Registration Dossier

Administrative data

Endpoint:
biodegradation in soil: simulation testing
Type of information:
calculation (if not (Q)SAR)
Remarks:
calculation using EAWAG-BBD Pathway Prediction System
Adequacy of study:
weight of evidence
Study period:
2020
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a (Q)SAR model, with limited documentation / justification, but validity of model and reliability of prediction considered adequate based on a generally acknowledged source
Justification for type of information:
1. SOFTWARE

The EAWAG-BBD Pathway Prediction System predicts microbial catabolic reactions using substructure searching, a rule-base, and atom-to-atom mapping. The system is able to recognize organic functional groups found in a compound and predict transformations based on biotransformation rules. The biotransformation rules are based on reactions found in the EAWAG-BBD database or in the scientific literature.

2. MODEL
The pathway prediction system can be accessed at the EAWAG-BBD Pathway Prediction page, which can be reached from the "Pathway Prediction" link on the EAWAG-BBD home page, or by using the following URL: http://umbbd.ethz.ch/predict/.

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
Substance name: bis(2-ethylhexyl) tetrabromophthalate
Molecular formula: C24H34Br4O4
Molecular weight: 706.15 g/mol
Smiles notation: O=C(OCC(CCCC)CC)c(c(c(c(c1Br)Br)Br)C(=O)OCC(CCCC)CC)c1Br


4. SCIENTIFIC VALIDITY OF THE MODEL
- Defined endpoint:
likelyhood of reaction

1. Very likely reaction.
This is to be reserved for reactions that will almost certainly occur and occur with the highest priority. For example, if an acid chloride is generated, these compounds almost invariably undergo spontaneous hydrolysis in water very rapidly. So this would likely occur as the next step in any metabolic pathway in any bacterium. EAWAG-BBD btrule bt0026, Acid chloride -> Carboxylate is an example of this type of rule.
2. Likely reaction.
This is to be used when almost all bacteria can catalyze a given reaction with a functional group present in a molecule. For example, if the substrate has an ester linkage, it is often hydrolyzed by very common esterases, found both extracellularly and intracellularly. So giving an ester hydrolysis rule a score of 2 would give it a high priority but after an acid chloride hydrolysis reaction. You should also use 2 for a reaction that is significantly likely to occur once a certain intermediate has been generated. For example, aromatic ring cis-dihydrodiols are likely to be dehydrogenated to form catechols. Most organisms that make cis-dihydrodiols will also catalyze their dehydrogenation, thus the latter reaction is likely due to the linkage. EAWAG-BBD btrule bt0255, Dihydrodihydroxyaromatic -> 1,2-Dihydroxyaromatic is an example of this type of rule.
3. Possible reaction (neutral).
This applies to reactions that are common but not certain to occur in every system. For example, hydrocarbon oxygenation reactions are quite possible, but may or may not be likely to occur depending on what the substrate is. These must be looked at individually. Some may be likely, some may be possible and some may be unlikely based on current knowledge (an example of the latter may be oxygenases that work on 5-ring polycyclic aromatic hydrocarbons). EAWAG-BBD btrule bt0002, secondary Alcohol -> Ketone is an example of this type of rule.
4. Unlikely reaction.
This would be the case for reactions that clearly might occur, but are either very rarely catalyzed in bacterial and fungal populations, or that don't seem likely to occur because of the initial conditions we are using or other chemical/biochemical reason. EAWAG-BBD btrule bt0029, organoHalide -> RH, which is unlikely to occur under aerobic conditions, is an example of this type of rule.
5. Very unlikely reaction.
These reactions are ones, for example, that have never been observed under aerobic conditions and the enzymes are oxygen sensitive. Thus, given our initial conditions, we would expect that these reactions are highly unlikely. EAWAG-BBD btrule bt0270, Toluene -> Benzylsuccinate is an example of this type of rule.
6. No decision.

- unambigous algorithm:
The PPS predicts plausible pathways for microbial degradation of chemical compounds. Predictions use biotransformation rules, based on reactions found in the EAWAG-BBD database or in the scientific literature.

- Defined domain of applicability:
Chemicals that are out of the scope of the model
1. Readily Degraded and Selected Other Compounds
PPS predictions will terminate when they reach certain small, readily degraded compounds. If one of these is entered, its biodegradation will not be predicted, and, if possible, the user will be given a link to a KEGG pathway that includes this compound. These compounds also include dead-end compounds that are not degraded and accumulate in the environment. A list of termination compounds in the current system is available. The PPS will not display many small molecules with few or no carbon atoms, and certain common enzyme cofactors and derivates, produced in a prediction. This limits the list of predicted compounds to the more important ones.
2. Inorganic Chemicals
The rules used for the PPS were designed and developed for organic chemicals. Results for inorganic chemicals will be unreliable and their biodegradation should not be predicted using the PPS. This class of chemicals includes all chemicals that do not contain carbon. It includes neutral species such as titanium dioxide (TiO2) and inorganic salts, such as sodium chloride (NaCl) or potassium permanganate (KMnO4). This class of chemicals also includes organo-metallic chemicals (chemicals that contain carbon bonded to a metal species).
3. High Molecular Weight Compounds
Polymers and chemicals with a molecular weight greater than 1,000 should not have their biodegradation predicted as the PPS was not developed for these types of compounds. However, many polymers may be made up of dimers, trimers, and oligomers that have a molecular weight of less than 1,000. These smaller molecules may contain the same components as the larger polymers, and, therefore, could be run through the PPS. The results should be interpreted with due caution, however, as the biodegradation characteristics of chemicals with a molecular weight of >1,000 are likely to be significantly different from that of much smaller compounds, even if they have similar structures. This is due at least in part to the greatly reduced bioavailability of high molecular weight compounds.
4. Chemicals with Unknown or Variable Composition
The PPS was developed for discrete organic chemicals. That is, organic chemicals that can be represented by a single, precisely known chemical structure. If the compound has a variable composition (such as oligomers, natural fats, or a product mixture that changes composition depending on environmental conditions), a representative structure may be entered. However, in that case, it is possible that PPS results do not reflect the true nature of the biodegradation products.
5. Mixtures
Mixtures cannot be run through the PPS because it uses a single, discrete chemical structure as its input. If the chemical whose biodegradation you want to predict is a mixture of discrete organic substances, then each substance can be run through the PPS separately. Results should be interpreted with caution, as the biodegradation pathways predicted for substances separately will possibly be very different if they were degraded together.
6. Highly Fluorinated Compounds
Many highly fluorinated chemicals (those that have more fluorines than non-fluorine atoms bonded to carbon), including fully fluorinated organics (those that have all hydrogens on carbon replaced with fluorine), possess biodegradation properties that are vastly different than their non-substituted analogs. The rules used by the PPS do not accurately predict the unique characteristics of these materials. All per- and highly- fluorinated chemicals should not have their biodegradation predicted.

