Reaction products of tetrabromophthalic anhydride with 2,2'-oxydiethanol and methyloxirane

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

1. SOFTWARE: EPIWIN 4.1

2. MODEL (incl. version number)
ECOSAR 1.11
3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
CAS: 77098-07-8 based on the lowest molecular weight component as worst case assessment for highest bioavailability
4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
[Explain how the model fulfils the OECD principles for (Q)SAR model validation. Consider attaching the QMRF or providing a link]
- Defined endpoint: see attached QMRF
- Unambiguous algorithm: yes
- Defined domain of applicability: yes within the applicability domain
- Appropriate measures of goodness-of-fit and robustness and predictivity: yes
- Mechanistic interpretation:

5. APPLICABILITY DOMAIN
[Explain how the substance falls within the applicability domain of the model]
- Descriptor domain: MW < 1000 actual value: 628, log Kow < 6: actual value: 3.8 (predicted)
- Structural and mechanistic domains: Esters, correct for the substance group
- Similarity with analogues in the training set: yes phthalate is part of the structure.

6. ADEQUACY OF THE RESULT

Qualifier:

no guideline required

Version / remarks:

QSAR

Principles of method if other than guideline:

- Software tool(s) used including version: EPIWIN 4.1
- Model(s) used: ECOSAR 1.11
- Model description: see field 'Justification for non-standard information', 'Attached justification' and/or 'Cross-reference'
- Justification of QSAR prediction: see field 'Justification for type of information', 'Attached justification' and/or 'Cross-reference'

GLP compliance:

no

Specific details on test material used for the study:

The results were obtained with a second possible structure of the component group with one aromatic ring, with smiles C(=O)(c1c(C(=O)OCC(C)OCC(C)OCC(C)O)c(Br)c(Br)c(Br)c1Br)OCCOCCO.

Test organisms (species):

Eisenia sp.

Animal group:

annelids

Study type:

other: QSAR

Total exposure duration:

14 d

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

ca. 2 023 mg/kg soil dw

Conc. based on:

other: second component one ring

Basis for effect:

mortality

Details on results:

The results were obtained with a second possible structure of the component group with one aromatic ring, with smiles C(=O)(c1c(C(=O)OCC(C)OCC(C)OCC(C)O)c(Br)c(Br)c(Br)c1Br)OCCOCCO.

Validity criteria fulfilled:

not applicable

Conclusions:

The results were obtained with a second possible structure of the component group with one aromatic ring, with smiles C(=O)(c1c(C(=O)OCC(C)OCC(C)OCC(C)O)c(Br)c(Br)c(Br)c1Br)OCCOCCO. It is very similar to the one of the lowest molecular weight component and also is still in the applicability domain of the model. Based on the QSAR estimate this component obtained with a valid structural group the LC50 for earthworms was predicted to be 2023 mg/kg dry weight. Indicating a very low toxicity to earthworms. The two components calcualted represent a worst case estimate of the toxicity of the UVCB components. Components with three or more rings fall outside the applicability domain of the model as they have molecular weights > 1000 and log Kow > 6. They are not expected to be bioavailable.

Executive summary:

Testing an oligomeric mixture is technically difficult to impossible. Therefore the toxicity to earthworms was estimatet using an accepted QSAR calculation method. The model was the US EPA EPIWIN model version 4.1, ECOSAR verision 1.11. The lowest molecular weight components werr used as the worst case estimate as this is supposed to have the highest bioavailability. This structure was within the applicability domain of the model (Mw <1000 and log Kow < 6) as it has a molecular weight of 744 and a predicted log Kow of 4.1. The structural group was esters, which is applicable to the structure of the test substance.

Based on the QSAR estimate of the lowest molecular weight component obtained with a valid structural group the LC50 for earthworms was predicted to be 2023 mg/kg dry weight. Indicating a very low toxicity to earthworms. The two  components calcualted  represent a worst case estimate of the toxicity of the UVCB components. Components with three or more rings fall outside the applicability domain of the model as they have molecular weights > 1000 and log Kow > 6. They are not expected to be bioavailable.

