Reaction products of diazotized mixture of aniline, toluidines and xylidines coupled with mixture of aniline, toluidines and xylidines, subsequently diazotized then coupled with 2-naphthol

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

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:

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: Estimation Programs Interface Suite™ (EPI Suite) for Microsoft® Windows, v 4.11

2. MODEL (incl. version number): BIOWIN v 4.10

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
Structural formula: C17H14N2O
Structural codes:
a. SMILES: Cc3ccccc3/N=N/c1c2ccccc2ccc1O
b. InChI: InChI=1S/C17H14N2O/c1-12-6-2-5-9-15(12)18-19-17-14-8-4-3-7-13(14)10-11-16(17)20/h2-11,20H,1H3/b19-18+
c. Other structural representation: mol file

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: Persistence: biodegradation - ready/not ready biodegradability
- Unambiguous algorithm: BIOWIN1, 3, 5: linear regression; BIOWIN2, 6: non-linear regression. Further details are available on the attached QMRF.
- Defined domain of applicability: The applicability domain of BIOWIN models is based on the molecular weight of training set chemicals of different models and on the structural fragments represented in the models’ training set.
- Appropriate measures of goodness-of-fit and robustness and predictivity: Please see attached QMRF.
- Mechanistic interpretation: The fragments were selected based largely on known structural influences on aerobic biodegradability, such as the ester linkage which is hydrolyzed by microorganisms.

5. APPLICABILITY DOMAIN
The target compound Solvent Orange 2 (CAS No. 2646-17-5) is included in the model applicability domain since the MW of the target (MW: 262.31) falls within the MW range of training set chemicals, and the target compound structure possesses structural fragments represented in the training set chemicals of different models.
- Descriptor domain: not applicable
- Structural fragment domain: the target possesses structural fragments represented in both Biowin 1-3 training set compounds (NB1-2=295; NB3=200), and Biowin 5-6 training set compounds (NB5-6=589). The number of instances of the identified fragments do not exceed the maximum for all training set compounds. Further details about the identified fragments are available on the attached QPRF.
- Mechanistic domain: Not applicable.
- Similarity with analogues in the training set: No structural analogues from the training set are provided by BIOWIN.

6. ADEQUACY OF THE RESULT
A Not Ready Biodegradable (NRB) prediction was estimated for the target Solvent Orange 2 (CAS No. 2646-17-5). The prediction was assessed as moderately reliable. The ready biodegradability QSAR prediction was assessed as adequate for regulatory purposes.

Qualifier:

according to guideline

Guideline:

other:

Version / remarks:

REACH Guidance on QSARs R.6 (2008)

Principles of method if other than guideline:

- Software tool(s) used including version: Estimation Programs Interface Suite™ (EPI Suite) for Microsoft® Windows, v 4.11
- Model(s) used: BIOWIN v 4.10
- Model description: see field 'Justification for type of information' and 'Attached justification'
- Justification of QSAR prediction: see field 'Justification for type of information' and 'Attached justification'

Specific details on test material used for the study:

SMILES: Cc3ccccc3/N=N/c1c2ccccc2ccc1O

Key result

Parameter:

other: Not Ready Biodegradable

Remarks on result:

not readily biodegradable based on QSAR/QSPR prediction

Prediction based on Biowin 2, 3, 5, and 6 models. In more detail, Biowin 3 predicted an ultimate biodegradation timeframe of weeks-months, based on a predicted value of 2.30, and Biowin 5-6 MITI models predicted the target compound as not ready biodegradable, based on RB probabilities far below 0.5. These predictions were also consistent with Biowin 2 model, which predicted the target as not ready biodegradable based on a RB probability below 0.5. On the contrary, the fast biodegradation probability provided by Biowin 1 was not taken into account in the assessment, since its biodegradability probability score falls between 0.4 and 0.6, and thus close to the cut-off point of 0.5 between ready and not ready biodegradability [ECHA Chapter R.7b, 2017]. The analysis of the chemical structure highlighted the presence of structural features/functional groups in the target compound which are recalcitrant to biodegradation (e.g., azo group, fused aromatic ring system).

Limited uncertainty was associated with the NRB prediction provided by BIOWIN models due to the following considerations: a) the four Biowin models considered provided consistent not ready biodegradable predictions; b) the target is included in the AD of the four Biowin models considered (MW within the range of training set compounds, all fragments well represented in the training set).

Overall, the target compound Solvent Orange 2 (CAS No. 2646 -17 -5) was predicted as not ready biodegradable.

