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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, the hydrolysis half-life value of the test chemical can be expected to be ranges from 2.1 to 3.3 yrs at pH 7.0 and 78 to 121 days at pH 8.0 with a corresponding hydrolysis rate constant of 0.063L/mol-sec & 0.10L/mol-sec, respectively. Thus, based on this half-life value, test chemical can be considered to be hydrolytically stable.

Biodegradation in water

Biodegradation study was conducted for 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 chemical and reference substance. 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 chemical and reference substance. 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 chemical 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 chemical, under the test conditions, was considered to be inherently biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface prediction model (2018) 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 prediction program (2018) 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 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, 2017). The solutions of the test substance and reference substances were prepared in appropriate solvents. A test chemical solution was prepared by accurately measuring 4μL of test chemical 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.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 its 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 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 read across chemical and applying the weight of evidence approach, the hydrolysis half-life value of the test chemical can be expected to be ranges from 2.1 to 3.3 yrs at pH 7.0 and 78 to 121 days at pH 8.0 with a corresponding hydrolysis rate constant of 0.063L/mol-sec & 0.10L/mol-sec, respectively. Thus, based on this half-life value, test chemical can be considered to be hydrolytically stable.

Biodegradation in water

Biodegradation study was conducted for 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 chemical and reference substance. 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 chemical and reference substance. 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 chemical 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 chemical, under the test conditions, was considered to be inherently biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface prediction model (2018) 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 inherently biodegradable in nature.

Bioaccumulation: aquatic / sediment

Various predicted data of the test chemical were reviewed for the bioaccumulation end point which are summarized as below:

 

In a prediction done using the BCFBAF Programof 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).

 

Using Bio-concentration Factor module(ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017)),bio-concentration factor over the entire pH scale (pH 1-14) of the test chemical was estimated to be 40.5.

 

Bioconcentration Factor (BCF) of test chemical was estimated using Chemspider database(2019). The bioconcentration factor of test chemical was estimated to be 68.55 at both pH 5.5 and 7.4, respectively.

 

Another predicted data was estimated using SciFinder database (American Chemical Society (ACS), 2019) for predicting the bioconcentration factor (BCF) of test chemical.The bioconcentration factor (BCF) of test chemical was estimated to be 44.3 at pH range 1-10 respectively (at 25 deg C).

 

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 28.0 dimensionless . The predicted BCF result based on the 5 OECD principles.

 

On the basis of above results for test chemical, it can be concluded that the BCF value of test substance was evaluated to be ranges from 22.95 to68.55, respectivelywhich does not exceed the bioconcentration threshold of 2000, indicating that the test chemical is not expected to bioaccumulate in the food chain.

Bioaccumulation endpoint can also be considered for waiver as per inaccordance 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, 2017). The solutions of the test substance and reference substances were prepared in appropriate solvents. A test chemical solution was prepared by accurately measuring 4μL of test chemical 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.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.

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