constituents are within the mechanistic domain.
Guideline:
other: REACH Guidance on QSARs R.6, May/July 2008
Principles of method if other than guideline:
Full details of the method are provided in the attached QMRF named ‘QMRF Title: CATALOGIC Kinetic 301F model for predicting biodegradability of chemicals’ - model: CATALOGIC Kinetic 301F v.13.16 - software package: OASIS CATALOGIC v.5.12.1, version 1.0; date: 01 June 2014; updated 01 July 2017.
- The model applies the following methodology to generate predictions:
The LMC stepwise approach was used to define the applicability domain. It contains three layers:
(i) General properties requirements (log KOW, MW, log WS)
(ii) Structural domain (Atom Cantered Fragments (ACFs))
(iii) Metabolic domain
Details could be found in:
Dimitrov S, Dimitrova G., Pavlov T., Dimitrova D., Patlevisz G., Niemela J., Mekenyan O., A stepwise approach for defining the applicability domain of SAR and QSAR models, J. Chem. Inf. Model., 45, 839-849 (2005)
- The model and the training sets are collated and published by Prof. As. Zlatarov, LMC University, (Bulgaria).
The training set of the model currently consists of 992 chemicals (proprietary)
The experimental Log Kow values in the training set and validation set were measured using one or more methods equivalent or similar to the following guidelines:
- OECD TG 301F or equivalent where appropriate.
A full list of experimental reference citations is provided in the CATALOGIC software with additional reference citations in the QMRF attached.
- Justification of QSAR prediction: The result should be considered in relation to corresponding information presented and in accordance with the tonnage driven information requirements of REACH Regulation (EC) 1907/2006 in a weight of evidence. For classification purposes, Regulation (EC) No 1272/2008 allows the use of non-standard approaches as mentioned in 4.1.1.2.2. Annex XI, 1.3 allows the use of a (Q)SAR instead of testing when certain conditions are met (use of valid (Q)SAR, adequate and reliable information is provided etc). For the PBT/vPvB assessment, the revised Annex XIII allows the use of any information provided its suitability and reliability can be reasonably demonstrated. The present predictions are intended to be used in a weight of evidence approach as mentioned in Annex IX, 1.2: using the present predictions to support experimental data (GLP ; completed to an applicable guideline OECD TG 301F) demonstrating that the ‘ready biodegradable’ criteria is achieved for the substance.
Specific details on test material used for the study:
Detailed information on the 'test material identity' is provided in the attached QSAR Prediction Reporting Format (QPRF) document including information on individual constituents.
Parameter:
% degradation (O2 consumption)
Value:
>= 80 - <= 82
Sampling time:
28 d
Remarks on result:
readily biodegradable based on QSAR/QSPR prediction
Remarks:
> 60 % pass level set by the OECD Guidelines for testing of Chemicals (301) for ready biodegradability of a substance. 10-day window criteria inapplicable on the substance type: multi-constituent of structurally similar constituents/isomers (OECD, 2006)

1. Defined Endpoint:

QMRF 2. Environmental Fate Parameters

QMRF 3. Persistence: Biodegradation: 2.3.a Ready Biodegradability

 

Reference to type of model used and description of results:

CATALOGIC Kinetic 301F v.13.16, July 2017

Platform version: OASIS Catalogic v5.12.1

 

2. Description of results and assessment of reliability of the prediction:

Summary: BOD [28]= from 0.80 to 0.82

Concomitant predictions

Primary Half Life = < 1 day

Ultimate Half Life from 11.34 days to 12.17 days

Start day of Calc. 10 days window : from day 4

BOD calc at 10 days window from 0.5797 to 0.6440

Classification of Calc. 10 days window :

Ready (when waiving 10-day window) for 2 chemicals ; Ready for 1 chemicals

Expert assessment was the used to review the outcome in the context of the substance-type: multi-constituent, as below (Ref: OECD 301 guidelines and OECD 2006 and GHS 2008 on the inapplicability of the 10-d window).

 

Full details of the constituents are provided in the attached ‘QPRF Title: Substance: Reaction mass of (9E)-9-undecenal and (9Z)-9-undecenal and undec-10-enal using the model CATALOGIC Kinetic 301F v.13.16 within LMC OASIS CATALOGIC v5.12.1 for the endpoint: Ready Biodegradability’ version 1.0; 01 April 2018

 

Assessment of the substance within the applicability domain as documented within the corresponding QMRF named ‘QMRF Title: Catalogic Kinetic 301F model for predicting biodegradability of chemicals’; updated QMRF: July 2017 – section 5; indicates:

That for all constituents:

a. Descriptors domain:

(i) Falls within the Log Kow domain of: Min -11.34 to Max 16.50 (general domain for the model)

(ii) Molecular weight: Min 31.06 to Max 1990.64 Daltons and

(iii) Water Solubility: Min 0.0 to Max 1000000 mg/L.