Reactions the EAWAG-PPS does not predict:
Some known environmental reactions are not predicted. Some reactions are too complex to predict. Important classes of these reactions contain, but are not limited to:

- Detoxification reactions. These include, but are not limited to, conjugation with xylose, glucuronate and sulfate.
- Dimerizations. These include, but are not limited to, disulfides formed from sulfide (-SH) groups, or azo compounds formed from primary amide (-NH2) groups.
- Methylation of hydroxyl groups.
- Acetylation of primary amines.
- Formation of intramolecular rings.
- Hydroxylation of aliphatic carbon atoms at positions where pure cultures of organisms that metabolize similar compounds do not hydroxylate, though environmental non-specific monooxygenases may.

- Mechanistic interpretation:
The EAWAG-BBD contains 332 biotransformation descriptions for 249 biotransformation rules. These include 46 descriptions (*) for 25 super rules, and 39 rules subsumed by them (status June 29, 2017). The reaction rules to be evaluated are considered for biodegradation under aerobic conditions, in soil (moderate moisture) or water, at neutral pH, 25°C, with no competing or toxic other compounds. Biotransformation rules are prioritized using a five-point Likkert scoring scale.

5. APPLICABILITY DOMAIN
The molecule is suitable for the model, as none of the criteria laid out for chemicals being out of scope are met.

5.1 Readily degraded and Selected other compunds:
The substance is not classified as readily biodegradable and does not meet the criteria for small molecules with few or no carbon atoms.
5.2 Inorganic Chemicals:
The substance is not classiefied as an inorganic chemical.
5.3 High molecular weight Compunds:
The substance has a weight < 1,000 g/mol and is well in the applicability domain of the model.
5.4 Chemicals with unknown or variable composition:
The substance is a mono-constitiuent substance.
5.5 Mixtures:
The substance is a mono-constituent substance.
5.6 Highly fluorinated compounds:
The substance does not contain any fluoro-groups.

6. ADEQUACY OF THE RESULT

6.1 Regulatory purpose:
The data may be used under any regulatory purpose.
6.2 Approach for regulatory interpretation of the model result:
If no experimental data are available, the estimated value may be used to fill data gaps needed for hazard and risk assessment. Further the value is used for other calculations.
6.3 Outcome:
The prediction of vapour pressure yields a useful result for further evaluation.
6.4 Conclusion:
The result is considered as useful for regulatory purposes.

Cross-referenceopen allclose all
Reason / purpose for cross-reference:
reference to other study
Reference
Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
aerobic
Inoculum or test system:
other: activated sludge (domestic and industrial)
Details on inoculum:
Activated sludge from an aeration tank of two different wastewater treatment plants treating predominantly domestic wastewater (Wupper area water authority, WWTP Odenthal and WWTP Cologne-Stammheim).
Activated sludge from the aeration tanks of a wastewater treatment plant treating predominantly wastewater of industrial origin (WWTP Leverkusen Bürrig).
The three sludge types were mixed taking 2 parts from each of the two domestic WWTPS plus 1 part from the industrial WWTP.
Pre-treatment of inoculum:
-The three sludges of two different origins were mixed as described before.
-The combined sludge was washed twice by adding mineral medium and centrifuging for 10 min at 2000 rpm and 20 °C and decanting off the supernatant.
-An aliquot of the wet sludge was dried in order to determine the wet weight / dry weight ratio of the sludge and to prepare a stock suspension with a defined concentration of suspended solids.
-The calculated amount of sludge, needed to achieve 300 mL of this stock suspension of 5 g dw/L, was dissolved in mineral medium and then filled up to a defined end volume.
-Before use, the inoculum was stored for one day at room temperature under continuous shaking with aeration.
Duration of test (contact time):
28 d
Initial conc.:
30 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Pre-treatment of the test item
7.5 mg of the test item were added to the test flasks, filled with 200 mL of mineral medium. Afterwards the volume was made up to 250 mL with mineral medium plus inoculum to give a final concentration of 30 mg test item/L and a final concentration of suspended solids of 100 mg/L.

