o-anisic acid

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data is from peer reviewed journal

Justification for type of information:

Data is from peer reviewed journal

Qualifier:

according to guideline

Guideline:

other: as mentioned below

Principles of method if other than guideline:

Biodegradation study was conducted for 5 days for evaluating the percentage biodegradability of test substance 2-methoxybenzoic acid. The study was performed using the standard iodometric titration method

GLP compliance:

not specified

Specific details on test material used for the study:

- Name of test material: 2-methoxybenzoic acid (2-MBA)
- Molecular formula: C8H8O3
- Molecular weight: 152.1482 g/mol
- Smiles notation: COc1ccccc1C(=O)O
- InChl:1S/C8H8O3/c1-11-7-5-3-2-4-6(7)8(9)10/h2-5H,1H3,(H,9,10)
- Substance type: Organic
- Physical state: Solid
- Other: Test chemical was of analytical and reagent grade.

Oxygen conditions:

not specified

Inoculum or test system:

other: River water

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Water samples were gathered from Jilin section in the Songhua river.

Duration of test (contact time):

5 d

Initial conc.:

2 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation:

other: BOD

Details on study design:

TEST CONDITIONS
- Composition of medium: The composition of the medium contained 3 g of beef extract, 10 g of peptone, 20 g of agar, and 1 L of distilled water.
- Test temperature: 20 ± 1°C
- pH: 7.4 to 7.6
- pH adjusted: yes
- Other: After the adjustment of pH of the medium, the culture was sterilized for 20 min at 1218C. One milliliter of diluted water sample was cultivated in 15 ml of the above medium at 31°C for 24 h, and the number of colonies was enumerated as the bacterial counts.

TEST SYSTEM
- Culturing apparatus: 250 ml BOD bottles
- Number of culture flasks/concentration: 2 replicates
- Test performed in closed vessels due to significant volatility of test substance: Test was performed in a 250 ml sealed BOD bottles.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes, inoculum blank was setup in 2 replicates.

STATISTICAL METHODS:
The total surface area of molecules, the heat of formation (Hf), and the energy of the highest occupied molecular orbital (EHOMO) of test chemical was calculated by the quantum chemical method Mopac Program. The linear regression analyses were performed with the SPSS® statistical package (Ver 10.0, SPSS, Chicago, IL, USA).

Key result

Remarks on result:

other: test chemical was considered to be easily degraded by river bacteria.

Details on results:

An obvious negative correlation apparently exists between Hf and K, that is, the lower the Hf value, the higher the K value, and thus based on this, test chemical was considered to be easily degraded by river bacteria.

Table: Structural parameters and biodegradation rates used in the study.

  

Compound	Hf (kj.M-1)	-Ehomo (eV)	TSA (A2)	pKa	Log Kow	K (d-1)
2-methoxybenzoic acid	-422.08	-9.68	171.54	4.08	1.70	1.06

 

Where,

Hf=heat of formation;

EHOMO=energy of highest occupied molecular orbital;

TSA=total surface area of molecule;

pKa=ionization constant;

KOW=n-octanol–water partition coefficient;

K=biodegradation rate constant.

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

Biodegradation study was conducted for 5 days for evaluating the percentage biodegradability of test substance 2-methoxybenzoic acid(CAS no. 579-75-9). The study was performed using the standard iodometric titration method using river water as a test inoculum. An obvious negative correlation apparently exists between Hf and K, that is, the lower the Hf value (-422.08 kj/M), the higher the K value (1.06/d), and thus based on this relationship, test chemical was considered to be easily degraded by river bacteria.

Executive summary:

Biodegradation study was conducted for 5 days for evaluating the percentage biodegradability of test substance 2-methoxybenzoic acid(CAS no. 579-75-9).The study was performed using the standard iodometric titration method. River water was used as a test inoculum obtained from Jilin section in the Songhua river. Temperature of the water sample was 15-20°C, pH 6.8 – 7.0 and dissolved oxygen was ranged between 7.8 – 9.0 mg/l, respectively. The bacterial counts were determined by standard plate count techniques and are about 1,200 to 3000 colony forming units/ml. Initial test substance conc. used in the study was 2 mg/l on the basis of ThOD. Residual DO of the test chemical was at least 1 mg/l at the final day. The test chemical was added to 250 ml BOD bottles. The composition ofthe medium contained 3 g of beef extract, 10 g of peptone, 20 g of agar, and 1 L of distilled water. After the adjustment of pH of the medium (pH 7.4-7.6), the culture was sterilized for 20 min at 1218C. One milliliter of diluted water sample was cultivated in 15 ml of the above medium at 31°C for 24 h, and the number of colonies was enumerated as the bacterial counts.The bottles were then filled to capacity with the water sample, sealed and incubated for 5 days at 20 ± 1°C.Two replicates were conducted for each chemical and each control (inoculum only).The DO concentrations were determined by the iodometric titration method.Biodegradability was assessed by measuring the BOD values in milligrams per liter (oxygen uptake values of test compound minus control).Biodegradability was expressed as the first-order kinetic rate constant (K) according to the traditional Monod equation (on the assumption that the bacterial counts were invariable during the experimental period).The total surface area of molecules, the heat of formation (Hf), and the energy of the highest occupied molecular orbital (EHOMO) of test chemical was calculated by the quantum chemical method Mopac Program. The linear regression analyses were performed with the SPSS®statistical package (Ver 10.0, SPSS, Chicago, IL, USA).An obvious negative correlation apparently exists between Hf and K,that is, the lower theHf value (-422.08 kj/M), the higher the K value (1.06/d), and thus based on this relationship, test chemical was considered to be readily biodegradable by river bacteria.