Reference 2

Endpoint:

toxicity to soil macroorganisms except arthropods, other

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

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: EPIWIN 4.1

2. MODEL (incl. version number)
ECOSAR 1.11
3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
CAS: 77098-07-8 based on the lowest molecular weight component as worst case assessment for highest bioavailability
4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
[Explain how the model fulfils the OECD principles for (Q)SAR model validation. Consider attaching the QMRF or providing a link]
- Defined endpoint: see attached QMRF
- Unambiguous algorithm: yes
- Defined domain of applicability: yes within the applicability domain
- Appropriate measures of goodness-of-fit and robustness and predictivity: yes
- Mechanistic interpretation:

5. APPLICABILITY DOMAIN
[Explain how the substance falls within the applicability domain of the model]
- Descriptor domain: MW < 1000 actual value: 628, log Kow < 6: actual value: 3.8 (predicted)
- Structural and mechanistic domains: Esters, correct for the substance group
- Similarity with analogues in the training set: yes phthalate is part of the structure.

6. ADEQUACY OF THE RESULT
[Explain how the prediction fits the purpose of classification and labelling and/or risk assessment]

Qualifier:

no guideline required

Principles of method if other than guideline:

- Software tool(s) used including version: Epiweb version 4.1
- Model(s) used: ECOSAR version 1.11
- Model description: see field 'Justification for non-standard information', 'Attached justification' and/or 'Cross-reference'
- Justification of QSAR prediction: see field 'Justification for type of information', 'Attached justification' and/or 'Cross-reference'

GLP compliance:

no

Test organisms (species):

Eisenia sp.

Animal group:

annelids

Study type:

other: QSAR

Total exposure duration:

14 d

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

ca. 2 111 mg/kg soil dw

Conc. based on:

other: lowest molecular weight component

Basis for effect:

mortality

Validity criteria fulfilled:

not applicable

Conclusions:

Based on the QSAR estimate of the lowest molecular weight component obtained with a valid structural group the LC50 for earthworms was predicted to be 2111 mg/kg dry weight. Indicating a very low toxicity to earthworms. The component represents a worst case estimate of the toxicity of the UVCB components.

Executive summary:

Testing an oligomeric mixture is technically difficult to impossible. Therefore the toxicity to earthworms was estimatet using an accepted QSAR calculation method. The model was the US EPA EPIWIN model version 4.1, ECOSAR version 1.11. The lowest molecular weight component was used as the worst case estimate as this is supposed to have the highest bioavailability. This structure was within the applicability domain of the model (Mw <1000 and log Kow < 6) as it has a molecular weight of 627.91 and a predicted log Kow of 3.8. The structural group was esters, which is applicable to the structure of the test substance.

Based on the QSAR estimate of the lowest molecular weight component obtained with a valid structural group the LC50 for earthworms was predicted to be 2111 mg/kg dry weight. Indicating a very low toxicity to earthworms. The component represents a worst case estimate of the toxicity of the UVCB components.

Reference 3

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

1. SOFTWARE OECD QSAR Toolbox

2. MODEL (incl. version number)OECD QSAR Toolbox
Version 4.2

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
CAS: 20566-35-2
4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL

See attached QRF
6. ADEQUACY OF THE RESULT .
The substance is in the applicability domain of the model. 7 analogs are considered, R2 is 8.22 abnalogs are mostly esters.

Principles of method if other than guideline:

- Software tool(s) used including version: OECD QSAR Toolbox
- Model(s) used: version 4.2
- Model description: see Attached justification
- Justification of QSAR prediction: Attached justification

GLP compliance:

no

Specific details on test material used for the study:

Here the lowest molecular weight component CAS: 20566-35-2 was modeled.