Interpretation of results:

not readily biodegradable

Remarks:

Based on QSAR prediction

Conclusions:

A Not Ready Biodegradable (NRB) prediction was estimated for the target Solvent Orange 2 (CAS No. 2646-17-5). The prediction was assessed as moderately reliable.

Executive summary:

This study was designed to generate estimated in silico (non-testing) data for Solvent Orange 2 (CAS No. 2646-17-5) to be used for its hazard assessment. QSAR prediction was provided for the ready biodegradability endpoint. A reliability score of 2 was assigned, since results derived from a valid QSAR model and falling into its applicability domain, with adequate and reliable documentation/justification. The BIOWIN model implemented in EPI Suite (v 4.11) was employed. BIOWIN contains separate models that calculate the probability of ready biodegradability, based upon fragment constants that were developed using multiple linear or non-linear regression analyses: i) Biowin1 (linear probability model), ii) Biowin2 (non-linear probability model), iii) Biowin3 (expert survey ultimate biodegradation model), iv) Biowin5 (MITI linear model), v) Biowin6 (MITI non-linear model). In addition, a categorical prediction (YES or NO) is provided by BIOWIN based on a combination of Biowin3 and Biowin5 results. A Not Ready Biodegradable (NRB) prediction was estimated for the target Solvent Orange 2 (CAS No. 2646-17-5). The prediction was assessed as moderately reliable, based on the following considerations:

- the four Biowin models considered provided consistent not ready biodegradable predictions;

- the target is included in the AD of the four Biowin models considered (MW within the range of training set compounds, all fragments well represented in the training set).

The ready biodegradability QSAR prediction was assessed as adequate for regulatory purposes.

Reference 2

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:

results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE: Estimation Programs Interface Suite™ (EPI Suite) for Microsoft® Windows, v 4.11

2. MODEL (incl. version number): BIOWIN v 4.10

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
Structural formula: C24H20N4O
Structural codes:
a. SMILES: Cc4ccccc4/N=N/c3ccc(/N=N/c1c2ccccc2ccc1O)c(C)c3
b. InChI: InChI=1S/C24H20N4O/c1-16-7-3-6-10-21(16)26-25-19-12-13-22(17(2)15-19)27-28-24-20-9-5-4-8-18(20)11-14-23(24)29/h3-15,29H,1-2H3/b26-25+,28-27+
c. Other structural representation: mol file

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: Persistence: biodegradation - ready/not ready biodegradability
- Unambiguous algorithm: BIOWIN1, 3, 5: linear regression; BIOWIN2, 6: non-linear regression. Further details are available on the attached QMRF.
- Defined domain of applicability: The applicability domain of BIOWIN models is based on the molecular weight of training set chemicals of different models and on the structural fragments represented in the models’ training set.
- Appropriate measures of goodness-of-fit and robustness and predictivity: Please see attached QMRF.
- Mechanistic interpretation: The fragments were selected based largely on known structural influences on aerobic biodegradability, such as the ester linkage which is hydrolyzed by microorganisms.

5. APPLICABILITY DOMAIN
The target compound Solvent Red 24 (CAS No. 85-83-6) is partially included in the model applicability domain since the MW of the target (MW: 380.45) falls within the MW range of training set chemicals, but it possesses one more instance for the structural fragment azo group [-N=N-] than the maximum for all training set compounds of different models.
- Descriptor domain: not applicable
- Structural fragment domain: the target possesses structural fragments represented in both Biowin 1-3 training set compounds (NB1-2=295; NB3=200), and in Biowin 5-6 training set compounds (NB5-6=589). The number of instances of the identified fragments do not exceed the maximum for all training set compounds, with the only exception of the azo group [-N=N-], where one more instance than the maximum for all training set compounds was found. Further details about the identified fragments are available on the attached QPRF.
- Mechanistic domain: Not applicable.
- Similarity with analogues in the training set: No structural analogues from the training set are provided by BIOWIN.

6. ADEQUACY OF THE RESULT
A Not Ready Biodegradable (NRB) prediction was estimated for the target Solvent Red 24 (CAS No. 85-83-6). The prediction was assessed as moderately reliable. The ready biodegradability QSAR prediction was assessed as adequate for regulatory purposes.

