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Environmental fate & pathways

Endpoint summary

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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 1.1 days to > 1 yr, at pH range 4-9 and at a temperature of 50°C or 1.1 days, 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

28-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test item (Experimental study report., 2018). The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used as a test inoculum for the study.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. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 75.3%.  Degradation of Sodium Benzoate exceeds 46.38% on 7 days & 61.44% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 1.35 mgO2/mg. ThOD was calculated as 2.62 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 51.52%. Based on the results, the test item, under the test conditions, was considered to be inherently 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, 28.3% 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 0.134%), 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, 71.3% 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 endpoint is 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 microlitre of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 417.6 mg/l. The pH of test substance was 4.2. 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, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, Phenol, N,N-dimethylbenzamide, 3,5 -dinitrobenzamide, N-methylbenzamide, Benzamide, DDT having Koc value ranging from 1.25 to 5.63 . The Log Koc value of test chemical was determined to be 2.068 ± 0.007dimensionless at 25°C.This log Koc value indicates that the substance 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 half-life of the test chemical was determined. The study was performed according to OECD Guideline 111 (Hydrolysis as a Function of pH). Percentage degradation of test chemical was determined to be 3.91%, 1.085% and 4.78% at pH 4.0, 7.0 and 9.0 & at a temperature of 50°C, respectively and the half-life value of test chemical was determined to be > 1 yr. Since the chemical is not degradable less than 10 % in this test condition, it is presumably stable in water. Thus based on this, test chemical is considered to be stable in water.

 

In an another study the half-life value of test chemical was determined to be 1.1 days. Thus based on the value, test chemical is considered to undergo slow hydrolysis in water.

 

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 1.1 days to  > 1 yr, at pH range 4-9 and at a temperature of 50°C or 1.1 days, 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

28-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test item (Experimental study report., 2018). The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used as a test inoculum for the study.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. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 75.3%.  Degradation of Sodium Benzoate exceeds 46.38% on 7 days & 61.44% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 1.35 mgO2/mg. ThOD was calculated as 2.62 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 51.52%. Based on the results, the test item, under the test conditions, was considered to be inherently 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, 28.3% 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 0.134%), 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, 71.3% 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 ultimate inherently biodegradable in nature.

Bioaccumulation: aquatic / sediment

In accordance with column 2 of Annex IX of the REACH regulation, testing for this endpoint is 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 microlitre of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 417.6 mg/l. The pH of test substance was 4.2. 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, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, Phenol, N,N-dimethylbenzamide, 3,5 -dinitrobenzamide, N-methylbenzamide, Benzamide, DDT having Koc value ranging from 1.25 to 5.63 . The Log Koc value of test chemical was determined to be 2.068 ± 0.007dimensionless at 25°C.This log Koc value indicates that the substance has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.