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Study type:

other: QSAR

Total exposure duration:

14 d

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

ca. 19.4 mg/kg soil ww

Nominal / measured:

estimated

Conc. based on:

other: low molecular weight component

Basis for effect:

mortality

Validity criteria fulfilled:

not applicable

Conclusions:

Based on the QSAR estimate of the lowest molecular weight component obtained with a valid structural group the LC50 for earthworms was predicted to be 19 mg/kg dry weight. Indicating a ow toxicity to earthworms. The component represents a worst case estimate of the toxicity of the UVCB components.
The Toolbox model predicts a lower toxicity than Epiwin and this value may be used as a worst case assumption. It is based on more molecules in the set of analogs, but the structural simialrity is less pronounced.

Executive summary:

Testing an oligomeric mixture is technically difficult to impossible. Therefore the toxicity to earthworms was estimatet using an accepted QSAR calculation method. The model was OECD Toolbox version 4.2. The lowest molecular weight component was used as the worst case estimate as this is supposed to have the highest bioavailability. This structure was within the applicability domain of the model.

Based on the QSAR estimate of the lowest molecular weight component obtained with a valid structural group the LC50 for earthworms was predicted to be 19 mg/kg dry weight. Indicating a ow toxicity to earthworms. The component represents a worst case estimate of the toxicity of the UVCB components.

The Toolbox model predicts a lower toxicity than Epiwin and this value may be used as a worst case assumption. It is based on more molecules in the set of analogs, but the structural simialrity is less pronounced.  

Reference 4

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

1. SOFTWARE OECD QSAR Toolbox

2. MODEL (incl. version number)OECD QSAR Toolbox
Version 4.2

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
SMILES: CC(O)COC(C)COC(=O)c1c(Br)c(Br)c(Br)c(Br)c1C(=O)OCCOCCO
4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL

See attached QRF
6. ADEQUACY OF THE RESULT .
The substance is in the applicability domain of the model. 7 analogs are considered, R2 is 8.22 analogs are mostly esters.
The component modelled is par tof the one-ring fraction with one diethyleneglycol and two propyleneglycol units. The calculated log Kow is in the applicaility domain of the model.

Principles of method if other than guideline:

- Software tool(s) used including version: OECD Toolbox version 4.2
- Model description: see Attached justification
- Justification of QSAR prediction: see Attached justification

GLP compliance:

no

Specific details on test material used for the study:

Here a low molecular one ring component with smiles CC(O)COC(C)COC(=O)c1c(Br)c(Br)c(Br)c(Br)c1C(=O)OCCOCCO was modeled

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Study type:

other: QSAR

Total exposure duration:

14 d

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

ca. 26.7 mg/kg soil ww

Nominal / measured:

estimated

Conc. based on:

other: component with smiles above

Basis for effect:

mortality

Validity criteria fulfilled:

not applicable

Conclusions:

Based on the QSAR estimate of one of the lower molecular weight components obtained with a valid structural group the LC50 for earthworms was predicted to be 26.7 mg/kg dry weight, indicating a low toxicity to earthworms. The component has a slightly higher LC50 value than the lowest molecular weight component modeled as well and confirms that the former represents a worst case estimate of the toxicity of the UVCB components.
The Toolbox model predicts a lower toxicity than Epiwin and this value may be used as a worst case assumption. It is based on more molecules in the set of analogs, but the structural similarity is less pronounced.

Executive summary:

Testing an oligomeric mixture is technically difficult to impossible. Therefore the toxicity to earthworms was estimatet using an accepted QSAR calculation method. The model was OECD Toolbox version 4.2. Based on the QSAR estimate of one of the lower molecular weight components obtained with a valid structural group the LC50 for earthworms was predicted to be 26.7 mg/kg dry weight, indicating a low toxicity to earthworms. The component has a slightly higher LC50 value than the lowest molecular weight component modeled as well and confirms that the former represents a worst case estimate of the toxicity of the UVCB components.