Qualifier:

according to guideline

Guideline:

other:

Version / remarks:

REACH Guidance on QSARs R.6 (2008)

Principles of method if other than guideline:

- Software tool(s) used including version: Estimation Programs Interface Suite™ (EPI Suite) for Microsoft® Windows, v 4.11
- Model(s) used: BIOWIN v 4.10
- Model description: see field 'Justification for type of information' and 'Attached justification'
- Justification of QSAR prediction: see field 'Justification for type of information' and 'Attached justification'

Specific details on test material used for the study:

SMILES: Cc4ccccc4/N=N/c3ccc(/N=N/c1c2ccccc2ccc1O)c(C)c3

Key result

Parameter:

other: Not Ready Biodegradable

Remarks on result:

not readily biodegradable based on QSAR/QSPR prediction

Prediction based on Biowin 1, 2, 3, 5 and 6 models. In more detail, Biowin3 predicted the target compound as being recalcitrant based on an ultimate biodegradation timeframe longer than months (predicted value equal to 1.66), and Biowin 5-6 MITI models predicted the target compound as not ready biodegradable, based on RB probabilities far below 0.5. These predictions were also consistent with Biowin 1-2 models, which predicted the target as not ready biodegradable based on RB probabilities below 0.5. The analysis of the chemical structure highlighted the presence of structural features/functional groups in the target compound which are recalcitrant to biodegradation (e.g., azo group, alkyl substituent on aromatic ring, fused aromatic ring system). Limited uncertainty was associated with the NRB prediction provided by BIOWIN models due to the following considerations: a) the five Biowin models considered provided consistent not ready biodegradable predictions; b) the target is partially included in the AD of the five Biowin models (MW within the range of training set compounds, all fragments but one well represented in the training set).

Overall, the target compound Solvent Red 24 (CAS No. 85-83-6) was predicted as not ready biodegradable.    

Interpretation of results:

not readily biodegradable

Remarks:

Based on QSAR prediction

Conclusions:

A Not Ready Biodegradable (NRB) prediction was estimated for the target Solvent Red 24 (CAS No. 85-83-6). The prediction was assessed as moderately reliable.

Executive summary:

This study was designed to generate estimated in silico (non-testing) data for Solvent Red 24 (CAS No. 85-83-6) to be used for its hazard assessment. QSAR prediction was provided for the ready biodegradability endpoint. A reliability score of 2 was assigned, since results derived from a valid QSAR model and (partially) falling into its applicability domain, with adequate and reliable documentation/justification. The BIOWIN model implemented in EPI Suite (v 4.11) was employed. BIOWIN contains separate models that calculate the probability of ready biodegradability, based upon fragment constants that were developed using multiple linear or non-linear regression analyses: i) Biowin1 (linear probability model), ii) Biowin2 (non-linear probability model), iii) Biowin3 (expert survey ultimate biodegradation model), iv) Biowin5 (MITI linear model), v) Biowin6 (MITI non-linear model). In addition, a categorical prediction (YES or NO) is provided by BIOWIN based on a combination of Biowin3 and Biowin5 results.

A Not Ready Biodegradable (NRB) prediction was estimated for the target Solvent Red 24 (CAS No. 85-83-6). The prediction was assessed as moderately reliable, based on the following considerations:

- the five Biowin models considered provided consistent not ready biodegradable predictions;

- the target is partially included in the AD of the five Biowin models (MW within the range of training set compounds, all fragments but one well represented in the training set).

The ready biodegradability QSAR prediction was assessed as adequate for regulatory purposes.

Reference 3

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:

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: Estimation Programs Interface Suite™ (EPI Suite) for Microsoft® Windows, v 4.11

2. MODEL (incl. version number): BIOWIN v 4.10

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
Structural formula: C16H12N2O
Structural codes:
a. SMILES: Oc3ccc1ccccc1c3/N=N/c2ccccc2
b. InChI: InChI=1S/C16H12N2O/c19-15-11-10-12-6-4-5-9-14(12)16(15)18-17-13-7-2-1-3-8-13/h1-11,19H/b18-17+
c. Other structural representation: mol file

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: Persistence: biodegradation - ready/not ready biodegradability
- Unambiguous algorithm: BIOWIN1, 3, 5: linear regression; BIOWIN2, 6: non-linear regression. Further details are available on the attached QMRF.
- Defined domain of applicability: The applicability domain of BIOWIN models is based on the molecular weight of training set chemicals of different models and on the structural fragments represented in the models’ training set.
- Appropriate measures of goodness-of-fit and robustness and predictivity: Please see attached QMRF.
- Mechanistic interpretation: The fragments were selected based largely on known structural influences on aerobic biodegradability, such as the ester linkage which is hydrolyzed by microorganisms.

