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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:
supporting study
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:
no guideline available
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 4.10Estimates 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 the test material: 4-methoxyphenylacetic acid
- Molecular formula: C9H10O3
- Molecular weight: 166.175 g/mol
- SMILES: c1(ccc(OC)cc1)CC(O)=O
- InChI: 1S/C9H10O3/c1-12-8-4-2-7(3-5-8)6-9(10)11/h2-5H,6H2,1H3,(H,10,11)
- 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
Duration of test (contact time):
3.064 wk
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.
Key result
Parameter:
other: Half-life
Value:
50
Sampling time:
3.064 wk
Remarks on result:
other: Other details not known
Details on results:
Biowin1 (Linear Model Prediction) : 0.9277: Biodegrades Fast
Biowin2 (Non-Linear Model Prediction): 0.9840: Biodegrades Fast
Biowin3 (Ultimate Biodegradation Timeframe): 3.0636: Weeks
Biowin4 (Primary Biodegradation Timeframe): 4.0021: Days
Biowin5 (MITI Linear Model Prediction) : 0.5717: Biodegrades Fast
Biowin6 (MITI Non-Linear Model Prediction): 0.6367: Biodegrades Fast
Biowin7 (Anaerobic Model Prediction): 0.6178: Biodegrades Fast
Ready Biodegradability Prediction: YES

BIOWIN (v4.10) Program Results:

==============================

SMILES : O=C(O)Cc(ccc(OC)c1)c1

CHEM : Benzeneacetic acid, 4-methoxy-

MOL FOR: C9 H10 O3

MOL WT : 166.18

--------------------------- BIOWIN v4.10 Results ----------------------------

Biowin1 (Linear Model Prediction) : Biodegrades Fast

Biowin2 (Non-Linear Model Prediction): Biodegrades Fast

Biowin3 (Ultimate Biodegradation Timeframe): Weeks

Biowin4 (Primary Biodegradation Timeframe): Days

Biowin5 (MITI Linear Model Prediction) : Biodegrades Fast

Biowin6 (MITI Non-Linear Model Prediction): Biodegrades Fast

Biowin7 (Anaerobic Model Prediction): Biodegrades Fast

Ready Biodegradability Prediction: YES

------+-----+--------------------------------------------+---------+---------

TYPE | NUM | Biowin1 FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+---------

Frag | 1 | Aliphatic acid [-C(=O)-OH] | 0.0727 | 0.0727

Frag | 1 | Aromatic ether [-O-aromatic carbon] | 0.1319 | 0.1319

Frag | 1 | Alkyl substituent on aromatic ring | 0.0547 | 0.0547

MolWt| * | Molecular Weight Parameter | | -0.0791

Const| * | Equation Constant | | 0.7475

============+============================================+=========+=========

RESULT | Biowin1 (Linear Biodeg Probability) | | 0.9277

============+============================================+=========+=========

------+-----+--------------------------------------------+---------+---------

TYPE | NUM | Biowin2 FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+---------

Frag | 1 | Aliphatic acid [-C(=O)-OH] | 0.6431 | 0.6431

Frag | 1 | Aromatic ether [-O-aromatic carbon] | 2.2483 | 2.2483

Frag | 1 | Alkyl substituent on aromatic ring | 0.5771 | 0.5771

MolWt| * | Molecular Weight Parameter | | -2.3597

============+============================================+=========+=========

RESULT | Biowin2 (Non-Linear Biodeg Probability) | | 0.9840

============+============================================+=========+=========

A Probability Greater Than or Equal to 0.5 indicates --> Biodegrades Fast

A Probability Less Than 0.5 indicates --> Does NOT Biodegrade Fast

------+-----+--------------------------------------------+---------+---------

TYPE | NUM | Biowin3 FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+---------

Frag | 1 | Aliphatic acid [-C(=O)-OH] | 0.3646 | 0.3646

Frag | 1 | Aromatic ether [-O-aromatic carbon] | -0.0581 | -0.0581

Frag | 1 | Alkyl substituent on aromatic ring | -0.0749 | -0.0749

MolWt| * | Molecular Weight Parameter | | -0.3672

Const| * | Equation Constant | | 3.1992

============+============================================+=========+=========

RESULT | Biowin3 (Survey Model - Ultimate Biodeg) | | 3.0636

============+============================================+=========+=========

------+-----+--------------------------------------------+---------+---------

TYPE | NUM | Biowin4 FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+---------