A measured volume of inoculated mineral medium, containing a known concentration of 30 mg/L of the test item was stirred in a closed flask at a constant temperature (25 ± 2 °C) under aerobic conditions in the dark.
The consumption of oxygen (BOD) was determined by measuring the drop in pressure in the automated respirometer flasks. Evolved carbon dioxide was absorbed in sodium hydroxide. The amount of oxygen taken up by the test item (corrected for uptake by blank inoculum, run in parallel) was expressed as a percentage of the theoretical oxygen demand (ThOD).
The test lasted for 28 days.
The endogenous activity of the inoculum was checked running parallel blanks with inoculum but without test item. A reference compound (sodium benzoate) was run in parallel to check the operation of the procedures.
A toxicity control (test item and reference compound mixed) was not run in parallel, because the chosen concentration of the test item was not inhibitory to microorganisms (see study 2012/0061/07).
Because of the nature of biodegradation and of the mixed bacterial populations used as inoculum, determinations of test item and for the inoculum blank were carried out in triplicate and for the reference compound in duplicate.
The oxygen uptake was calculated from the readings taken at regular and frequent intervals, using the method given by the manufacturer of the equipment. At the end of incubation, the pH was measured in the flasks.
Reference substance:
benzoic acid, sodium salt
Remarks:
Purity: 99.7 %
Parameter:
% degradation (O2 consumption)
Value:
7
Sampling time:
28 d
Details on results:
6 % degradation after 7 days
7 % degradation after 14 days
6 % degradation after 21 days
7 % degradation after 28 days

pH after 28 days: 7.0 - 8.2
Parameter:
COD
Value:
1.337 other: mg O2/mg test mat.
Results with reference substance:
The per cent degradation of the reference compound sodium benzoate reached the level of ≥ 40 % after 7 days, but remained 2 % below the level of ≥ 65 % after 14 days, caused by high activity of the sludge in the blank control. As the degradation was above 40 % after 7 days (65% degradation on day 7) and the test item showed only 7 % biodegradation after 28 days, the test was regarded to be valid.
Validity criteria fulfilled:
yes
Remarks:
The degradation of the reference compound reached the level of ≥ 40 % after 7 days, but remained 2 % below the level of ≥ 65 % after 14 days.As the test item showed only 7 % biodegradation after 28 days, the test was regarded to be valid.
Interpretation of results:
not inherently biodegradable
Conclusions:
Within 28 days a degradation of 7 % was determined according to the OECD Guideline 302 C. Therefore the substance is considered to be "Not Inherently Biodegradable".
Executive summary:

To test for its inherent biodegradability potential, the substance was incubated for 28 days in continuously stirred 250 ml closed flask (three replicates) in the dark with an inoculum of mixed population of aquatic microorganisms (activated sludge) partially from domestic wastewater treatment plant and partially from industrial origin. In this assay, biodegradation was estimated by biological oxygen demand (BOD) over time. BOD was determined daily measuring the drop in pressure in the automated respirometer flasks. The incubation temperature was 25 ± 2 °C, pH was 7.0 - 8.2. The concentration of inoculum was 100 mg /L and the one of test substance was 30 mg/L. Degradation was calculated by subtracting the amount BOD in the negative (inoculum only) control from that in the test material or positive control at any given time point and divided by the chemical oxygen demand (COD) or theoretical oxygen demand (ThOD). The per cent degradation of the reference compound sodium benzoate reached the level of ≥ 40 % after 7 days, but remained 2 % below the level of ≥ 65 % after 14 days, caused by high activity of the sludge in the blank control. As the degradation was above 40 % after 7 days (65% degradation on day 7) and the test item showed only 7 % biodegradation after 28 days, the test was regarded to be valid. The test item is considered to be "Not Inherently Biodegradable".

Reason / purpose for cross-reference:
reference to other study
Reference
Endpoint:
biodegradation in water: sediment simulation testing
Type of information:
calculation (if not (Q)SAR)
Remarks:
calculation using EAWAG-BBD Pathway Prediction System
Adequacy of study:
weight of evidence
Study period:
2020
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a (Q)SAR model, with limited documentation / justification, but validity of model and reliability of prediction considered adequate based on a generally acknowledged source
Justification for type of information:
1. SOFTWARE
The EAWAG-BBD Pathway Prediction System predicts microbial catabolic reactions using substructure searching, a rule-base, and atom-to-atom mapping. The system is able to recognize organic functional groups found in a compound and predict transformations based on biotransformation rules. The biotransformation rules are based on reactions found in the EAWAG-BBD database or in the scientific literature.

2. MODEL
The pathway prediction system can be accessed at the EAWAG-BBD Pathway Prediction page, which can be reached from the "Pathway Prediction" link on the EAWAG-BBD home page, or by using the following URL: http://umbbd.ethz.ch/predict/.

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
Substance name: bis(2-ethylhexyl) tetrabromophthalate
Molecular formula: C24H34Br4O4
Molecular weight: 706.15 g/mol
Smiles notation: O=C(OCC(CCCC)CC)c(c(c(c(c1Br)Br)Br)C(=O)OCC(CCCC)CC)c1Br


4. SCIENTIFIC VALIDITY OF THE MODEL
- Defined endpoint:
likelyhood of reaction

1. Very likely reaction.
This is to be reserved for reactions that will almost certainly occur and occur with the highest priority. For example, if an acid chloride is generated, these compounds almost invariably undergo spontaneous hydrolysis in water very rapidly. So this would likely occur as the next step in any metabolic pathway in any bacterium. EAWAG-BBD btrule bt0026, Acid chloride -> Carboxylate is an example of this type of rule.
2. Likely reaction.
This is to be used when almost all bacteria can catalyze a given reaction with a functional group present in a molecule. For example, if the substrate has an ester linkage, it is often hydrolyzed by very common esterases, found both extracellularly and intracellularly. So giving an ester hydrolysis rule a score of 2 would give it a high priority but after an acid chloride hydrolysis reaction. You should also use 2 for a reaction that is significantly likely to occur once a certain intermediate has been generated. For example, aromatic ring cis-dihydrodiols are likely to be dehydrogenated to form catechols. Most organisms that make cis-dihydrodiols will also catalyze their dehydrogenation, thus the latter reaction is likely due to the linkage. EAWAG-BBD btrule bt0255, Dihydrodihydroxyaromatic -> 1,2-Dihydroxyaromatic is an example of this type of rule.
3. Possible reaction (neutral).
This applies to reactions that are common but not certain to occur in every system. For example, hydrocarbon oxygenation reactions are quite possible, but may or may not be likely to occur depending on what the substrate is. These must be looked at individually. Some may be likely, some may be possible and some may be unlikely based on current knowledge (an example of the latter may be oxygenases that work on 5-ring polycyclic aromatic hydrocarbons). EAWAG-BBD btrule bt0002, secondary Alcohol -> Ketone is an example of this type of rule.
4. Unlikely reaction.
This would be the case for reactions that clearly might occur, but are either very rarely catalyzed in bacterial and fungal populations, or that don't seem likely to occur because of the initial conditions we are using or other chemical/biochemical reason. EAWAG-BBD btrule bt0029, organoHalide -> RH, which is unlikely to occur under aerobic conditions, is an example of this type of rule.
5. Very unlikely reaction.
These reactions are ones, for example, that have never been observed under aerobic conditions and the enzymes are oxygen sensitive. Thus, given our initial conditions, we would expect that these reactions are highly unlikely. EAWAG-BBD btrule bt0270, Toluene -> Benzylsuccinate is an example of this type of rule.
6. No decision.