5. APPLICABILITY DOMAIN
The target compound Solvent Yellow 14 (CAS No. 842-07-9) is included in the model applicability domain since the MW of the target (MW: 248.28) falls within the MW range of training set chemicals, and the target compound structure possesses structural fragments represented in the training set chemicals of different models.
- Descriptor domain: not applicable
- Structural fragment domain: the target possesses structural fragments represented in both Biowin 1-3 training set compounds (NB1-2=295; NB3=200), and Biowin 5-6 training set compounds (NB5-6=589). The number of instances of the identified fragments do not exceed the maximum for all training set compounds. Further details about the identified fragments are available on the attached QPRF.
- Mechanistic domain: Not applicable.
- Similarity with analogues in the training set: No structural analogues from the training set are provided by BIOWIN.

6. ADEQUACY OF THE RESULT
A Not Ready Biodegradable (NRB) prediction was estimated for the target Solvent Yellow 14 (CAS No. 842-07-9). The prediction was assessed as moderately reliable. The ready biodegradability QSAR prediction was assessed as adequate for regulatory purposes.

Qualifier:

according to guideline

Guideline:

other:

Version / remarks:

REACH Guidance on QSARs R.6 (2008)

Principles of method if other than guideline:

- Software tool(s) used including version: Estimation Programs Interface Suite™ (EPI Suite) for Microsoft® Windows, v 4.11
- Model(s) used: BIOWIN v 4.10
- Model description: see field 'Justification for type of information' and 'Attached justification'
- Justification of QSAR prediction: see field 'Justification for type of information' and 'Attached justification'

Specific details on test material used for the study:

SMILES: Oc3ccc1ccccc1c3/N=N/c2ccccc2

Key result

Parameter:

other: Not Ready Biodegradable

Remarks on result:

not readily biodegradable based on QSAR/QSPR prediction

Prediction based on Biowin 2, 3, 5 and 6 models. In more detail, Biowin 3 predicted an ultimate biodegradation timeframe of weeks-months, based on a predicted value of 2.43, and Biowin 5-6 MITI models predicted the target compound as not ready biodegradable, based on RB probabilities far below 0.5. These predictions were also consistent with Biowin 2 model, which predicted the target as not ready biodegradable based on a RB probability below 0.5. On the contrary, Biowin 1 provided a fast biodegradation prediction (predicted value of 0.63), which was not consistent with the estimated results of the other Biowin models.

The analysis of the chemical structure highlighted the presence of structural features/functional groups in the target compound which are recalcitrant to biodegradation (e.g., azo group, fused aromatic ring system).

Limited uncertainty was associated with the NRB prediction provided by BIOWIN models due to the following considerations:

- all but one of the Biowin models provided consistent not ready biodegradable predictions;

- the target is included in the AD of the Biowin models considered (MW within the range of training set compounds, all fragments well represented in the training set).

Overall, the target compound Solvent Yellow 14 (CAS No. 842-07-9) was predicted as not ready biodegradable, and the prediction was assessed as moderately reliable.

Interpretation of results:

not readily biodegradable

Remarks:

Based on QSAR prediction

Conclusions:

A Not Ready Biodegradable (NRB) prediction was estimated for the target Solvent Yellow 14 (CAS No. 842-07-9). The prediction was assessed as moderately reliable.

Executive summary:

This study was designed to generate estimated in silico (non-testing) data for Solvent Yellow 14 (CAS No. 842-07-9) to be used for its hazard assessment. QSAR prediction was provided for the ready biodegradability endpoint. A reliability score of 2 was assigned, since results derived from a valid QSAR model and falling into its applicability domain, with adequate and reliable documentation/justification. The BIOWIN model implemented in EPI Suite (v 4.11) was employed. BIOWIN contains separate models that calculate the probability of ready biodegradability, based upon fragment constants that were developed using multiple linear or non-linear regression analyses: i) Biowin1 (linear probability model), ii) Biowin2 (non-linear probability model), iii) Biowin3 (expert survey ultimate biodegradation model), iv) Biowin5 (MITI linear model), v) Biowin6 (MITI non-linear model). In addition, a categorical prediction (YES or NO) is provided by BIOWIN based on a combination of Biowin3 and Biowin5 results. A Not Ready Biodegradable (NRB) prediction was estimated for the target Solvent Yellow 14 (CAS No. 842-07-9). The prediction was assessed as moderately reliable, based on the following considerations:

- all but one of the Biowin models provided consistent not ready biodegradable predictions;

- the target is included in the AD of the Biowin models considered (MW within the range of training set compounds, all fragments well represented in the training set).

The ready biodegradability QSAR prediction was assessed as adequate for regulatory purposes.

