2-ethoxybenzoic acid

Endpoint summary

Description of key information

Hydrolysis

On the basis of the experimental studies of the test chemical and applying the weight of evidence approach, the hydrolysis half-life value of the test chemical can be expected to be ranges from 6.3 days to 1.4 yrs, respectively. Thus, based on this half-life value, it can be concluded that the test chemical undergoes slow to negligible hydrolysis in water.

Biodegradation in water

Estimation Programs Interface Suite (2018) 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 chemical is expected to be readily biodegradable.

Biodegradation in water and sediment

Estimation Programs Interface (2018) prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 30% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of test chemical in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of test chemical in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.0797%), indicates that test chemical is not persistent in sediment.

Biodegradation in soil

The half-life period of test chemical in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (2018). If released into the environment, 69.3% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 30 days (720 hrs). Based on this half-life value of test chemical, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

Bioaccumulation: aquatic / sediment

In accordance with column 2 of Annex IX of the REACH regulation,testing for this endpointis scientifically not necessary and does not need to be conducted since the test chemical has a low potential for bioaccumulation based on logKow ≤ 3.

Adsorption / desorption

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals (Experimental study report, 2018). The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately pipetting 4 microliter of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 390 mg/l. The pH of test substance was 6.1. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances were Acetanilide, 4-chloroaniline, 4-methylaniline(p-Tolouidine), N-methylaniline, p-toluamide, Aniline, 2,5 -Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4-Nitrobenzamide, 1-naphthylamine, 1-naphtol, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichloro benzene, Pentachlorophenol, Phenol, N,N-dimethylbenzamide, 3,5-dinitrobenzamide, N-methylbenzamide, Benzamide, phenanthrene, DDT having Koc value ranging from 1.25 to 5.63. The Log Koc value of test chemical was determined to be 1.933 ± 0.000 at 25°C. This log Koc value indicates that the test chemical has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

Additional information

Hydrolysis

Data available for the test chemical has been reviewed to determine the half-life of hydrolysis as a function of pH. The studies are as mentioned below:

 

The hydrolysis half-life of the test chemical was determined. The study was performed at pH 3.5, 5.0, 7.4, 9.5 and 11.3 & at a temperature of 17⁰C, respectively. The half-life value of test chemical was determined to be 12.5 days, 5.4 days, 6.3 days, 2.2 days and 1.2 hrs with a corresponding hydrolysis rate constant of 0.00000065/sec, 0. 0000015/sec, 0. 0000013/sec, 0. 0000037/sec & 0. 00064/sec at pH 3.5, 5.0, 7.4, 9.5 and 11.3 & at a temperature of 17⁰C, respectively. Based on the half-life value (i.e, 6.3 days at pH 7.4), it is concluded that the test chemical is slowly hydrolysable in water.

 

In an another study, the half-life and base catalyzed second order hydrolysis rate constant was determined using a structure estimation method of the test chemical. The second order hydrolysis rate constant of test chemical was determined to be 0.16L/mol-sec with a corresponding half-lives of 1.4 yrs and 51 days at pH 7 and 8, respectively. Based on the half-life values, it is concluded that the test chemical is not hydrolysable.

 

For the test chemical, the hydrolysis half-life was determined. The study was performed at pH 5, 7 and 9, respectively. The half-life value of test chemical was determined to be > 30 days at pH 5, 7 and 9, respectively. Based on this half-life value, it is concluded that the test chemical is not hydrolysable.

 

On the basis of the experimental studies of the test chemical and applying the weight of evidence approach, the hydrolysis half-life value of the test chemical can be expected to be ranges from 6.3 days to 1.4 yrs, respectively. Thus, based on this half-life value, it can be concluded that the test chemical undergoes slow to negligible hydrolysis in water.

Biodegradation in water

Predicted data and various experimental studies of the test chemical were reviewed for the biodegradation end point which are summarized as below:

 

In a prediction using the Estimation Programs Interface Suite (2018), the biodegradation potential of the test chemical in the presence of mixed populations of environmental microorganisms was estimated. 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 test chemical is expected to be readily biodegradable.