Frag | 1 | Aliphatic acid [-C(=O)-OH] | 0.3856 | 0.3856

Frag | 1 | Aromatic ether [-O-aromatic carbon] | 0.0771 | 0.0771

Frag | 1 | Alkyl substituent on aromatic ring | -0.0685 | -0.0685

MolWt| * | Molecular Weight Parameter | | -0.2398

Const| * | Equation Constant | | 3.8477

============+============================================+=========+=========

RESULT | Biowin4 (Survey Model - Primary Biodeg) | | 4.0021

============+============================================+=========+=========

Result Classification: 5.00 -> hours 4.00 -> days 3.00 -> weeks

(Primary & Ultimate) 2.00 -> months 1.00 -> longer

------+-----+--------------------------------------------+---------+---------

TYPE | NUM | Biowin5 FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+---------

Frag | 1 | Aliphatic acid [-C(=O)-OH] | 0.1812 | 0.1812

Frag | 1 | Aromatic ether [-O-aromatic carbon] | 0.1952 | 0.1952

Frag | 1 | Aromatic-CH2 | -0.0557 | -0.0557

Frag | 4 | Aromatic-H | 0.0082 | 0.0329

Frag | 1 | Methyl [-CH3] | 0.0004 | 0.0004

MolWt| * | Molecular Weight Parameter | | -0.4944

Const| * | Equation Constant | | 0.7121

============+============================================+=========+=========

RESULT | Biowin5 (MITI Linear Biodeg Probability) | | 0.5717

============+============================================+=========+=========

------+-----+--------------------------------------------+---------+---------

TYPE | NUM | Biowin6 FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+---------

Frag | 1 | Aliphatic acid [-C(=O)-OH] | 1.1346 | 1.1346

Frag | 1 | Aromatic ether [-O-aromatic carbon] | 1.3227 | 1.3227

Frag | 1 | Aromatic-CH2 | -0.1246 | -0.1246

Frag | 4 | Aromatic-H | 0.1201 | 0.4806

Frag | 1 | Methyl [-CH3] | 0.0194 | 0.0194

MolWt| * | Molecular Weight Parameter | | -4.7974

============+============================================+=========+=========

RESULT |Biowin6 (MITI Non-Linear Biodeg Probability)| | 0.6367

============+============================================+=========+=========

A Probability Greater Than or Equal to 0.5 indicates --> Readily Degradable

A Probability Less Than 0.5 indicates --> NOT Readily Degradable

------+-----+--------------------------------------------+---------+---------

TYPE | NUM | Biowin7 FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+---------

Frag | 1 | Aliphatic acid [-C(=O)-OH] | 0.1868 | 0.1868

Frag | 1 | Aromatic ether [-O-aromatic carbon] | 0.1780 | 0.1780

Frag | 1 | Alkyl substituent on aromatic ring | -0.1145 | -0.1145

Frag | 1 | Aromatic-CH2 | -0.0073 | -0.0073

Frag | 4 | Aromatic-H | -0.0954 | -0.3817

Frag | 1 | Methyl [-CH3] | -0.0796 | -0.0796

Const| * | Equation Constant | | 0.8361

============+============================================+=========+=========

RESULT | Biowin7 (Anaerobic Linear Biodeg Prob) | | 0.6178

============+============================================+=========+=========

A Probability Greater Than or Equal to 0.5 indicates --> Biodegrades Fast

A Probability Less Than 0.5 indicates --> Does NOT Biodegrade Fast

Ready Biodegradability Prediction: (YES or NO)

----------------------------------------------

Criteria for the YES or NO prediction: If the Biowin3 (ultimate survey

model) result is "weeks" or faster (i.e. "days", "days to weeks", or

"weeks" AND the Biowin5 (MITI linear model) probability is >= 0.5, then

the prediction is YES (readily biodegradable). If this condition is not

satisfied, the prediction is NO (not readily biodegradable). This method

is based on application of Bayesian analysis to ready biodegradation data

(see Help). Biowin5 and 6 also predict ready biodegradability, but for

degradation in the OECD301C test only; using data from the Chemicals

Evaluation and Research Institute Japan (CERIJ) database.