- unambigous algorithm:
The PPS predicts plausible pathways for microbial degradation of chemical compounds. Predictions use biotransformation rules, based on reactions found in the EAWAG-BBD database or in the scientific literature.

- Defined domain of applicability:
Chemicals that are out of the scope of the model
1. Readily Degraded and Selected Other Compounds
PPS predictions will terminate when they reach certain small, readily degraded compounds. If one of these is entered, its biodegradation will not be predicted, and, if possible, the user will be given a link to a KEGG pathway that includes this compound. These compounds also include dead-end compounds that are not degraded and accumulate in the environment. A list of termination compounds in the current system is available. The PPS will not display many small molecules with few or no carbon atoms, and certain common enzyme cofactors and derivates, produced in a prediction. This limits the list of predicted compounds to the more important ones.
2. Inorganic Chemicals
The rules used for the PPS were designed and developed for organic chemicals. Results for inorganic chemicals will be unreliable and their biodegradation should not be predicted using the PPS. This class of chemicals includes all chemicals that do not contain carbon. It includes neutral species such as titanium dioxide (TiO2) and inorganic salts, such as sodium chloride (NaCl) or potassium permanganate (KMnO4). This class of chemicals also includes organo-metallic chemicals (chemicals that contain carbon bonded to a metal species).
3. High Molecular Weight Compounds
Polymers and chemicals with a molecular weight greater than 1,000 should not have their biodegradation predicted as the PPS was not developed for these types of compounds. However, many polymers may be made up of dimers, trimers, and oligomers that have a molecular weight of less than 1,000. These smaller molecules may contain the same components as the larger polymers, and, therefore, could be run through the PPS. The results should be interpreted with due caution, however, as the biodegradation characteristics of chemicals with a molecular weight of >1,000 are likely to be significantly different from that of much smaller compounds, even if they have similar structures. This is due at least in part to the greatly reduced bioavailability of high molecular weight compounds.
4. Chemicals with Unknown or Variable Composition
The PPS was developed for discrete organic chemicals. That is, organic chemicals that can be represented by a single, precisely known chemical structure. If the compound has a variable composition (such as oligomers, natural fats, or a product mixture that changes composition depending on environmental conditions), a representative structure may be entered. However, in that case, it is possible that PPS results do not reflect the true nature of the biodegradation products.
5. Mixtures
Mixtures cannot be run through the PPS because it uses a single, discrete chemical structure as its input. If the chemical whose biodegradation you want to predict is a mixture of discrete organic substances, then each substance can be run through the PPS separately. Results should be interpreted with caution, as the biodegradation pathways predicted for substances separately will possibly be very different if they were degraded together.
6. Highly Fluorinated Compounds
Many highly fluorinated chemicals (those that have more fluorines than non-fluorine atoms bonded to carbon), including fully fluorinated organics (those that have all hydrogens on carbon replaced with fluorine), possess biodegradation properties that are vastly different than their non-substituted analogs. The rules used by the PPS do not accurately predict the unique characteristics of these materials. All per- and highly- fluorinated chemicals should not have their biodegradation predicted.

Reactions the EAWAG-PPS does not predict:
Some known environmental reactions are not predicted. Some reactions are too complex to predict. Important classes of these reactions contain, but are not limited to:

- Detoxification reactions. These include, but are not limited to, conjugation with xylose, glucuronate and sulfate.
- Dimerizations. These include, but are not limited to, disulfides formed from sulfide (-SH) groups, or azo compounds formed from primary amide (-NH2) groups.
- Methylation of hydroxyl groups.
- Acetylation of primary amines.
- Formation of intramolecular rings.
- Hydroxylation of aliphatic carbon atoms at positions where pure cultures of organisms that metabolize similar compounds do not hydroxylate, though environmental non-specific monooxygenases may.

- Mechanistic interpretation:
The EAWAG-BBD contains 332 biotransformation descriptions for 249 biotransformation rules. These include 46 descriptions (*) for 25 super rules, and 39 rules subsumed by them (status June 29, 2017). The reaction rules to be evaluated are considered for biodegradation under aerobic conditions, in soil (moderate moisture) or water, at neutral pH, 25°C, with no competing or toxic other compounds. Biotransformation rules are prioritized using a five-point Likkert scoring scale.

5. APPLICABILITY DOMAIN
The molecule is suitable for the model, as none of the criteria laid out for chemicals being out of scope are met.

5.1 Readily degraded and Selected other compunds:
The substance is not classified as readily biodegradable and does not meet the criteria for small molecules with few or no carbon atoms.
5.2 Inorganic Chemicals:
The substance is not classiefied as an inorganic chemical.
5.3 High molecular weight Compunds:
The substance has a weight < 1,000 g/mol and is well in the applicability domain of the model.
5.4 Chemicals with unknown or variable composition:
The substance is a mono-constitiuent substance.
5.5 Mixtures:
The substance is a mono-constituent substance.
5.6 Highly fluorinated compounds:
The substance does not contain any fluoro-groups.

