Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Hydrolysis

The hydrolysis rate constant and half-life of hydrolysis of test chemical was estimated by EPI Suite (HydroWin). The Hydrolysis rate constant estimated was 0.0465 L/mol/Sec at pH greater than 8. The Half-life at pH 8 estimated was 172.299 days and half-life at pH 7 estimated was 4.717 years. Since, half-life of hydrolysis of test chemical is very high, it shows negligible hydrolysis in water.

Biodegradation in water

35-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 for this 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 73.49 %. Degradation of Sodium Benzoate exceeds 39.15 % on 7 days & 70.48 % on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD35 value of test chemical was observed to be 1.17 mgO2/mg. ThOD was calculated as 2.47 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 47.36 %. Based on the results, the test item under the test conditions, was considered to be Ultimate inherent biodegradable in nature.

 

Biodegradation in water and sediment

Estimation Programs Interface (2017) prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 21.9% 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 test 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) but since the diffussion in the medium is less than 5% (reported as 3.09%), the substance is considered to be 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 (EPI suite, 2017). If released into the environment, 73.4 % 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 test chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

Bioaccumulation in aquatic and sediment

The BCFBAF Program of Estimation Programs Interface was used to predict the bioconcentration factor (BCF) of test chemical. From BCFBAF Program (v3.00) model of EPI suite the estimated bio concentration factor (BCF) for Test chemical is 158.7 L/kg wet-wt which does not exceed the bioconcentration threshold of 2000. Thus it is concluded that the test chemical is not expected to bio accumulate in the aquatic environment.

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, 2017). The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with ACN up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 5.7. 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 functional similarity with the test substance and calibration graph prepared. The reference substances were Benzoic acid methylester, Xylene, Ethylbenzene, Toluene, Naphthalene having Koc value ranging from 1.8 to 2.75. The Log Koc value of test chemical was determined to be 2.7284 ± 0.001 at 25°C. This log Koc value indicates that the test chemical has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.

Additional information

Hydrolysis

Predicted data for the test chemical and supporting experimental weight of evidence studies for its structurally similar read across substancewere reviewed for the hydrolysis end point which are summarized as below:

 

The hydrolysis rate constant and half-life of hydrolysis of test chemical was estimated by EPI Suite (HydroWin). The Hydrolysis rate constant estimated was 0.0465 L/mol/Sec at pH greater than 8. The Half-life at pH 8 estimated was 172.299 days and half-life at pH 7 estimated was 4.717 years. Since, half-life of hydrolysis of test chemical is very high, it shows negligible hydrolysis in water.

 

In other study, the test chemical showed half-life of 1.8 years at pH 8 and at temperature 10 degree C. Based on the half-life, the test chemical shows negligible hydrolysis.

                               

The half-life of the test chemical was determined using an estimated pseudo-first order hydrolysis rate constant of 0.00000021/sec. The half-life of test chemical was determined to be 38 days at pH 7 and a temperature of 25°C, 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 value was determined. 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.

 

On the basis of the available experimental studies, it can be concluded that the test chemical undergoes negligible hydrolysis in water.

Biodegradation in water

35-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 for this 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 73.49 %. Degradation of Sodium Benzoate exceeds 39.15 % on 7 days & 70.48 % on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD35 value of test chemical was observed to be 1.17 mgO2/mg. ThOD was calculated as 2.47 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 47.36 %. Based on the results, the test item under the test conditions, was considered to be Ultimate inherent biodegradable in nature.

 

Biodegradation in water and sediment

Estimation Programs Interface (2017) prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 21.9% 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 test 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) but since the diffussion in the medium is less than 5% (reported as 3.09%), the substance is considered to be 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 (EPI suite, 2017). If released into the environment, 73.4 % 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 test chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

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

Bioaccumulation in aquatic and sediment

Various predicted data for the test chemical and supportingweight of evidence studies for its structurally similar read across substancewere reviewed for the bioaccumulation end point which are summarized as below:

 

The BCFBAF Program of Estimation Programs Interface was used to predict the bioconcentration factor (BCF) of test chemical. From BCFBAF Program (v3.00) model of EPI suite the estimated bio concentration factor (BCF) for Test chemical is 158.7 L/kg wet-wt which does not exceed the bioconcentration threshold of 2000. Thus it is concluded that the test chemical is not expected to bio accumulate in the aquatic environment.

 

In another prediction done using Bio-concentration Factor (v12.1.0.50374)(ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017) module Bio-concentration Factor over the entire pH scale of the 2-phenylethyl benzoate estimated to be 947 dimensionless.

 

Another predicted data was estimated using Sci Finder database ( American Chemical Society (ACS), 2017) The Bioconcentration factor (BCF) for test chemical was predicted in aquatic organisms at pH 1-10 and temperature 25 °C was 775 dimensionless. .

 

From CompTox Chemistry Dashboard using OPERA (OPEn (quantitative) structure-activity Relationship Application)  V1.02 model in which calculation based on PaDEL descriptors (calculate molecular descriptors and fingerprints of chemical)  the bioaccumulation i.e BCF for test substance was estimated to be 8.23 dimensionless . 

 

Using Chemspider-ACD/Phychem suite prediction model the Bioconcentration factor (BCF) for test chemical was predicted in aquatic organisms was 575.03 dimensionless at pH 5.5 and pH 7.4. at temperature 25 deg C.

 

In a supporting study from authoritative database the BCF value for the test chemical was 62 dimensionless and it is predicted from regression derived equation and water solubility 59 mg/L.

 

In another supporting study from authoritative database the BCF value for test chemical was 46 dimensionless and it is estimated by using log Kow of 3.06 and regression derived equation.

 

On the basis of above results for test chemical (from EPI suite, ACD labs, SciFinder database, CompTox Chemistry Dashboard and ChemSpider,2017) and from authoritative database HSDB, it can be concluded that the BCF value of test substance ranges from 8.23– 947 which does not exceed the bioconcentration threshold of 2000, indicating that the chemical is not expected to bioaccumulate in the food chain.

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, 2017). The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with ACN up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 5.7. 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 functional similarity with the test substance and calibration graph prepared. The reference substances were Benzoic acid methylester, Xylene, Ethylbenzene, Toluene, Naphthalene having Koc value ranging from 1.8 to 2.75. The Log Koc value of test chemical was determined to be 2.7284 ± 0.001 at 25°C. This log Koc value indicates that the test chemical has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.