Validity criteria fulfilled:
not specified
Interpretation of results:
readily biodegradable
Conclusions:
The biodegradability of the substance was calculated using seven different Biowin 1-7 models of the BIOWIN v4.10 software. The results indicate that 4-Methoxyphenylacetic acid is expected to be readily biodegradable.
Executive summary:

Estimation Programs Interface Suite (EPI suite, 2017) was run to predict the biodegradation potential of the test compound 4-Methoxyphenylacetic acid (CAS no. 104 -01 -8) 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 4-Methoxyphenylacetic acid is expected to be readily biodegradable.

Description of key information

Biodegradation study was conducted for 20 days for evaluating the percentage biodegradability of test substance 4-Methoxyphenylacetic acid (CAS no. 104-01-8) (R. V. Subba-Rao and Martin Alexander, 1977). Bacteria was used as an inoculum. Microbial inoculum was isolated from Hudson Collamer silt loam. The test was performed under aerobic conditions at a temperature of 25ᵒC, respectively. The chemicals were introduced into the BOD bottles as sole carbon sources at a concentration of 2 mg of carbon per bottle. The compounds were added in acetone solutions, and the acetone was evaporated prior to the addition of O2-saturated water. Each bottle received 5 mg of Hudson Collamer silt loam as a source of the microbial inoculum. The bottles were filled with the air-saturated salts solution and closed with glass stoppers. Bottles containing O2 saturated water inoculated with soil (as a source of microbial inoculum) but no carbon source were also included in the study to account for the O2 depletion resulting from microbial oxidation of organic matter and ammonium. Test compound was also tested in combination with glucose (both at a conc. of 2 mg of carbon per bottle) to test whether the possible lack of biodegradation was a result of toxicity of the test chemical. Dissolved O2 in the bottles was measured at regular intervals using a Yellow Spring Instrument Co. oxygen analyzer, Model 53. The instrument was calibrated with the salts solution, the O2 content of which was determined by the Alsterberg modification of the Winkler method. At regular intervals, the dissolved O2 in the samples was measured after calibrating the instrument with a BOD bottle containing inoculated 02-saturated water supplemented with 0.1% KCN. The solutions in bottles showing O2 depletion were used to obtain microorganisms capable of utilizing the substrate. Based on appreciable degradation of test chemical after only a few days, 4 -Methoxyphenylacetic acid is considered to be biodegradable in nature.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

1 experimental study and predicted data for the test compound 4-Methoxyphenylacetic acid (CAS No. 104-01-8) and the 4 different studies for its closest read across substance using logkow as the primary descriptor were reviewed for the biodegradation endpoint which are summarized as below:

Study 1 - Biodegradation study was conducted for 20 days for evaluating the percentage biodegradability of test substance 4-Methoxyphenylacetic acid (CAS no. 104-01-8) (R. V. Subba-Rao and Martin Alexander, 1977). Bacteria was used as an inoculum. Microbial inoculum was isolated from Hudson Collamer silt loam. The test was performed under aerobic conditions at a temperature of 25ᵒC, respectively. The chemicals were introduced into the BOD bottles as sole carbon sources at a concentration of 2 mg of carbon per bottle. The compounds were added in acetone solutions, and the acetone was evaporated prior to the addition of O2-saturated water. Each bottle received 5 mg of Hudson Collamer silt loam as a source of the microbial inoculum. The bottles were filled with the air-saturated salts solution and closed with glass stoppers. Bottles containing O2 saturated water inoculated with soil (as a source of microbial inoculum) but no carbon source were also included in the study to account for the O2 depletion resulting from microbial oxidation of organic matter and ammonium. Test compound was also tested in combination with glucose (both at a conc. of 2 mg of carbon per bottle) to test whether the possible lack of biodegradation was a result of toxicity of the test chemical. Dissolved O2 in the bottles was measured at regular intervals using a Yellow Spring Instrument Co. oxygen analyzer, Model 53. The instrument was calibrated with the salts solution, the O2 content of which was determined by the Alsterberg modification of the Winkler method. At regular intervals, the dissolved O2 in the samples was measured after calibrating the instrument with a BOD bottle containing inoculated 02-saturated water supplemented with 0.1% KCN. The solutions in bottles showing O2 depletion were used to obtain microorganisms capable of utilizing the substrate. Based on appreciable degradation of test chemical after only a few days, 4 -Methoxyphenylacetic acid is considered to be biodegradable in nature.