 

In a supporting weight of evidence study from peer reviewed journal (Takashi Kameya et. al., 1995) for the test chemical,biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of test chemical by anaerobic bacteria as a test inoculum. Anaerobic bacteria was used as a test inoculum. The cultivated bacteria was prepared for seeding as follows. The bacteria suspension was drowned, homogenized, and separated with a centrifuge at 3000 rev./min for 10 min. The deposit was washed by the basal medium solution and separated again with a centrifuge. The deposit was dissolved again in the basal medium solution and its concentration was determined. This original suspension of bacteria was seeded in the test vials and its concentration was reconfirmed. The seeding bacteria had been cultured by a synthetic sewage in a continuous bioreactor at 37 + 1°C. 100 and 30 mg/l conc. was used for both inoculum and test substance conc., respectively. The test involve the use of 50 ml vials (total capacity: 68 ml). Ten test vials were prepared under the same conditions, and they were set in a water bath at 37°C ± 0.5”C. The original solution was added to the test inoculum and basal medium solution, which was prepared by organic medium and/or inorganic medium in oxygen-free water. At the starting time and after every week, two vials were opened simultaneously, and the concentration of organic compound was analyzed. The concentration of organic compound was determined by dissolved organic carbon (DOC) or chromatography. Biodegradation ratio is determined by analyzisng the decrease of DOC. The percentage degradation of the test chemical was determined to be 82% by DOC removal parameter in 14 days. Thus, based on the percentage degradation, the test chemical is considered to be readily biodegradable in nature.  

 

Another biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test chemical (J-CHECK, 2016). Concentration of inoculum i.e, sludge used was 30 mg/l and initial test 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 test chemical was determined to be 86, 97 and 100% degradation by BOD, TOC removal and HPLC parameter in 28 days. The test chemical was hydrolyzed to form salicylic acid and acetic acid in (Water + Test Substance) systems. Thus, based on percentage degradation, test chemical is considered to be readily biodegradable in nature.

 

For the test chemical, biodegradation study was conducted for evaluating the percentage biodegradability of test chemical (authoritative database Gsbl, 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 3 daysand 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 test chemical was determined to be 100% degradation by DOC removal parameter in 9 days. Thus, based on percentage degradation, test chemical is considered to be readily biodegradable in nature.

 

On the basis of above results for test chemical, it can be concluded that the test chemical can be expected to be readily biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface (2018) prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 30% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of test chemical in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of test chemical in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.0797%), indicates that test chemical is not persistent in sediment.

Biodegradation in soil

The half-life period of test chemical in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (2018). If released into the environment, 69.3% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 30 days (720 hrs). Based on this half-life value of test chemical, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

On the basis of available information, the test chemical can be considered to be readily biodegradable in nature.

Bioaccumulation: aquatic / sediment

In accordance with column 2 of Annex IX of the REACH regulation,testing for this endpointis scientifically not necessary and does not need to be conducted since the test chemical has a low potential for bioaccumulation based on logKow ≤ 3.

Adsorption / desorption

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals (Experimental study report, 2018). The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately pipetting 4 microliter of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 390 mg/l. The pH of test substance was 6.1. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances were Acetanilide, 4-chloroaniline, 4-methylaniline(p-Tolouidine), N-methylaniline, p-toluamide, Aniline, 2,5 -Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4-Nitrobenzamide, 1-naphthylamine, 1-naphtol, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichloro benzene, Pentachlorophenol, Phenol, N,N-dimethylbenzamide, 3,5-dinitrobenzamide, N-methylbenzamide, Benzamide, phenanthrene, DDT having Koc value ranging from 1.25 to 5.63. The Log Koc value of test chemical was determined to be 1.933 ± 0.000 at 25°C. This log Koc value indicates that the test chemical has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.