6. ADEQUACY OF THE RESULT

6.1 Regulatory purpose:
The data may be used under any regulatory purpose.
6.2 Approach for regulatory interpretation of the model result:
If no experimental data are available, the estimated value may be used to fill data gaps needed for hazard and risk assessment. Further the value is used for other calculations.
6.3 Outcome:
The prediction of vapour pressure yields a useful result for further evaluation.
6.4 Conclusion:
The result is considered as useful for regulatory purposes.


Reason / purpose for cross-reference:
reference to other study
Reason / purpose for cross-reference:
reference to other study
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
Version / remarks:
2008; R. 6.1.8.6
Principles of method if other than guideline:
Gao J, Ellis LBM, Wackett LP (2010) "The University of Minnesota Biocatalysis/Biodegradation Database: improving public access" Nucleic Acids Research 38: D488-D491.
GLP compliance:
no
Specific details on test material used for the study:
Substance name: bis(2-ethylhexyl) tetrabromophthalate
Molecular formula: C24H34Br4O4
Molecular weight: 706.15 g/mol
Smiles notation: O=C(OCC(CCCC)CC)c(c(c(c(c1Br)Br)Br)C(=O)OCC(CCCC)CC)c1Br
Radiolabelling:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: EAWAG-PPS used
Remarks:
Standard conditions assumed for aerobic biotransformations are: exposed to air, in moist soil or water, at neutral pH, 25°C, with no competing or toxic other compounds.
Details on source and properties of sediment:
The reaction rules to be evaluated are considered for biodegradation under aerobic conditions, in soil (moderate moisture) or water, at neutral pH, 25°C.
Parameter followed for biodegradation estimation:
other: likelyhood of reaction
Details on study design:
EAWAG-BBD Pathway Prediction System (PPS)

1. Purpose and Scope
The PPS predicts plausible pathways for microbial degradation of chemical compounds. Predictions use biotransformation rules, based on reactions found in the EAWAG-BBD database or in the scientific literature.
PPS predictions are most accurate for compounds that are:
1.1. similar to compounds whose biodegradation pathways are reported in the scientific literature
1.2. in environments exposed to air, in moist soil or water, at moderate temperatures and pH, with no competing chemicals or toxins; and
1.3. the sole source of energy, carbon, nitrogen, or other essential element for the microbes in these environments, rather than present in trace amounts


2. Biotransformation Rules
The EAWAG-BBD contains 332 biotransformation descriptions for 249 biotransformation rules. These include 46 descriptions (*) for 25 super rules, and 39 rules subsumed by them (status June 29, 2017). The reaction rules to be evaluated are considered for biodegradation under aerobic conditions, in soil (moderate moisture) or water, at neutral pH, 25°C, with no competing or toxic other compounds. Biotransformation rules are prioritized using a five-point Likkert scoring scale; instructions for its use are:
1. Very likely reaction.
This is to be reserved for reactions that will almost certainly occur and occur with the highest priority. For example, if an acid chloride is generated, these compounds almost invariably undergo spontaneous hydrolysis in water very rapidly. So this would likely occur as the next step in any metabolic pathway in any bacterium. EAWAG-BBD btrule bt0026, Acid chloride -> Carboxylate is an example of this type of rule.
2. Likely reaction.
This is to be used when almost all bacteria can catalyze a given reaction with a functional group present in a molecule. For example, if the substrate has an ester linkage, it is often hydrolyzed by very common esterases, found both extracellularly and intracellularly. So giving an ester hydrolysis rule a score of 2 would give it a high priority but after an acid chloride hydrolysis reaction. You should also use 2 for a reaction that is significantly likely to occur once a certain intermediate has been generated. For example, aromatic ring cis-dihydrodiols are likely to be dehydrogenated to form catechols. Most organisms that make cis-dihydrodiols will also catalyze their dehydrogenation, thus the latter reaction is likely due to the linkage. EAWAG-BBD btrule bt0255, Dihydrodihydroxyaromatic -> 1,2-Dihydroxyaromatic is an example of this type of rule.
3. Possible reaction (neutral).
This applies to reactions that are common but not certain to occur in every system. For example, hydrocarbon oxygenation reactions are quite possible, but may or may not be likely to occur depending on what the substrate is. These must be looked at individually. Some may be likely, some may be possible and some may be unlikely based on current knowledge (an example of the latter may be oxygenases that work on 5-ring polycyclic aromatic hydrocarbons). EAWAG-BBD btrule bt0002, secondary Alcohol -> Ketone is an example of this type of rule.
4. Unlikely reaction.
This would be the case for reactions that clearly might occur, but are either very rarely catalyzed in bacterial and fungal populations, or that don't seem likely to occur because of the initial conditions we are using or other chemical/biochemical reason. EAWAG-BBD btrule bt0029, organoHalide -> RH, which is unlikely to occur under aerobic conditions, is an example of this type of rule.
5. Very unlikely reaction.
These reactions are ones, for example, that have never been observed under aerobic conditions and the enzymes are oxygen sensitive. Thus, given our initial conditions, we would expect that these reactions are highly unlikely. EAWAG-BBD btrule bt0270, Toluene -> Benzylsuccinate is an example of this type of rule.
6. No decision.
This is reserved for cases where you cannot assign a number for whatever reason.