 

Study 2 - Estimation Programs Interface Suite (EPI suite, 2017) was run to predict the biodegradation potential of the test compound 4-Methoxyphenylacetic acid (CAS no. 104 -01 -8) 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 4-Methoxyphenylacetic acid is expected to be readily biodegradable.

 

Study 3 - Biodegradation study was conducted for evaluating the percentage biodegradability of read across substance 4-ethoxybenzoic acid (CAS no. 619-86-3) (GSBL database, 2016). The study was performed according to OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test).The read across substances were prepared from stock solutions in added to such amounts that DOC concentrations of 50 – 400 mg/l or COD concentrations of 200 - 1000 mg/l were obtained. Duration of acclimatization phase (Time from test start to observable degradation) is 3 days and duration of the logarithmic degradation phase was 6 days. Activated sludge was used as an inoculum. The inoculum was extracted from the biological purification plant of the of HÖCHST 's work and is calculated in such a way that in the test batch 1.1 ± 0.1 g/l activated sludge dry substance (BTS) were included. The percentage degradation of read across substance was determined to be100% degradation by DOC removal parameter in 9 days. Thus, based on percentage degradation, 4-ethoxybenzoic acid is considered to be readily biodegradable in nature.

 

Study 4 - For read across chemical 4 -methoxybenzoic acid (CAS no. 100 -09 -4), biodegradation study was conducted for evaluating the percentage biodegradability of read across substance 4-methoxybenzoic acid (CAS no. 100-09-4)(GSBL database, 2016). The study was performed according to OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test).The test substances were prepared from stock solutions in added to such amounts that DOC concentrations of 50 – 400 mg/l or COD concentrations of 200 - 1000 mg/l were obtained. Duration of acclimatization phase (Time from test start to observable degradation) is 2 days and duration of the logarithmic degradation phase was 4 days. Activated sludge was used as an inoculum. The inoculum was extracted from the biological purification plant of the of HÖCHST’s work and is calculated in such a way that in the test batch 1.1 ± 0.1 g/l activated sludge dry substance (BTS) were included. The percentage degradation of read across substance was determined to be100% degradation by DOC removal parameter in 6 days. Thus, based on percentage degradation, 4-methoxybenzoic acid is considered to be readily biodegradable in nature.

 

Study 5 - In weight of evidence study of read across 4 -methoxybenzoic acid (CAS no. 100 -09 -4), biodegradation was conducted for 28 days for evaluating the percentage biodegradability of read across substance 4-methoxybenzoic acid (CAS no. 100-09-4) (GSBL database, 2016).  The study was performed according OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test) under aerobic conditions. The percentage degradation of read across substance was determined to be 100% degradation by DOC removal parameter in 6 days. Thus, based on percentage degradation, 4-methoxybenzoic acid is considered to be readily biodegradable in nature.

 

Study 6 - In another weight of evidence study of read across chemical 4 -methoxybenzoic acid (CAS no. 100 -09 -4), biodegradation was conducted for 28 days for evaluating the percentage biodegradability of read across substance 4-methoxybenzoic acid (CAS no. 100-09-4) (GSBL database, 2016). The study was performed according OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test).The percentage degradation of read across substance was determined to be 90% degradation by DOC removal parameter in 10 days. Thus, based on percentage degradation, 4-methoxybenzoic acid is considered to be readily biodegradable in nature.

 

On the basis of above results for target chemical (study 1 and 2) and its read across substance (study 3, 4, 5 and 6 from authoritative database), it can be concluded that the test substance 4-Methoxyphenylacetic acid can be expected to be readily biodegradable in nature.

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