The Toolbox model predicts a lower toxicity than Epiwin and this value may be used as a worst case assumption. It is based on more molecules in the set of analogs, but the structural simialrity is less pronounced.  

Reference 5

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

1. SOFTWARE OECD QSAR Toolbox

2. MODEL (incl. version number)OECD QSAR Toolbox
Version 4.2

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
SMILES: CC(O)COC(C)COC(C)COC(=O)c1c(Br)c(Br)c(Br)c(Br)c1C(=O)OCCOCCO
4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL

See attached QRF
6. ADEQUACY OF THE RESULT .
The substance is in the applicability domain of the model. 7 analogs are considered, R2 is 8.22 analogs are mostly esters.
The component modelled is par tof the one-ring fraction with one diethyleneglycol and two propyleneglycol units. The calculated log Kow is in the applicaility domain of the model.

Principles of method if other than guideline:

- Software tool(s) used including version: OECD Toolbox version 4.2
- Model description: see Attached justification
- Justification of QSAR prediction: see Attached justification

GLP compliance:

no

Specific details on test material used for the study:

Here one of the lower molecular weight one ring structure was modeled Smiles: CC(O)COC(C)COC(C)COC(=O)c1c(Br)c(Br)c(Br)c(Br)c1C(=O)OCCOCCO

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Study type:

other: QSAR

Total exposure duration:

14 d

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

ca. 36.6 mg/kg soil ww

Nominal / measured:

estimated

Conc. based on:

other: component with smiles above

Basis for effect:

mortality

Validity criteria fulfilled:

not applicable

Conclusions:

Based on the QSAR estimate of one of the lower molecular weight components obtained with a valid structural group the LC50 for earthworms was predicted to be 36.6 mg/kg dry weight, indicating a low toxicity to earthworms. The component has a higher LC50 value than the lowest molecular weight component modeled as well and confirms that the former represents a worst case estimate of the toxicity of the UVCB components.
The Toolbox model predicts a lower toxicity than Epiwin and this value may be used as a worst case assumption. It is based on more molecules in the set of analogs, but the structural similarity is less pronounced.

Executive summary:

Testing an oligomeric mixture is technically difficult to impossible. Therefore the toxicity to earthworms was estimatet using an accepted QSAR calculation method. The model was OECD Toolbox version 4.2.

Based on the QSAR estimate of one of the lower molecular weight components obtained with a valid structural group the LC50 for earthworms was predicted to be 36.6 mg/kg dry weight, indicating a low toxicity to earthworms. The component has a slightly higher LC50 value than the lowest molecular weight component modeled as well and confirms that the former represents a worst case estimate of the toxicity of the UVCB components.

The Toolbox model predicts a lower toxicity than Epiwin and this value may be used as a worst case assumption. It is based on more molecules in the set of analogs, but the structural similarity is less pronounced.  

Reference 6

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

1. SOFTWARE OECD QSAR Toolbox

2. MODEL (incl. version number)OECD QSAR Toolbox
Version 4.2

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
SMILES: CC(O)COC(=O)c1c(Br)c(Br)c(Br)c(Br)c1C(=O)OCCOCCOC(=O)c1c(Br)c(Br)c(Br)c(Br)c1C(=O)OCC(C)O
4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL

See attached QRF
6. ADEQUACY OF THE RESULT .
The substance is included for illustrative purposes. It is already outside the applicability domain of the model with regard to the high estimated log Kow. This is consistent with the higher molecular weight of the 2-ring components and the assumed low bioavailability. 7 analogs are considered, R2 is 8.22 analogs are mostly esters.
The component modelled is par tof the two-ring fraction with one diethyleneglycol and two propyleneglycol units.

