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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 ranges from 38 days to 5.0 yrs, at pH range 7-8 and a temperature of 25°C.

Biodegradation in water

42-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test chemical (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 78.31%. Degradation of Sodium Benzoate exceeds 42.16% on 7 days & 63.25% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD42 value of test chemical was observed to be 1.22 mgO2/mg. ThOD was calculated as 2.70 mgO2/mg. Accordingly, the % degradation of the test item after 42 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 45.98%. 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 of biodegradation of test chemical in water and sediment done by EPI suite. Estimated half life of test chemical in water was 15 days (360 h) and in sediment estimated to be 135 days (3240 h).

Biodegradation in soil

Biodegradation in soil was predicted by EPI suite. Biodegradation half-life of test chemical in soil was estimated to be 30 days (720 hrs).

Bioaccumulation :

Based on the predicted data by BCFBAF Program (v3.01) model of EPI suite the Bioaccumulation factor (BCF) was predicted to be 14.52 L/kg wet-wt at 25°C.

Adsorption / desorption:

The Adsorption Coefficient of test chemical was determined as per the HPLC method (OECD Guideline-121). The Log Koc value was determined to be 2.739 ± 0.000 at 25°C.

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 base catalyzed second order hydrolysis rate constant and half-life value of test chemical was determined using a structure estimation method. The second order hydrolysis rate constant was determined to be 0.04 L/mol-sec with a corresponding half-life of 5 years and 200 days at pH 7 and 8, respectively. Based on the half-life values, it is concluded that the test chemical is not hydrolysable.

In an another study, 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.

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 ranges from 38 days to 5.0 yrs, at pH range 7-8 and a temperature of 25°C. Thus, based on this half-life value, it can be concluded that the test chemical is not hydrolysable in water.

Biodegradation in water

1: 42-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test chemical (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 78.31%. Degradation of Sodium Benzoate exceeds 42.16% on 7 days & 63.25% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD42 value of test chemical was observed to be 1.22 mgO2/mg. ThOD was calculated as 2.70 mgO2/mg. Accordingly, the % degradation of the test item after 42 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 45.98%. Based on the results, the test item, under the test conditions, was considered to be ultimate inherently biodegradable in nature.

WoE 2: Biodegradation study was conducted for 14 days to calculate the BOD, TOC and % degradation of test material during exposure period. Activated sludge of 30 mg/L conc was taken as inoculum and initial concentration of the test material was 100 mg/L. Test material analysis was done by GC. % degardation based on BOD was found to be 54.6. hence it can be concluded that the test item is not readily biodegradable.

WoE 3: Biodegradation study was conducted for 14 days to calculate the BOD, TOC and % degradation of test material during exposure period. Activated sludge of 30 mg/L conc was taken as inoculum and initial concentration of the test material was 100 mg/L. Test material analysis was done by GC. % degardation based on BOD was found to be 56. hence it can be concluded that the test item is not readily biodegradable.

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, 25.8% 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 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). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.245%), 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, 72.5% 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 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 :

Following different studies includes predicted study for the target chemical and experimental study for read-across analogues which is extracted by using mechanistic approach and functionally and structurally similar to the target chemical to observe the bioaccumulation of test chemical in water. The studies are as mentioned below:

Based on the predicted data by BCFBAF Program (v3.01) model the Bioaccumulation factor (BCF) was predicted to be 14.52 L/kg wet-wt at 25°C. Based on the BCF concentration it is concluded that the test chemical is non bioaccumulative in nature as it does not exceed the BCF criteria of 2000.

The second study 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 14.5 dimensionless . The predicted BCF result based on the 5 OECD principles. Thus based on the result it is concluded that the test substance is non-bioaccumulative in nature, because the bioconcentration factor in fish is less than 2000.

In next study, from Scifinder database the Bioconcentration factor (BCF) for target chemical was predicted to be 24.4 dimensionless at pH 1-10 and temperature 25 °C. Based on the BCF concentration it is concluded that the test chemical is non bioaccumulative in nature as it does not exceed the BCF criteria of 2000.

Another study using Bio-concentration Factor (v12.1.0.50374) moduler , bioconcentration of the chemical was estimated to be 295 dimensionless

at pH ranges from 1-14. This value indicates that the test chemical is non-bioaccumulative in aquatic organisms as this value does not exceed 2000 criteria.

In next study of read across chemical, bioaccumulation test was conducted for 8 weeks for determination the bioconcentration factor (BCF) of chemical on test organism Cyprinus carpio at different nominal concentrations of 0.2 mg/L (w/v) and 0.02 mg/L (w/v) and Range finding study was carried out on Rice fish (Oryzias latipes) at 48h which was determined to be 18 ppm(w/v).Thus The BCF value was observed to be 171-429 L/Kg at concentration of 0.2 mg/L and 187-345 L/Kg at 0.02 mg/L on test organism Cyprinus carpio during 8 weeks period. These BCF values indicate that the test substance is not bioaccumulative in aquatic organisms as these values are far less than 2000 criteria.

The last study is from authoritative database HSDB the BCF value of test chemical which was estimated to be 6 dimesionless by using an estimated log Kow of 1.36 and a regression derived equation. On the basis of this estimated BCF value it can be concluded that test chemical in non bioaccumulative in nature and the potential for bioconcentration in aquatic organisms is low.

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 A test item solution was prepared by accurately pipetting 4 microlitre of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 380 mg/l(calculated according to its density). The pH of test substance was 6.1. 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-naphthylamine, 1-naphthol, 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-methyl benzamide, Benzamide, phenanthrene, DDT having Koc value ranging from 1.25 to 5.63. The Log Koc value of test chemical was determined to be 2.739 ± 0.000 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.

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