Description of key information

Biodegradation study was conducted for 5 days for evaluating the percentage biodegradability of test substance 2-methoxybenzoic acid(CAS no. 579-75-9)

(GUANG H. LU et. al, 2003).The study was performed using the standard iodometric titration method.River water was used as a test inoculum obtained fromJilin section in the Songhua river. Temperature of the water sample was 15-20°C, pH 6.8 – 7.0 and dissolved oxygen was ranged between 7.8 – 9.0 mg/l, respectively. The bacterial counts were determined by standard plate count techniques and are about 1,200 to 3000 colony forming units/ml. Initial test substance conc. used in the study was 2 mg/l on the basis of ThOD. Residual DO of the test chemical was at least 1 mg/l at the final day. The test chemical was added to 250 ml BOD bottles. The composition ofthe medium contained 3 g of beef extract, 10 g of peptone, 20 g of agar, and 1 L of distilled water. After the adjustment of pH of the medium (pH 7.4-7.6), the culture was sterilized for 20 min at 1218C. One milliliter of diluted water sample was cultivated in 15 ml of the above medium at 31°C for 24 h, and the number of colonies was enumerated as the bacterial counts.The bottles were then filled to capacity with the water sample, sealed and incubated for 5 days at 20 ± 1°C.Two replicates were conducted for each chemical and each control (inoculum only).The DO concentrations were determined by the iodometric titration method.Biodegradability was assessed by measuring the BOD values in milligrams per liter (oxygen uptake values of test compound minus control).Biodegradability was expressed as the first-order kinetic rate constant (K) according to the traditional Monod equation (on the assumption that the bacterial counts were invariable during the experimental period).The total surface area of molecules, the heat of formation (Hf), and the energy of the highest occupied molecular orbital (EHOMO) of test chemical was calculated by the quantum chemical method Mopac Program. The linear regression analyses were performed with the SPSS®statistical package (Ver 10.0, SPSS, Chicago, IL, USA).An obvious negative correlation apparently exists betweenHf andK,that is, the lower theHf value (-422.08 kj/M), the higher theKvalue (1.06/d), and thus based on this relationship, test chemical was considered to be readily biodegradable by river bacteria.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Various experimental study and supporting data for the target compound 2-methoxybenzoic acid(CAS No. 579-75-9) alongwith the supporting study for its closest read across substance with were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental key study from peer reviewed journal (GUANG H. LU et. al, 2003), biodegradation study was conducted for 5 days for evaluating the percentage biodegradability of test substance 2-methoxybenzoic acid (CAS no. 579-75-9).The study was performed using the standard iodometric titration method. River water was used as a test inoculum obtained from Jilin section in the Songhua river. Temperature of the water sample was 15-20°C, pH 6.8 – 7.0 and dissolved oxygen was ranged between 7.8 – 9.0 mg/l, respectively. The bacterial counts were determined by standard plate count techniques and are about 1,200 to 3000 colony forming units/ml. Initial test substance conc. used in the study was 2 mg/l on the basis of ThOD. Residual DO of the test chemical was at least 1 mg/l at the final day. The test chemical was added to 250 ml BOD bottles. The composition of the medium contained 3 g of beef extract, 10 g of peptone, 20 g of agar, and 1 L of distilled water. After the adjustment of pH of the medium (pH 7.4-7.6), the culture was sterilized for 20 min at 1218C. One milliliter of diluted water sample was cultivated in 15 ml of the above medium at 31°C for 24 h, and the number of colonies was enumerated as the bacterial counts. The bottles were then filled to capacity with the water sample, sealed and incubated for 5 days at 20 ± 1°C.Two replicates were conducted for each chemical and each control (inoculum only).The DO concentrations were determined by the iodometric titration method. Biodegradability was assessed by measuring the BOD values in milligrams per liter (oxygen uptake values of test compound minus control).Biodegradability was expressed as the first-order kinetic rate constant (K) according to the traditional Monod equation (on the assumption that the bacterial counts were invariable during the experimental period).The total surface area of molecules, the heat of formation (Hf), and the energy of the highest occupied molecular orbital (EHOMO) of test chemical was calculated by the quantum chemical method Mopac Program. The linear regression analyses were performed with the SPSS® statistical package (Ver 10.0, SPSS, Chicago, IL, USA).An obvious negative correlation apparently exists between Hf and K,that is, the lower the Hf value (-422.08 kj/M), the higher the K value (1.06/d), and thus based on this relationship, test chemical was considered to be readily biodegradable by river bacteria.

