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Environmental fate & pathways

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Description of key information

Hydrolysis

HYDROWIN v2.00 program of Estimation Programs Interface (2018) prediction model was used to determine the hydrolysis half-life of test chemical. The first order hydrolysis rate constant of test chemical was determined to be ranges from 0.000462 to 0.00657 per second with a corresponding half-lives of 1.76 to 25 mins at 25ᵒC, respectively.

Biodegradation in water

35-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test chemical (Experimental study report, 2019). 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 69.27%.  Degradation of Sodium Benzoate exceeds 63.25 % on 7 days & 69.27 % on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD35 value of test chemical was observed to be 0.75 mgO2/mg. ThOD was calculated as 1.69 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 44.37%. 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, 17.9% 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 37.5 days (900 hrs). The half-life (37.5 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 337.5 days (8100 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.528%), 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, 80.4% 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 75 days (1800 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

BCFBAF model of Estimation Programs Interface (2018) was used to predict the bioconcentration factor (BCF) of test chemical. The bioconcentration factor (BCF) of test chemical was estimated to be 241.9 L/kg whole body w.w (at 25 deg C) which does not exceed the bio concentration threshold of 2000, indicating that the test 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, 2018). 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 Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 4.7. 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 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-trichlorobenzene, 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 3.328 ± 0.001 dimensionless 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

HYDROWIN v2.00 program of Estimation Programs Interface (2018) prediction model was used to determine the hydrolysis half-life of test chemical. The first order hydrolysis rate constant of test chemical was determined to be ranges from 0.000462 to 0.00657 per second with a corresponding half-lives of 1.76 to 25 mins at 25ᵒC, respectively.

Biodegradation in water

35-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test chemical (Experimental study report, 2019). 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 69.27%.  Degradation of Sodium Benzoate exceeds 63.25 % on 7 days & 69.27 % on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD35 value of test chemical was observed to be 0.75 mgO2/mg. ThOD was calculated as 1.69 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 44.37%. 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, 17.9% 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 37.5 days (900 hrs). The half-life (37.5 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 337.5 days (8100 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.528%), 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, 80.4% 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 75 days (1800 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

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

 

In a prediction done using the BCFBAF Program of Estimation Programs Interface was used to predict the bioconcentration factor (BCF) of test chemical. The bioconcentration factor (BCF) of test chemical was estimated to be 241.9 L/kg whole body w.w (at 25 deg C) which does not exceed the bio concentration threshold of 2000, indicating that the test chemical is not expected to bioaccumulate in the food chain.

 

In an another prediction done by using Bio-concentration Factor module (ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017)), Bio-concentration Factor of the test chemical was estimated to be 164 at pH range 1-14, respectively. This value indicates that the test chemical was considered to be non-accumulative in aquatic organisms.

 

Bioconcentration Factor (BCF) of test chemical was estimated using Chemspider database (modelling database, 2017). The bioconcentration factor of test chemical was estimated to be 127.02 at pH both 5.5 and 7.4, respectively, which does not exceed the bioconcentration threshold of 2000, indicating that the test chemical is not expected to bioaccumulate in the food chain.

 

Another predicted data was estimated using SciFinder database (American Chemical Society (ACS), 2017) for predicting the bioconcentration factor (BCF) of test chemical. The bioconcentration factor (BCF) of test chemical was estimated to be 54.2 at pH range 1-10 respectively (at 25 deg C) which does not exceed the bio concentration threshold of 2000, indicating that the test chemical is not expected to bioaccumulate in the food chain.

 

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 chemical was estimated to be 21.6 dimensionless . The predicted BCF result based on the 5 OECD principles. Thus based on the result it is concluded that the test chemical is non-bioaccumulative in nature.

 

In a supporting weight of evidence study from authoritative database (2017), bioaccumulation experiment was conducted on test organism Cyprinus carpio for 28 days for evaluating the bioconcentration factor (BCF value) of test chemical. The study was performed according to "OECD Guideline 305 (Bioconcentration: Flow-through Fish Test)" and other guideline "Bioaccumulation test of a chemical substance in fish or shellfish" provided in "the Notice on the Test Method Concerning New Chemical Substances", respectively. Cyprinus carpio was used as a test organism for the study. Test chemical nominal conc. used for the study was 1mg/land 0.1 mg/l, respectively. Analytical method involve the recovery ratio: Fish : 87.5 %, - Limit of quantitation : Test water : 1st concentration area : 31 microg/L, 2nd concentration area : 3.1 microg/L, Fish : 340 ng/g. Range finding study involve the LC50 (96 h) 270 mg/l on Rice fish (Oryzias latipes). Lipid content of the test organism was determined to be 2.14% and 2.05% at the start and end of exposure. The bioconcentration factor (BCF value) of test chemical on Cyprinus carpio was determined to be ≤ 0.34 L/Kg at a conc. of 1 mg/l and ≤ 3.5 L/Kg at a conc. of 0.1 mg/l, respectively.

For the test chemical,bioaccumulation study was conducted on test organism Cyprinus carpio for 8 weeks for evaluating the bioconcentration factor (BCF value) of test chemical under static conditions (J-CHECK, 2017). The study was performed according to other guideline "Bioaccumulation test of a chemical substance in fish or shellfish" provided in "the Notice on the Test Method Concerning New Chemical Substances". Test chemical nominal conc. used for the study were 5 mg/l and 0.5 mg/l (w/v), respectively. Range finding study involve the TLm (48 hr) 610 mg/l on Rice fish (Oryzias latipes). The bioconcentration factor (BCF value) of test chemical on Cyprinus carpio was determined to be < 0.6 L/Kg at a conc. of 5 mg/l and < 6 L/Kg at a conc. of 0.5 mg/l, respectively.

 

On the basis of above results for test chemical, it can be concluded that the BCF value of test chemical was evaluated to be ranges from upto 241.9, respectively, which does not exceed the bioconcentration threshold of 2000, indicating that the test 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, 2018). 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 Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 4.7. 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 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-trichlorobenzene, 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 3.328 ± 0.001 dimensionless 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.