Reference 4

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

yes

Remarks:

without impact on the study conclusion

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Activated sludge was collected from the exit of the aeration tank, or near the exit from the tank, of a well-operated wastewater treatment plant receiving predominantly domestic sewage.
The sludge was settled and the liquid supernatant discarded. The concentrated sludge was then suspended in the mineral solution. These two steps were repeated twice.

Duration of test (contact time):

<= 28 d

Initial conc.:

100 mg/L

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Test solution preparation:
As the test item is poorly soluble in test condition, the test item was first dissolved in dichloromethane at approximately 5 g/L and then 5 mL of this solution were applied on silica gel in test vessels to obtain 25 mg of test item by test vessels. Subsequently, the solvent was evaporated with an oven. The same quantity of silica gel and dichloromethane were introduced in each test vessel.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

2.7

Sampling time:

28 d

Details on results:

The study is valid since:
-Based on a biodegradation rate higher than 60% in 14 days (experimental value: 66.6 and 72.0 % in 6 days) in the reference control, the test was carried out under good conditions.
-At the end of the test, measurements of Biological Oxygen Demand (BOD) in two replicates of the test item solution did not show a difference of more than 20% (experimental value: 0% and 5%).
-The oxygen uptake of the control was not greater than 60 mg.L-1 in 28 days (experimental value: 20.9 mg O2.L-1).
-Based on a biodegradation rate higher than 25% in 14 days (experimental value: 34.3 % in 13 days) in the toxicity control, the test item was not toxic to micro-organisms.

Results with reference substance:

The biodegradation rate of the reference substance was higher than 60% in 14 days (experimental value: 66.6 and 72.0 % in 6 days).

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

Solvent Red 24 mix was not readily biodegradable based on a biodegradation rate of 2.7% after 28 days.

Description of key information

Solvent Red 24 mix was tested for biodegradation in water through two kind of tests: one experimental test and one in silico (QSAR) test.

The experimental test is the key study and was performed on Solvent Red 24 mix (=UVCB).

The QSAR analysis is a supporting study and focused on the three constituents chemically well defined of the UVCB substance, i.e. SR24, SY14 and SO2.

Both approaches gave the same conclusion, i.e. the substance Solvent Red 24 mix is not readily biodegradable.

Details regarding the QSAR conclusion for ready biodegradability:

Solvent Red 24 Mix is a UVCB substance, mainly composed of three chemically defined constituents: Solvent Red 24 (CAS No. 85-83-6, composition percentage >85%), Solvent Orange 2 (CAS No. 2646-17-5, composition percentage <10%), and Solvent Yellow 14 (CAS No. 842-07-9, composition percentage <5%). More specifically, the constituent Solvent Red 24 was considered as the representative substance of the substance family 2-Naphthalenol, 1-[[4-(phenylazo)phenyl]azo]-, ar',ar''-Me derivatives (CAS No. 70879-65-1), the latter of which represents the overall major constituent (>85%) of the UVCB Solvent Red 24 Mix. The substance Solvent Red 24 is a mono-constituent substance with an expected concentration greater than 40% in 2-naphthalenol, 1-[[4-(phenylazo)phenyl]azo]-, ar',ar''-Me derivs., and with a concentration between 35 and 55% in the UVCB Solvent Red 24 Mix.

QSAR predictions for the ready biodegradability property were provided for the three main constituents of the UVCB, which were predicted to be not ready biodegradable with a moderate level of confidence.

Based on the obtained QSAR predictions, an overall not ready biodegradable conclusion was derived for the UVCB target substance Solvent Red 24 Mix. A summary table is reported below:

Summary of the in silico predictions for environmental properties.

Name (CAS No.)	Concentration %	Endpoint	Prediction	Reliability assessment	Adequacy
		ENVIRONMENTAL PROPERTIES
Solvent Red 24 (85-83-6)	85%*	Ready biodegradability	NRB^a	Moderate Reliable	Adequate (Klimisch 2)
Solvent Orange 2 (2646-17-5)	10%		NRB^a	Moderate Reliable	Adequate (Klimisch 2)
Solvent Yellow 14 (842-07-9)	5%		NRB^a	Moderate Reliable	Adequate (Klimisch 2)
Solvent Red 24 Mix (UVCB)	--	Weighted mean approach	NRB	--	--

NRB: Not Ready Biodegradable

**Concentration percentage of the main constituent Solvent Red 24 was adjusted from > 80% to 85% in order to reach a total composition percentage of 100% in the UVCB substance for the weighted mean calculation.

^aPrediction generated with EPI Suite/BIOWIN.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed