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REACH

2',4',5',7'-tetrabromo-4,5,6,7-tetrachloro-3',6'-dihydroxyspiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one

EC number: 236-747-6 | CAS number: 13473-26-2

Life Cycle description
Uses advised against

Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Link to relevant study record(s)

Reference

Endpoint:: biodegradation in water: ready biodegradability
Type of information:: calculation (if not (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:: Data is from computational model developed by USEPA
Qualifier:: according to guideline
Guideline:: other: Modeling database
Principles of method if other than guideline:: The Biodegradation Probability Program (BIOWIN) estimates the probability for the rapid aerobic biodegradation of an organic chemical in the presence of mixed populations of environmental microorganisms .The model is part of the EpiSuite program of the US-EPA. Estimations are made with BIOWIN version 4.10. Estimates are based upon fragment constants that were developed using multiple linear and non-linear regression analyses. Experimental biodegradation data for the multiple linear and non-linear regressions were obtained from Syracuse Research Corporation's (SRC) data base of evaluated biodegradation data (Howard et. al., 1987). This version (v4.10) designates the models as follows (see also Boethling et al. 2003):
Biowin1 = linear probability model
Biowin2 = nonlinear probability model
Biowin3 = expert survey ultimate biodegradation model
Biowin4 = expert survey primary biodegradation model
Biowin5 = MITI linear model
Biowin6 = MITI nonlinear model
Biowin7 = anaerobic biodegradation model
GLP compliance:: no
Oxygen conditions:: other: aerobic (Biowin 1-6) and anaerobic (Biowin 7)
Inoculum or test system:: other: mixed populations of environmental microorganisms
Details on study design:: Using the computer tool BIOWIN v4.10 by US-EPA (EPIWIN) the aerobic as well as the anaerobic biodegradability of the test material can be estimated. The follwoing seven different models are used by the tool: Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI LInear Model, MITI Non-Linear Model and Anaerobic Model (calles Biowin 1-7, respectively). Due to this results the overall prediction of readily biodegradability is done for the desired chemical.

Biowin 1 and 2, are intended to convey a general indication of biodegradability under aerobic conditions, and not for any particular medium.
Biowin 1 (Linear model)
The fast biodegradation probability for any compound is calculated by summing, for all the fragments present in that compound, the fragment coefficient multiplied by the number of instances of the fragment in the compound (for MW, the value of that parameter is multiplied by its coefficient), and then adding this summation to the equation constant which is 0.7475. The summed values for each fragment coefficient multiplied by the number of instances appear in the "VALUE" column of the linear results screen.

Biowin 2 (Non-linear model)
Calculation of the fast biodegradation probability for any compound begins by summing, for all the fragments present in that compound, the fragment coefficient multiplied by the number of instances of the fragment in the compound (for MW, the value of that parameter is multiplied by its coefficient), then adding this summation to the equation constant which is 3.0087. The summed values for each fragment coefficient multiplied by the number of instances appear in the "VALUE" column of the non-linear results screen. The non-linear fast biodegradation probability is then calculated from the logistic equation as follows, where total = 3.0087 + the summation as described above:

Biowin 3 and 4 yield estimates for the time required to achieve complete ultimate and primary biodegradation in a typical or "evaluative" aquatic environment.

Biowin 5 and 6 are predictive models for assessing a compound’s biodegradability in the Japanese MITI (Ministry of International Trade and Industry) ready biodegradation test; i.e. OECD 301C. These models use an approach similar to that used to develop Biowin1 and 2. This protocol for determining ready biodegradability is among six officially approved as ready biodegradability test guidelines of the OECD (Organization for Economic Cooperation and Development). A total dataset of 884 chemicals was compiled to derive the fragment probability values that are applied in this MITI Biodegradability method. The dataset consists of 385 chemical that were critically evaluated as "readily degradable" and 499 chemicals that were critically evaluated as "not readily biodegradable".

Biowin 7, the anaerobic biodegradation model, is the most recent. As for the other Biowin models, multiple (linear) regression against molecular fragments was used to develop the model, which predicts probability of rapid degradation in the "serum bottle" anaerobic biodegradation screening test. This endpoint is assumed to be predictive of degradation in a typical anaerobic digester. Biowin7 estimates the probability of fast biodegradation under methanogenic anaerobic conditions; specifically, under the conditions of the "serum bottle" anaerobic biodegradation screening test (Meylan et al. 2007). A total of 169 compounds with serum bottle test data were identified for use in model development.