3. Chemicals that are out of the scope of the model

3.1. Readily Degraded and Selected Other Compounds
PPS predictions will terminate when they reach certain small, readily degraded compounds. If one of these is entered, its biodegradation will not be predicted, and, if possible, the user will be given a link to a KEGG pathway that includes this compound. These compounds also include dead-end compounds that are not degraded and accumulate in the environment. A list of termination compounds in the current system is available. The PPS will not display many small molecules with few or no carbon atoms, and certain common enzyme cofactors and derivates, produced in a prediction. This limits the list of predicted compounds to the more important ones.
3.2. Inorganic Chemicals
The rules used for the PPS were designed and developed for organic chemicals. Results for inorganic chemicals will be unreliable and their biodegradation should not be predicted using the PPS. This class of chemicals includes all chemicals that do not contain carbon. It includes neutral species such as titanium dioxide (TiO2) and inorganic salts, such as sodium chloride (NaCl) or potassium permanganate (KMnO4). This class of chemicals also includes organo-metallic chemicals (chemicals that contain carbon bonded to a metal species).
3.3. High Molecular Weight Compounds
Polymers and chemicals with a molecular weight greater than 1,000 should not have their biodegradation predicted as the PPS was not developed for these types of compounds. However, many polymers may be made up of dimers, trimers, and oligomers that have a molecular weight of less than 1,000. These smaller molecules may contain the same components as the larger polymers, and, therefore, could be run through the PPS. The results should be interpreted with due caution, however, as the biodegradation characteristics of chemicals with a molecular weight of >1,000 are likely to be significantly different from that of much smaller compounds, even if they have similar structures. This is due at least in part to the greatly reduced bioavailability of high molecular weight compounds.
3.4. Chemicals with Unknown or Variable Composition
The PPS was developed for discrete organic chemicals. That is, organic chemicals that can be represented by a single, precisely known chemical structure. If the compound has a variable composition (such as oligomers, natural fats, or a product mixture that changes composition depending on environmental conditions), a representative structure may be entered. However, in that case, it is possible that PPS results do not reflect the true nature of the biodegradation products.
3.5. Mixtures
Mixtures cannot be run through the PPS because it uses a single, discrete chemical structure as its input. If the chemical whose biodegradation you want to predict is a mixture of discrete organic substances, then each substance can be run through the PPS separately. Results should be interpreted with caution, as the biodegradation pathways predicted for substances separately will possibly be very different if they were degraded together.
3.6. Highly Fluorinated Compounds
Many highly fluorinated chemicals (those that have more fluorines than non-fluorine atoms bonded to carbon), including fully fluorinated organics (those that have all hydrogens on carbon replaced with fluorine), possess biodegradation properties that are vastly different than their non-substituted analogs. The rules used by the PPS do not accurately predict the unique characteristics of these materials. All per- and highly- fluorinated chemicals should not have their biodegradation predicted.
Compartment:
natural sediment
Remarks on result:
not determinable
Parameter:
not specified
Remarks on result:
not determinable
Remarks:
calculation of likelyhood
Compartment:
natural sediment
Type:
not specified
Remarks on result:
not determinable
Remarks:
calculation of likelyhood
Transformation products:
not measured
Evaporation of parent compound:
no
Volatile metabolites:
not measured
Residues:
not measured
Details on results:
First transformation step
In a first transformation step the formed products are the corresponding alcohol and carboxylate. In this case, the product is (2-ethylhexyl) tetrabromophthalate the monoester of bis(2-ethylhexyl) tetrabromophthalate. This product was used as the starting point for the second transformation step.

Second transformation step
In the second transformation step two possible biotransformations were found, (bt0024) and (bt0001) both are considered as likely (score 2). One is the second saponification step from the monoester, (2-ethylhexyl) tetrabromophthalate, to tetrabromophtlalate and the corresponding alcohol. Oxidation of the alcohol to the corresponding aldehyde is handled by (bt0001)

First transformation step

In a first transformation step two different possible biotransformations were found. Both of these transformation processes (bt0024)  are considered as likely (score 2). This rule handles the saponification of esters and lactones. The formed products are the corresponding alcohol and carboxylate. In this case, the product is (2-ethylhexyl) tetrabromophthalate  the monoester of bis(2-ethylhexyl) tetrabromophthalate. This product was used as the starting point for the second transformation step.

Second transformation step

In the second transformation step two possible biotransformations were found, (bt0024) and (bt0001) both are considered as likely (score 2). Rule (bt0024) handles the second saponification step from the monoester, (2-ethylhexyl) tetrabromophthalate, to tetrabromophtlalate and the corresponding alcohol. Oxidation of the alcohol to the corresponding aldehyde is handled by (bt0001)

Validity criteria fulfilled:
not applicable
Conclusions:
Applying the EAWAG-BBD Pathway Prediction System (PPS) to the molecule “bis(2-ethylhexyl) tetrabromophthalate” yields valuable information about the putative environmental fate of the substance. From the amount of possible biotransformation processes not a single one could be found, which can be considered as very likely (score 1) to occur. For the applied molecule most of the possible aerobic biotransformations are rated likely (score 2) and only transformation path ways of third step are rated neutral (score 3). All anaerobic pathways are considered unlikely. The relevant arising transformation products are structurally very similar to the initial educt.
Taking this into account the obtained model data strongly point at a potential for biodegradation for “bis(2-ethylhexyl) tetrabromophthalate” CAS no.: 26040-51-7”.
Executive summary:

Applying the EAWAG-BBD Pathway Prediction System (PPS) to the molecule “bis(2-ethylhexyl) tetrabromophthalate” yields valuable information about the putative environmental fate of the substance. From the amount of possible biotransformation processes not a single one could be found, which can be considered as very likely (score 1) to occur. For the applied molecule most of the possible aerobic biotransformations are rated likely (score 2) and only transformation path ways of third step are rated neutral (score 3). All anaerobic pathways are considered unlikely. The relevant arising transformation products are (2-ethylhexyl) tetrabromophthalate and tetrabromophthalate. Furthermore, 2-ethylhexanol, and the subsequent oxidation products 2-ethylhexanal and 2-ethylhexanoic acid are formed. The transformation products are structurally very similar to the initial educt.