Principles of method if other than guideline:

- Software tool(s) used including version: OECD Toolbox version 4.2
- Model description: see Attached justification
- Justification of QSAR prediction: see Attached justification

GLP compliance:

no

Specific details on test material used for the study:

Here a 2-ring higher molecular weight component with smiles CC(O)COC(=O)c1c(Br)c(Br)c(Br)c(Br)c1C(=O)OCCOCCOC(=O)c1c(Br)c(Br)c(Br)c(Br)c1C(=O)OCC(C)O was modeled

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Study type:

other: QSAR

Total exposure duration:

14 d

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

ca. 227 000 mg/kg soil ww

Nominal / measured:

estimated

Conc. based on:

other: component with smiles above

Basis for effect:

mortality

Details on results:

The substance is outside of the applicability domain of the model, but is still relatively close to the reference chemicals and fits well into a linear extrapolation. The very high predicted LC50 value confirms the low bioavailability of the higher molecular weight oligomer fraction with the two aromatic rings and supports the asumption that the one ring fraction represents a worst case with regard to possible acute toxicity to terrestrial organisms.

Validity criteria fulfilled:

not applicable

Conclusions:

Based on the QSAR estimate of one of the higher molecular weight components obtained with a valid structural group the LC50 for earthworms was predicted to be 2.27 E+05 mg/kg dry weight, four orders of magnitude higher than the prediction for the lower molecular weigth components. Although the substance is outside of the applicability domain of the model ,it is still relatively close to the reference chemicals and fits well into a linear extrapolation. The very high predicted LC50 value confirms the low bioavailability of the higher molecular weight oligomer fraction with the two aromatic rings and supports the asumption that the one ring fraction represents a worst case with regard to possible acute toxicity to terrestrial organisms.

Executive summary:

Testing an oligomeric mixture is technically difficult to impossible. Therefore the toxicity to earthworms was estimatet using an accepted QSAR calculation method. The model was OECD Toolbox version 4.2. Based on the QSAR estimate of one of the higher molecular weight components obtained with a valid structural group the LC50 for earthworms was predicted to be  2.27 E+05 mg/kg dry weight, four orders of magnitude higher than the prediction for the lower molecular weigth components. Although the substance is outside of the applicability domain of the model ,it is still relatively close to the reference chemicals and fits well into a linear extrapolation. The very high predicted LC50 value confirms the low bioavailability of the higher molecular weight oligomer fraction with the two aromatic rings and supports the asumption that the one ring fraction represents a worst case with regard to possible acute toxicity to terrestrial organisms.

Reference 7

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

1. SOFTWARE OECD QSAR Toolbox

2. MODEL (incl. version number)OECD QSAR Toolbox
Version 4.2

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
SMILES:CC(O)COC(C)COC(=O)c1c(Br)c(Br)c(Br)c(Br)c1C(=O)OCCOCCOC(=O)c1c(Br)c(Br)c(Br)c(Br)c1C(=O)OCCOCCOC(=O)c1c(Br)c(Br)c(Br)
c(Br)c1C(=O)OCC(C)O
4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL

See attached QRF
6. ADEQUACY OF THE RESULT .
The substance is included for illustrative purposes. It is already outside the applicability domain of the model with regard to the high estimated log Kow. This is consistent with the higher molecular weight of the 2-ring components and the assumed low bioavailability. 7 analogs are considered, R2 is 8.22 analogs are mostly esters.
The component modelled is part of the two-ring fraction with two diethyleneglycol and three propyleneglycol units.

Principles of method if other than guideline:

- Software tool(s) used including version: OECD Toolbox version 4.2
- Model description: see Attached justification
- Justification of QSAR prediction: see Attached justification

GLP compliance:

no

Specific details on test material used for the study:

Here a higher molecular weight component with smiles CC(O)COC(C)COC(=O)c1c(Br)c(Br)c(Br)c(Br)c1C(=O)OCCOCCOC(=O)c1c(Br)c(Br)c(Br)c(Br
)c1C(=O)OCC(C)O was modeled

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Study type:

other: QSAR

Total exposure duration:

14 d

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

ca. 301 000 mg/kg soil ww

Nominal / measured:

estimated

Conc. based on:

other: component with smiles above

Basis for effect:

mortality

Details on results:

The substance is outside of the applicability domain of the model, but is still relatively close to the reference chemicals and fits well into a linear extrapolation. The very high predicted LC50 value confirms the low bioavailability of the higher molecular weight oligomer fraction with the two aromatic rings and supports the asumption that the one ring fraction represents a worst case with regard to possible acute toxicity to terrestrial organisms.