Out of seven different Biowin models, Biowin model 3 and 4 will help in estimating biodgeradability of the test chemical which was described as below-

Ultimate Biodegradation Timeframe and Primary Biodegradation Timeframe (Biowin 3 and 4)
These two models estimate the time required for "complete" ultimate and primary biodegradation. Primary biodegradation is the transformation of a parent compound to an initial metabolite. Ultimate biodegradation is the transformation of a parent compound to carbon dioxide and water, mineral oxides of any other elements present in the test compound, and new cell material. Then the rating was given to each model, which indicates the time required to achieve ultimate and primary biodegradation in a typical or "evaluative" aquatic environment. The ratings for each compound were averaged to obtain a single value for modeling. The ultimate or primary rating of a compound is calculated by summing, for all the fragments present in that compound.
: Key result
Remarks on result:: other: not readily biodegradable as estimated by BIOWIN model
Details on results:: Biowin1 (Linear Model Prediction) : Does not Biodegrade fast :-0.4438
Biowin2 (Non-Linear Model Prediction):Does not Biodegrade fast: 0.000
Biowin3 (Ultimate Biodegradation Timeframe): Recalcitrant: 0.0753
Biowin4 (Primary Biodegradation Timeframe): Recalcitrant : 1.6708
Biowin5 (MITI Linear Model Prediction) : Does not Biodegrade fast : -1.1820
Biowin6 (MITI Non-Linear Model Prediction): Does not Biodegrade fast : 0.0001
Biowin7 (Anaerobic Model Prediction): Does not Biodegrade fast : -0.7868
Ready Biodegradability Prediction: NO
Validity criteria fulfilled:: not specified
Interpretation of results:: not readily biodegradable
Conclusions:: The biodegradability of the test substance was calculated using seven different Biowin 1-7 models of the BIOWIN v4.10 software. The results indicate that the test substance was expected to be not readily biodegradable.
Executive summary:: Estimation Programs Interface Suite (EPI suite, 2017) BIOWIN v4.10 was run to predict the biodegradation potential of the test chemical in the presence of mixed populations of environmental microorganisms. The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that the test substance was expected to be not readily biodegradable.

Description of key information

The biodegradability of the test substance was calculated using seven different Biowin 1-7 models of the BIOWIN v4.10 software. The results indicate that the test substance was expected to be not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:: under test conditions no biodegradation observed

Additional information

Predicted data for the target compound and supporting weight of evidence studies for its read across substance from study report were reviewed for the biodegradation end point which is summarized as below:

Estimation Programs Interface Suite (EPI suite, 2017) BIOWIN v4.10 was run to predict the biodegradation potential of the test chemical in the presence of mixed populations of environmental microorganisms. The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that the test substance was expected to be not readily biodegradable.

In a supporting weight of evidence, Manometric respirometry test following the OECD guideline 301F was performed to determine the ready biodegradability of the test substance. The test system included control, test item and reference item. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 100mg/L, while that of inoculum was 10ml/l. ThOD (Theoretical oxygen demand) of test and reference substance was determined by calculation. % Degradation was calculated using the values of BOD and ThOD for test substance and reference substance. The BOD28 value of test substance was observed to be 0.058 mgO2/mg. ThOD was calculated as 0.709 mgO2/mg. Therefore, the % degradation of the test substance after 28 days of incubation at 20 ± 1°C was calculated to be 8.18%. Based on the results, the test substance, under the test conditions, was concluded to be non-biodegradable over a period of 28 days.

Another, 28-days Manometric respirometry test following the OECD guideline 301F to determine the ready biodegradability of the test chemical was conducted. The study was performed at a temperature of 20± 1°C. Mixture of domestic waste water, surface soil and soil samples was used as a test inoculum for the study. OECD mineral medium was used for the study. The test system included control, test and reference substance. The concentration of test and reference substance (Sodium Benzoate) chosen for both the study was 30mg/L, while that of inoculum was 10mg/L. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. The % degradation of procedure control (Sodium Benzoate) was determined to be 74.074%. The mean BOD value (mg O2/l) in control on 28th day was 9 mg O2/l. Degradation of Sodium Benzoate exceeds 50.050 % after 7 days and 68.068 % after 14 days. The BOD28 value of test chemical was observed to be -0.048mgO2sup>/mg. ThOD was calculated as 0.733 mgO2/mg. Accordingly, the % degradation of the test substance after 28 days of incubation at 20 ± 1°C was determined to be -6.496 %.Based on the results, the test substance under the test conditions, was considered to be not readily biodegradable.

On the basis of results of above mentioned studies for test chemical, it is concluded that the test chemical can be expected to be not readily biodegradable

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