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Environmental fate & pathways

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Description of key information

Hydrolysis

On the basis of the experimental studies of the read across chemical and applying the weight of evidence approach, test chemical was reported to be hydrolytically stable at pH 4, 7 and 9, respectively and at a temperature of 50⁰C. Considering this result and as per the OECD TG 111 (Annnex 1), half-life of test chemical would be expected to be > 1 year at 25°C. Thus, test chemical was considered to be stable in water.

Biodegradation in water

Biodegradation study was conducted for 42-days in accordance with 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 chemical and reference substance. Polyseed were used as a test inoculum for the study. The concentration of test and reference chemical (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 chemical) was also calculated using BOD & ThOD and was determined to be 66.26%. Degradation of Sodium Benzoate exceeds 70.48% on 7 days & 73.49% on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD42 value of test chemical was observed to be 0.4 mgO2/mg. ThOD was calculated as 1.02 mgO2/mg. Accordingly, the % degradation of the test chemical after 42 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 39.21%. Based on the results, the test chemical, under the test conditions, was considered to be inherently biodegradable in nature.

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 chemical solution was prepared by accurately weighing 4 mg of test chemical and diluted with 5 ml water and make with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 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. 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-naphtol, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, Pentachlorophenol, N,N-dimethylbenzamide, 3,5 -dinitrobenzamide, Benzamide, phenanthrene having Koc value ranging from 1.25 to 4.09. The Log Koc value of test chemical was determined to be 1.303±0.000 dimensionless at 25°C.This log Koc value indicates that the substance has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.

Additional information

Hydrolysis

Data available of the read across chemicals has been reviewed to determine the hydrolysis half-life value of the test chemical. The studies are as mentioned below:

 

The half-life of the test chemical was determined. Test chemical does not contain the functional group that hydrolyze in water. For hydrolysis to occur, the only reactivity in water involves desulfonation of the aromatic sulfonic acid or its corresponding sulfonic acid salt. In aqueous acid (sulfuric acid), aromatic sulfonic acids desulfonate at temperatures of 100 to 175 deg C. Although these conditions would not be typically encountered in the environment, it was reported that the test chemical is stable in water.

 

For the test chemical, the half-life of the test chemical was determined at different pH range. The study was performed according to OECD Guideline 111 (Hydrolysis as a Function of pH) at a temperature of 50°C. Although, half-life value of test chemical is not known, but chemical was reported to be hydrolytically stable at pH 4, 7 and 9, respectively and at a temperature of 50⁰C. Considering this result and as per the OECD TG 111 (Annnex 1), half-life of test chemical would be expected to be > 1 year at 25°C.

 

On the basis of the experimental studies of the read across chemical and applying the weight of evidence approach, test chemical was reported to be hydrolytically stable at pH 4, 7 and 9, respectively and at a temperature of 50⁰C. Considering this result and as per the OECD TG 111 (Annnex 1), half-life of test chemical would be expected to be > 1 year at 25°C. Thus, test chemical was considered to be stable in water.

Biodegradation in water

Biodegradation study was conducted for 42-days in accordance with 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 chemical and reference substance. Polyseed were used as a test inoculum for the study. The concentration of test and reference chemical (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 chemical) was also calculated using BOD & ThOD and was determined to be 66.26%. Degradation of Sodium Benzoate exceeds 70.48% on 7 days & 73.49% on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD42 value of test chemical was observed to be 0.4 mgO2/mg. ThOD was calculated as 1.02 mgO2/mg. Accordingly, the % degradation of the test chemical after 42 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 39.21%. Based on the results, the test chemical, under the test conditions, was considered to be inherently biodegradable in nature.

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 chemical solution was prepared by accurately weighing 4 mg of test chemical and diluted with 5 ml water and make with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 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. 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-naphtol, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, Pentachlorophenol, N,N-dimethylbenzamide, 3,5 -dinitrobenzamide, Benzamide, phenanthrene having Koc value ranging from 1.25 to 4.09. The Log Koc value of test chemical was determined to be 1.303±0.000 dimensionless at 25°C.This log Koc value indicates that the substance has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.