Taking this into account the obtained model data strongly point at a potential for biodegradation for “bis(2-ethylhexyl) tetrabromophthalate” CAS no.: 26040-51-7”.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2020
Report date:
2020

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
Version / remarks:
2008; R.6.1.8.6.
Principles of method if other than guideline:
Gao J, Ellis LBM, Wackett LP (2010) "The University of Minnesota Biocatalysis/Biodegradation Database: improving public access" Nucleic Acids Research 38: D488-D491.
GLP compliance:
no
Test type:
other: EAWAG-PPS used.

Test material

Constituent 1
Chemical structure
Reference substance name:
Bis(2-ethylhexyl) tetrabromophthalate
EC Number:
247-426-5
EC Name:
Bis(2-ethylhexyl) tetrabromophthalate
Cas Number:
26040-51-7
Molecular formula:
C24H34Br4O4
IUPAC Name:
1,2-bis(2-ethylhexyl) 3,4,5,6-tetrabromobenzene-1,2-dicarboxylate
Specific details on test material used for the study:
Substance name: bis(2-ethylhexyl) tetrabromophthalate
Molecular formula: C24H34Br4O4
Molecular weight: 706.15 g/mol
Smiles notation: O=C(OCC(CCCC)CC)c(c(c(c(c1Br)Br)Br)C(=O)OCC(CCCC)CC)c1Br

Study design

Oxygen conditions:
aerobic
Soil classification:
other: Standard conditions assumed for aerobic biotransformations are: exposed to air, in moist soil or water, at neutral pH, 25°C, with no competing or toxic other compounds.
Details on soil characteristics:
The reaction rules to be evaluated are considered for biodegradation under aerobic conditions, in soil (moderate moisture) or water, at neutral pH, 25°C.
Parameter followed for biodegradation estimation:
other: likelihood of reaction
Details on experimental conditions:
EAWAG-BBD Pathway Prediction System (PPS)

1. Purpose and Scope
The PPS predicts plausible pathways for microbial degradation of chemical compounds. Predictions use biotransformation rules, based on reactions found in the EAWAG-BBD database or in the scientific literature.
PPS predictions are most accurate for compounds that are:
1.1. similar to compounds whose biodegradation pathways are reported in the scientific literature
1.2. in environments exposed to air, in moist soil or water, at moderate temperatures and pH, with no competing chemicals or toxins; and
1.3. the sole source of energy, carbon, nitrogen, or other essential element for the microbes in these environments, rather than present in trace amounts


2. Biotransformation Rules
The EAWAG-BBD contains 332 biotransformation descriptions for 249 biotransformation rules. These include 46 descriptions (*) for 25 super rules, and 39 rules subsumed by them (status June 29, 2017). The reaction rules to be evaluated are considered for biodegradation under aerobic conditions, in soil (moderate moisture) or water, at neutral pH, 25°C, with no competing or toxic other compounds. Biotransformation rules are prioritized using a five-point Likkert scoring scale; instructions for its use are:
1. Very likely reaction.
This is to be reserved for reactions that will almost certainly occur and occur with the highest priority. For example, if an acid chloride is generated, these compounds almost invariably undergo spontaneous hydrolysis in water very rapidly. So this would likely occur as the next step in any metabolic pathway in any bacterium. EAWAG-BBD btrule bt0026, Acid chloride -> Carboxylate is an example of this type of rule.
2. Likely reaction.
This is to be used when almost all bacteria can catalyze a given reaction with a functional group present in a molecule. For example, if the substrate has an ester linkage, it is often hydrolyzed by very common esterases, found both extracellularly and intracellularly. So giving an ester hydrolysis rule a score of 2 would give it a high priority but after an acid chloride hydrolysis reaction. You should also use 2 for a reaction that is significantly likely to occur once a certain intermediate has been generated. For example, aromatic ring cis-dihydrodiols are likely to be dehydrogenated to form catechols. Most organisms that make cis-dihydrodiols will also catalyze their dehydrogenation, thus the latter reaction is likely due to the linkage. EAWAG-BBD btrule bt0255, Dihydrodihydroxyaromatic -> 1,2-Dihydroxyaromatic is an example of this type of rule.
3. Possible reaction (neutral).
This applies to reactions that are common but not certain to occur in every system. For example, hydrocarbon oxygenation reactions are quite possible, but may or may not be likely to occur depending on what the substrate is. These must be looked at individually. Some may be likely, some may be possible and some may be unlikely based on current knowledge (an example of the latter may be oxygenases that work on 5-ring polycyclic aromatic hydrocarbons). EAWAG-BBD btrule bt0002, secondary Alcohol -> Ketone is an example of this type of rule.
4. Unlikely reaction.
This would be the case for reactions that clearly might occur, but are either very rarely catalyzed in bacterial and fungal populations, or that don't seem likely to occur because of the initial conditions we are using or other chemical/biochemical reason. EAWAG-BBD btrule bt0029, organoHalide -> RH, which is unlikely to occur under aerobic conditions, is an example of this type of rule.
5. Very unlikely reaction.
These reactions are ones, for example, that have never been observed under aerobic conditions and the enzymes are oxygen sensitive. Thus, given our initial conditions, we would expect that these reactions are highly unlikely. EAWAG-BBD btrule bt0270, Toluene -> Benzylsuccinate is an example of this type of rule.
6. No decision.
This is reserved for cases where you cannot assign a number for whatever reason.


