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Biodegradation in water: screening tests

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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:
not specified
Specific details on test material used for the study:
- Name of test material: 4-(phenylazo)benzene-1,3-diamine acetate
- IUPAC name: 4-(phenylazo)benzene-1,3-diamine acetate
- Molecular formula: C14H16N4O2
- Molecular weight: 272.306 g/mole
- Smiles : c1(ccc(c(N)c1)\N=N\c1ccccc1)N.C(C)(=O)O
- Inchl: 1S/C12H12N4.C2H4O2/c13-9-6-7-12(11(14)8-9)16-15-10-4-2-1-3-5-10;1-2(3)4/h1-8H,13-14H2;1H3,(H,3,4)/b16-15+;
- Substance type: Organic
- Physical state: Solid
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.
Parameter:
probability of ready biodegradability (QSAR/QSPR)
Remarks on result:
other: not readily biodegradable as estimated by BIOWIN model
Validity criteria fulfilled:
not specified
Interpretation of results:
not readily biodegradable
Conclusions:
The biodegradability of the test chemical 4-(phenylazo)benzene-1,3-diamine acetate] was calculated using seven different Biowin 1-7 models of the BIOWIN v4.10 software. The results indicate that the test chemical 4-(phenylazo)benzene-1,3-diamine acetate is expected to be not readily biodegradable.
Executive summary:

Estimation Programs Interface Suite (EPI suite, 2018) was run to predict the biodegradation potential of the test compound 4-(phenylazo)benzene-1,3-diamine acetate (CAS no. 79234 -33 -6) 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 Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical  4-(phenylazo)benzene-1,3-diamine acetate is expected to be not readily biodegradable.

Description of key information

Estimation Programs Interface Suite (EPI suite, 2018) was run to predict the biodegradation potential of the test compound4-(phenylazo)benzene-1,3-diamine acetate(CAS no. 79234 -33 -6) 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 Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical 4-(phenylazo)benzene-1,3-diamine acetateis 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 study for target chemical 4-(phenylazo)benzene-1,3-diamine acetate (CAS No. 79234 -33 -6) and experimental studies for its structurally similar read across chemicals have been reviewed for biodegradation in water endpoint and their results are summarized below

 

First study was predicted data study in this study the Estimation Programs Interface Suite (EPI suite, 2018) was run to predict the biodegradation potential of the test compound 4-(phenylazo)benzene-1,3-diamine acetate(CAS no. 79234 -33 -6) 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 Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical 4-(phenylazo)benzene-1,3-diamine acetate is expected to be not readily biodegradable.

 

Further, to support above predicted data experimental study was done from UERL lab in this study the biodegradation experiment was carried out 35-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the read across chemical 4-(phenylazo)benzene-1,3-

diamine, CAS No. 495-54-5. 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 4 mg/L, while that of inoculum was 32 ml/l. ThOD (Theoretical oxygen demand) of read across and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The BOD35 value of 4-(phenylazo)benzene-1,3-diamine, CAS No. 495-54-5 was observed to be 0.7 mgO2/mg. ThOD was calculated as 1.80 mgO2/mg. Accordingly, the % degradation of the test item after 35 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 38.88%. Based on the results, the read across chemical, under the test conditions, was considered to be not readily biodegradable over a period of 35 days.

 

 Next study was experimental study was reviewed from Water Research Journal in this study the Biodegradation experiment was conducted for 20 days for evaluating the percentage biodegradability of the substance 4-nitroaniline (CAS no. 100 -01 -6). Activated sludge was used as a test inoculum. Activated sludge taken from a sewage plant is cultivated in a 1000ml volumetric cylinder. The mixture is aerated with pressure air. Every day 200 ml of the mixture is driven off so that the sludge age is 5 days. The residue (200 ml of the thickened activated sludge) is diluted with tap water to the volume ofca.800 ml and 600 mg/l of starch or glucose, 600 mg/l of peptone, 25 ml of a phosphate buffer pH 7.2, and the solution of the tested compound are added. Then the mixture in the cylinder is made up to 1000ml with tap water and aerated for 23 h (the recirculation ratio is 0-25). After this period the procedure is repeated. The tested substance is dissolved in a beaker in a biological medium in a concentration corresponding to 200mg 1 -I COD. To the biological medium such amount of thickened adapted activated sludge is added to make dry matter of the inoculum 100mgl. The beaker is placed in a dark room with a roughly 3 constant temperature of 20 ± 3 °C on an electromagnetic stirrer. The initial value of COD or organic carbon of the liquid phase samples were determined. Samples filtered or centrifuged before analysis, are taken at suitable intervals. The decrease of the tested substance in the liquid phase is evaluated by determining COD or organic carbon. With the degree of degradation also the average specific rate of degradation is determined, expressed in terms of mg COD (or organic carbon) removed by a gramme of dry matter of the activated sludge per hour. The experiment is carried out till there is no decrease of COD. After that time the total percentage of COD removed and the rate of degradation are evaluated. Conc of test substance used for the study was 200mg/l, respectively. The percentage degradation of test substance was determined to be 0% by COD parameter in 20 days. Thus, based on percentage degradation, read across substance 4-nitroaniline was considered to be not readily biodegradable in nature.

 

On the basis of predicted data study for target chemical 4-(phenylazo)benzene-1,3-diamine acetate(CAS no. 79234 -33 -6) and experimental studies for its structurally similar read across chemical it can be concluded that test chemical is expected to be not readily biodegradable.