Input descriptors: SMILES

Constituent 1: Log Kow 4.04 (predicted KOWWIN v1.68); Mw: 168, WS (mg/L) 59.1 mg/L (predicted)

Constituent 2: Log Kow 4.04 (predicted KOWWIN v1.68); Mw: 168, WS (mg/L) 59.1 mg/L (predicted)

Constituent 3: Log Kow 4.12 (predicted KOWWIN v1.68); Mw: 168, WS (mg/L) 27.7 mg/L (predicted)

b. Structural domain (Atom Centred Fragments, ACFs):

The substance constituents are within the model structural domain. The high percentage of correctly predicted atom centred fragments (100%) allows that the conclusion that the predictions are relevant.

 

3. Uncertainty of the prediction and mechanistic domain:

The training set is embedded in the software of the model; refer to the QMRF which is available in OASIS Catalogic v5.12.1. The training set data is proprietary and not made publicly available by the model developers. It is noted that the software model itself determines if the test item falls within the general properties requirements [lipophilicity (log KOW), molecular weight (MW) and water solubility (WS)] domain; then the appropriate structural and mechanistic/metabolic domains. Full details are provided of the methodology in the corresponding QMRF (updated: 01 July 2017) for model CATALOGIC Kinetic 301F v13.16. No further comments on the uncertainty of the prediction are provided by the author of the present QPRF. A summary of this information is presented by the applicant in attachment with relevant citations.

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The results are adequate for the regulatory purpose.
Executive summary:

OASIS Catalogic v5.12.1 - CATALOGIC Kinetic 301F v.13.16, Ready Biodegradability, July 2017

Summary: BOD [28]= from 0.80 to 0.82

Substance will exhibit 80 – 82% biodegradation (BOD) at 28-d and exceeding the 60 % pass level set by the OECD Guidelines for testing of Chemicals (301).

Although the 10-day window criteria was not met for 2 of the constituents composing this multi-constituent substance, the nature of the substance (multi-constituent) precludes the application of a 10-day window when assessing the biodegradability of the substance as a whole (OECD, 2006). Additionally, this prediction is intended as supporting information in a weight-of-evidence approach that shows the substance to be readily biodegradable.

 

Adequacy of the QSAR:

1) QSAR model is scientifically valid. 2) The substance is within the domain of the (Q)SAR model. 3) The prediction is adequate as contributing data for the Classification and Labelling or risk assessment of the substance as indicated in REACH Regulation (EC) 1907/2006: Annex XI Section 1.3

Description of key information

Weight of evidence: readily biodegradable, 2018

1. Biodegradation (Read-Across: undec-10-enal): 82% (28-days; 10-d window met) readily biodegradable, OECD TG 301F, 2010

2. QSAR - OASIS CATALOGIC v5.12.1 - Kinetic 301F v13.16 (substance): 80 - 82% degradation within 28 -days (10-d window does not apply, OECD 2006), 2018

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

Key study: OECD 301F, 2010: Read-Across - SOURCE (undec-10-enal): The ready biodegradability test was carried out according to OECD 301F, EU C.4 -D and EPA OPPTS 835.3110 guidelines under GLP. The test substance was added to an aqueous solution of mineral salts and exposed to relatively low numbers of micro-organisms under aerobic conditions for a period of 33 days. Activated sludge was obtained from the biological waste water treatment plant (Bois-de-Bay, Satigny, Switzerland - treating predominantly domestic sewage) and the inoculum added to give a final concentration of 20 mg dry material per test flask. The consumption of oxygen is determined by measuring the pressure drop in the respirometer flask (the respirometer used during this study is an Oxitop Control System). The dissolved oxygen concentrations were recorded at least once per day. The average biodegradation for duplicate test flasks at 28 days for the test substance was 82%. This test material satisfied the test criteria for ready degradability of 60% degradability within 28 days and the 10-day window criterion was also fulfilled.

Key data: QSAR - OASIS Catalogic v5.12.1 - CATALOGIC Kinetic 301F v.13.16, Ready Biodegradability, 2018:

Summary: BOD [28]= from 0.80 to 0.82

Substance will exhibit 80 – 82% biodegradation (BOD) at 28-d and exceeding the 60 % pass level set by the OECD Guidelines for testing of Chemicals (301).

Although the 10-day window criteria was not met for 2 of the constituents composing this multi-constituent substance, the nature of the substance (multi-constituent) precludes the application of a 10-day window when assessing the biodegradability of the substance as a whole (OECD, 2006). Additionally, this prediction is intended as supporting information in a weight-of-evidence approach that shows the substance to be readily biodegradable.

Weight of Evidence: conclusion:

The substance consists of multiple-isomeric constituents that indicate clear evidence of rapid-degradability via biodegradation. They would be considered as fulfilling the criteria for rapid (ultimate) degradability and are expected to rapidly mineralise under environmental conditions in accordance with the CLP Regulation (EC) 1272/2008 and GHS revision 4 (2011) criteria. The 10-day window does not apply to multi-constituent substances of structurally similar components such as isomers (OECD 2006).