3. Chemicals that are out of the scope of the model

3.1. Readily Degraded and Selected Other Compounds
PPS predictions will terminate when they reach certain small, readily degraded compounds. If one of these is entered, its biodegradation will not be predicted, and, if possible, the user will be given a link to a KEGG pathway that includes this compound. These compounds also include dead-end compounds that are not degraded and accumulate in the environment. A list of termination compounds in the current system is available. The PPS will not display many small molecules with few or no carbon atoms, and certain common enzyme cofactors and derivates, produced in a prediction. This limits the list of predicted compounds to the more important ones.
3.2. Inorganic Chemicals
The rules used for the PPS were designed and developed for organic chemicals. Results for inorganic chemicals will be unreliable and their biodegradation should not be predicted using the PPS. This class of chemicals includes all chemicals that do not contain carbon. It includes neutral species such as titanium dioxide (TiO2) and inorganic salts, such as sodium chloride (NaCl) or potassium permanganate (KMnO4). This class of chemicals also includes organo-metallic chemicals (chemicals that contain carbon bonded to a metal species).
3.3. High Molecular Weight Compounds
Polymers and chemicals with a molecular weight greater than 1,000 should not have their biodegradation predicted as the PPS was not developed for these types of compounds. However, many polymers may be made up of dimers, trimers, and oligomers that have a molecular weight of less than 1,000. These smaller molecules may contain the same components as the larger polymers, and, therefore, could be run through the PPS. The results should be interpreted with due caution, however, as the biodegradation characteristics of chemicals with a molecular weight of >1,000 are likely to be significantly different from that of much smaller compounds, even if they have similar structures. This is due at least in part to the greatly reduced bioavailability of high molecular weight compounds.
3.4. Chemicals with Unknown or Variable Composition
The PPS was developed for discrete organic chemicals. That is, organic chemicals that can be represented by a single, precisely known chemical structure. If the compound has a variable composition (such as oligomers, natural fats, or a product mixture that changes composition depending on environmental conditions), a representative structure may be entered. However, in that case, it is possible that PPS results do not reflect the true nature of the biodegradation products.
3.5. Mixtures
Mixtures cannot be run through the PPS because it uses a single, discrete chemical structure as its input. If the chemical whose biodegradation you want to predict is a mixture of discrete organic substances, then each substance can be run through the PPS separately. Results should be interpreted with caution, as the biodegradation pathways predicted for substances separately will possibly be very different if they were degraded together.
3.6. Highly Fluorinated Compounds
Many highly fluorinated chemicals (those that have more fluorines than non-fluorine atoms bonded to carbon), including fully fluorinated organics (those that have all hydrogens on carbon replaced with fluorine), possess biodegradation properties that are vastly different than their non-substituted analogs. The rules used by the PPS do not accurately predict the unique characteristics of these materials. All per- and highly- fluorinated chemicals should not have their biodegradation predicted.

Results and discussion

Half-life / dissipation time of parent compound
Key result
Soil No.:
#1
DT50:
> 1 s
Type:
other: likelyhood of reaction
Temp.:
25 °C
Remarks on result:
other: estimated by Likkert Scale
Transformation products:
not measured
Evaporation of parent compound:
not specified
Details on results:
First transformation step
In a first transformation step the formed products are the corresponding alcohol and carboxylate. In this case, the product is (2-ethylhexyl) tetrabromophthalate the monoester of bis(2-ethylhexyl) tetrabromophthalate. This product was used as the starting point for the second transformation step.

Second transformation step
In the second transformation step two possible biotransformations were found, (bt0024) and (bt0001) both are considered as likely (score 2). One is the second saponification step from the monoester, (2-ethylhexyl) tetrabromophthalate, to tetrabromophtlalate and the corresponding alcohol. Oxidation of the alcohol to the corresponding aldehyde is handled by (bt0001)

Any other information on results incl. tables

First transformation step

In a first transformation step two different possible biotransformations were found. Both of these transformation processes (bt0024)  are considered as likely (score 2). This rule handles the saponification of esters and lactones. The formed products are the corresponding alcohol and carboxylate. In this case, the product is (2-ethylhexyl) tetrabromophthalate  the monoester of bis(2-ethylhexyl) tetrabromophthalate. This product was used as the starting point for the second transformation step.

Second transformation step

In the second transformation step two possible biotransformations were found, (bt0024) and (bt0001) both are considered as likely (score 2). Rule (bt0024) handles the second saponification step from the monoester, (2-ethylhexyl) tetrabromophthalate, to tetrabromophtlalate and the corresponding alcohol. Oxidation of the alcohol to the corresponding aldehyde is handled by (bt0001)

Applicant's summary and conclusion

Conclusions:
Applying the EAWAG-BBD Pathway Prediction System (PPS) to the molecule “bis(2-ethylhexyl) tetrabromophthalate” yields valuable information about the putative environmental fate of the substance. From the amount of possible biotransformation processes not a single one could be found, which can be considered as very likely (score 1) to occur. For the applied molecule most of the possible aerobic biotransformations are rated likely (score 2) and only transformation path ways of third step are rated neutral (score 3). All anaerobic pathways are considered unlikely. The relevant arising transformation products are structurally very similar to the initial educt.
Taking this into account the obtained model data strongly point at a potential for biodegradation for “bis(2-ethylhexyl) tetrabromophthalate” CAS no.: 26040-51-7”.
Executive summary:

Applying the EAWAG-BBD Pathway Prediction System (PPS) to the molecule “bis(2-ethylhexyl) tetrabromophthalate” yields valuable information about the putative environmental fate of the substance. From the amount of possible biotransformation processes not a single one could be found, which can be considered as very likely (score 1) to occur. For the applied molecule most of the possible aerobic biotransformations are rated likely (score 2) and only transformation path ways of third step are rated neutral (score 3). All anaerobic pathways are considered unlikely. The relevant arising transformation products are structurally very similar to the initial educt. The relevant arising transformation products are (2-ethylhexyl) tetrabromophthalate and tetrabromophthalate. Furthermore, 2-ethylhexanol, and the subsequent oxidation products 2-ethylhexanal and 2-ethylhexanoic acid are formed. The transformation products are structurally very similar to the initial educt.

Taking this into account the obtained model data strongly point at a potential for biodegradation for “bis(2-ethylhexyl) tetrabromophthalate” CAS no.: 26040-51-7”.