 

In a supporting data, biodegradation experiment was conducted for 5 days for evaluating the percentage biodegradability of test substance 2-methoxybenzoic acid (CAS no. 579-75-9) (G. H. Lu et. al, 2002).The study was performed using the standard iodometric titration method. River water was used as a test inoculum obtained from Jilin section in the Songhua river. Temperature of the water sample was 15-20°C, pH 6.8 – 7.0 and dissolved oxygen was about 8.0 mg/l, respectively. The bacterial counts were determined by standard plate count techniques and are about 800-3000/ml. Initial test substance conc. used in the study was 2 mg/l on the basis of ThOD. Residual DO of the test chemical was at least 1 mg/l at the final day. The test chemical was added to 150 ml of water sample in 250 ml BOD bottles. The bottles were then filled to capacity with the water sample, sealed and incubated for 5 days at 20 ± 1°C. The DO concentrations were determined by the iodometric titration method. The test result was expressed as BOD% by comparing the measured BOD5 with ThOD. Mw, Hf and Ehomo of test chemical was calculated by the quantum chemical method MOPAC 6.0-AMI on energy minimized structures. The percentage degradation of test substance was determined to be 55.8% by using BOD parameter in 5 days. Thus, based on percentage degradation, 2-methoxybenzoic acid is considered to be biodegradable in nature.

 

Another biodegradation study was conducted for 14 days for evaluating the percentage biodegradability of test substance 2-ethyl-9,10-anthraquinone (CAS no. 84-51-5) (GERHARD ZELLNER et. al, 1990). Micro-organisms (Desulfovibrio vulgaris Marburg, Desulfovibrio simplex" XVI and Desulfovibriosp. Strain MP47) was used as a test inoculum. Desulfovibrio vulgaris Marburg DSM 2119 was obtained from Hans Hippe, Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Braunschweig, Federal Republic of Germany. "Desulfovibrio simplex" XVI DSM 4141 and Desulfovibrio sp. strain MP47 were isolated from a laboratory digester for the biomethanation of whey. Desulfovibrio vulgaris Marburg, "Desulfovibrio simplex" XVI, and Desulfovibrio sp. Strain MP47 were routinely cultured in a medium that contained the following (per liter): 4.25 g of Na2SO4, 0.255 g of K2HPO4, 0.255 g of KH2PO4, 0.255 g of (NH4)2S04, 0.45 g of NaCl, 0.10 g of MgSO4 - 7H20, 2.0 g of yeast extract, 60 mg of CaCl2, 4 mg of FeSO4, 24 mg of Ni(NH4)2(SO4)2, and 1 mg of resazurin. The medium was supplemented with 10 ml each of vitamin and mineral solutions and reduced by the addition of 0.5 g of L-cysteine hydrochloride and 0.5 g of Na2S.9H20 per liter.Initial test substance conc. used in the study was 250 mg/20 ml.Parallel cultures in serum bottles containing 20 ml of medium and 250 mg of any one of the substrates mentioned above per liter were incubated under N2-CO2 (80:20%, 300 kPa) at 37°C on a shaker (100 rpm) for 4 weeks. Biotransformation of the substrates was analyzed by at least two methods, including HPLC with two detector systems, UV spectroscopy at 254 nm (293 nm for pyridoxal hydrochloride), and thin-layer chromatography.

Optical density of cultures was measured with a photometer (Stasar II; Gilford Instrument Laboratories, Inc., Oberlin, Ohio) at a wavelength of 578 nm. Samples were withdrawn from the serum bottles with a syringe, transferred into a quartz cuvette, and reduced with a grain of sodium dithionite. All growth measurements were carried out with the same cuvette and controlled by microscopic counting. Optical density measurements of parallel cultures were corrected for the absorbance measured immediately after inoculation and for the absorbance reached in control cultures in the absence of an added electron donor for sulfate reduction. As no growth of test organism was obtained using the test chemical as a substrate, no transformation of 2-methoxybenzoic acid was determined in 28 days. Thus, 2 -methoxybenzoic acid is considered to be not readily biodegradable in nature.

 

In a supporting study fromauthoritative database(J-CHECK, 2016) for read across substance o-acetylsalicylic acid (CAS no. 50-78-2),biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of read across substance o-acetylsalicylic acid. Concentration of inoculum i.e, sludge used was 30 mg/l and initial substance conc. used in the study was 100 mg/l, respectively. At the beginning of the test, the pH of the test solution was adjusted. The percentage degradation of read across substance was determined to be 86, 97 and 100% degradation by BOD, TOC removal and HPLC parameter in 28 days. The read across substance was hydrolyzed to form Salicylic acid and Acetic acid in (Water + Test Substance) systems. Thus, based on percentage degradation, o-acetylsalicylic acid is considered to be readily biodegradable in nature.

 

Although one study(GERHARD ZELLNER et. al, 1990)indicate that the chemical2-methoxybenzoic acid is not readily biodegradable, on the basis of overall reported results for target chemical 2-methoxybenzoic acid(from peer reviewed journal) and for its read across substance (from authoritative database J-CHECK), it can be concluded that the test substance 2-methoxybenzoic acid can be expected to be readily biodegradable in nature.