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Description of key information

Hydrolysis

On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach, the hydrolysis half-life value of the test chemical can be expected to be 3.3 yrs & 121 days with a hydrolysis rate constant of 0.063L/mol-sec or 2.1 yrs & 78 days with a hydrolysis rate constant of 0.10L/mol-sec at pH 7 and 8, respectively. Thus, based on this half-life value, it can be concluded that the test chemical can be expected to be not hydrolysable.

Biodegradation in water

28-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test chemical (Experimental study report, 2017). 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. 1 polyseed capsule were added in 500 ml D.I water and then stirred for 1 hour for proper mixing and functioning of inoculum. This gave the bacterial count as 107 to 108 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism.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% at 20 ± 1°C. Degradation of Sodium Benzoate exceeds 43.37% on 7th days & 58.43% on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 1.25 mgO2/mg. ThOD was calculated as 2.53 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 49.4%. Based on the results, the test item, under the test conditions, was considered to be ultimate inherently biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 24.9% 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 8.66 days (208 hrs). The half-life (8.66 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 77.916 days (1870 hrs). Based on this half-life value, it 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. If released into the environment, 71.1% 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 17.33 days ( 416 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 (v3.01) 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 22.95 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. The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately measuring 4μL of test item and diluted with acetonitrile up to 10 ml. Thus, the test solution concentration was 396 mg/l. The pH of test substance was 6.5. 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 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,Ndimethylbenzamide, 3,5-dinitrobenzamide, N-methylbenzamide, Benzamide, phenanthrene, DDT, Acetanilide having Koc value ranging from 1.25 to 5.63. The Log Koc value of test chemical was determined to be 3.698 ± 0.000 at 25°C. This log Koc value indicates that the test chemical has a strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.

Additional information

Hydrolysis

Data available for the structurally and functionally similar read across chemicals has been reviewed to determine the half-life of the test chemical. The studies are as mentioned below:

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 substance was determined to be 0.063L/mol-sec with a corresponding half-lives of 3.3 yrs and 121 days at pH 7 and 8, respectively. Based on the half-life values, it is concluded that test chemical is not hydrolysable.

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 substance was determined to be 0.10L/mol-sec with a corresponding half-lives of 2.1 yrs and 78 days at pH 7 and 8, respectively. Based on the half-life values, it is concluded that test chemical is not hydrolysable.

On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach, the hydrolysis half-life value of the test chemical can be expected to be 3.3 yrs & 121 days with a hydrolysis rate constant of 0.063L/mol-sec or 2.1 yrs & 78 days with a hydrolysis rate constant of 0.10L/mol-sec at pH 7 and 8, respectively. Thus, based on this half-life value, it can be concluded that the test chemical can be expected to be not hydrolysable.

Biodegradation in water

28-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test chemical (Experimental study report, 2017). 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. 1 polyseed capsule were added in 500 ml D.I water and then stirred for 1 hour for proper mixing and functioning of inoculum. This gave the bacterial count as 107 to 108 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism.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% at 20 ± 1°C. Degradation of Sodium Benzoate exceeds 43.37% on 7th days & 58.43% on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 1.25 mgO2/mg. ThOD was calculated as 2.53 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 49.4%. Based on the results, the test item, under the test conditions, was considered to be ultimate inherently biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 24.9% 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 8.66 days (208 hrs). The half-life (8.66 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 77.916 days (1870 hrs). Based on this half-life value, it 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. If released into the environment, 71.1% 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 17.33 days ( 416 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

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

                    

In a prediction done using the BCFBAF Program (v3.01) 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 22.95 L/kg whole body w.w (at 25 deg C).

 

In an another prediction done by using Bio-concentration Factor module, the Bio-concentration Factor over the entire pH scale (pH 1-14) of the test chemical was estimated to be 40.5, respectively.

 

In a supporting weight of evidence study from authoritative databases (2017) for the test item,bioaccumulation experiment was conducted for estimating the BCF (bioaccumulation factor) value of test chemical. The bioaccumulation factor (BCF) value was calculated using an estimated log Kow of 3.32 and a regression derived equation. The BCF (bioaccumulation factor) value test substance was determined to be 72 dimensionless.

 

For the test chemical,the bioaccumulation study was conducted in fish for estimating the BCF (bioaccumulation factor) value of test chemical (HSDB, 2017). The bioaccumulation factor (BCF) value was calculated using an estimated log Kow of 2.83 and a regression derived equation. The BCF (bioaccumulation factor) value test substance in fish was determined to be 34 dimensionless.

 

On the basis of above results for test chemical, it can be concluded that the BCF value of test chemical ranges was evaluated to be upto 72, 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. The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately measuring 4μL of test item and diluted with acetonitrile up to 10 ml. Thus, the test solution concentration was 396 mg/l. The pH of test substance was 6.5. 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 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,Ndimethylbenzamide, 3,5-dinitrobenzamide, N-methylbenzamide, Benzamide, phenanthrene, DDT, Acetanilide having Koc value ranging from 1.25 to 5.63. The Log Koc value of test chemical was determined to be 3.698 ± 0.000 at 25°C. This log Koc value indicates that the test chemical has a strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.