Validity criteria fulfilled:

not applicable

Conclusions:

Based on the QSAR estimate of one of the higher molecular weight components obtained with a valid structural group the LC50 for earthworms was predicted to be 3.01 E+05 mg/kg dry weight, four orders of magnitude higher than the prediction for the lower molecular weigth components. Although the substance is outside of the applicability domain of the model ,it is still relatively close to the reference chemicals and fits well into a linear extrapolation. The very high predicted LC50 value confirms the low bioavailability of the higher molecular weight oligomer fraction with the two aromatic rings and supports the asumption that the one ring fraction represents a worst case with regard to possible acute toxicity to terrestrial organisms.

Executive summary:

Testing an oligomeric mixture is technically difficult to impossible. Therefore the toxicity to earthworms was estimatet using an accepted QSAR calculation method. The model was OECD Toolbox version 4.2. Based on the QSAR estimate of one of the higher molecular weight components obtained with a valid structural group the LC50 for earthworms was predicted to be 3.01 E+05 mg/kg dry weight, four orders of magnitude higher than the prediction for the lower molecular weigth components. Although the substance is outside of the applicability domain of the model ,it is still relatively close to the reference chemicals and fits well into a linear extrapolation. The very high predicted LC50 value confirms the low bioavailability of the higher molecular weight oligomer fraction with the two aromatic rings and supports the asumption that the one ring fraction represents a worst case with regard to possible acute toxicity to terrestrial organisms.

Description of key information

Testing an oligomeric mixture is technically difficult to impossible. Therefore the toxicity to earthworms was estimatet using accepted QSAR calculation methods. Both the Epiwin model verion 4.1 and the OECD Toolbox version 4.2. were applied to the most suitable analogs. The lowest molecular weight component was used as the worst case estimate as this is supposed to have the highest bioavailability. This structure was within the applicability domain of the 2 models.

Based on the QSAR estimate of the lowest molecular weight component obtained with a valid structural group the lowest LC50 for earthworms was predicted to be 19 mg/kg dry weight with the OECD toolbox. This indicats a low toxicity to earthworms. The component represents a worst case estimate of the toxicity of the UVCB components.

The Toolbox model predicts a lower toxicity than Epiwin (2111 mg/kg soil dw) and this value may be used as a worst case assumption. It is based on more molecules in the set of analogs, but the structural simialrity is less pronounced.  Other components of the one ring fraction of oligomers showed higher LC50 values, but in the same order of magnitude.

Two 2 -ring oligomeric structures were also included for illustrative purposes and modeled using the OECD toolbox. Based on the QSAR estimate of the higher molecular weight components obtained with a valid structural group the LC50 for earthworms was predicted to be  2.27 E+05 and 3.01 E+05

mg/kg dry weight, four orders of magnitude higher than the prediction for the lower molecular weigth components. Although the substances were outside of the applicability domain of the model for log Kow, they are still relatively close to the reference chemicals and fit well into a linear extrapolation. The very high predicted LC50 value confirms the low bioavailability of the higher molecular weight oligomer fraction with the two aromatic rings and supports the asumption that the one ring fraction represents a worst case with regard to possible acute toxicity to terrestrial organisms. Modelling of the three ring fraction was also conducted, but the results were to far out of the applicability domain to be reported. However the predictions are far higher confirming again the low bioavailability of the higher molecular weight fractions.

Key value for chemical safety assessment

Short-term EC50 or LC50 for soil macroorganisms:

19 mg/kg soil dw