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Environmental fate & pathways

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Description of key information

Stability:

Hydrolysis:

Test chemical is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions.

Biodegradation:

Biodegradation in water:

28-days Closed Bottle test following the OECD guideline 301 D was performed to determine the ready biodegradability of the test chemical. 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 10E7 to 10E8 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 78.31 %. Degradation of Sodium Benzoate exceeds 13.25 % on 7 days & 61.44% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 0.85 mgO2/mg. ThOD was calculated as 2.47 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 34.41%. Based on the results, the test chemical, under the test conditions, was considered to be primary inherently biodegradable in nature.

Biodegradation in water and sediments:

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, 18.3% 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 0.854%), 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, 80.5% 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 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:

Bioaccumulation:aquatic /sediment:

The bioconcentration factor (BCF) for test chemical was determined according static fish test. The BCF value was observed to be 16-21 L/kg at dose concentration 0.0001 mg/L and 8.1-18 L/kg at dose concentration 0.00001 mg/L on test organism Cyprinus carpio during 6 weeks period. Therefore it is concluded that this test chemical is nonbioaccumulative.

Transport and distribution:

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 3.145 ± 0.031 at 25°C.This log Koc value indicates that the substance has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.

Additional information

Stability:

Hydrolysis:

Various studies have been reviewed to determine half life of hydrolysis of test chemical (from authoritative database). On the basis of all the studies it is concluded that test chemical does not undergo hydrolysis as it does not contain hydrolysable fuctional group therefore this chemical is considered to be stable.

Biodegradation:

Biodegradation in water:

Two experimental studies have been performed to determine biodegradability of test chemical in wtaer and results of all the studies are summarized below.

In first experimental study the 28-days Closed Bottle test following the OECD guideline 301 D was performed to determine the ready biodegradability of the test chemical. 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 10E7 to 10E8 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 78.31 %. Degradation of Sodium Benzoate exceeds 13.25 % on 7 days & 61.44% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD28 value of test chemical (was observed to be 0.85 mgO2/mg. ThOD was calculated as 2.47 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 34.41%. Based on the results, the test chemical, under the test conditions, was considered to be primary inherently biodegradable in nature.

Another study was reviewed from authoritative database in this study the biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability of test chemical. Activated sludge was used as a test inoculums for the study. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of test substance was determined to be 0 and 0.3 % by considering BOD and GC parameter in 14 days. Thus, based on percentage degradation, value test chemical is considered to be not readily biodegradable in nature.

By considering results of study report which is done according to OECD guideline 301 D it is concluded that test chemical is primary inherentlybiodegradable in nature.

Biodegradation in water and sediments:

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, 18.3% 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 0.854%), 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, 80.5% 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 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:

Bioaccumulation:aquatic /sediment:

Various experimental studies and one prediction study have been conducted to determine bioaccumulation concentartion factor (BCF) of test chemical and their results are summarized below

In first study the Bioaccumulation test was conducted for 6 weeks for determination the bioconcentration factor (BCF) of test chemical on test organism Cyprinus carpio.

 Recovery ratio : Test water : 1st concentration area : 90.1 %, 2nd concentration area : 79.6 %, Fish : 92.7 %, - Limit of detection : Fish : 0.

ppm And Nominal concentrations used in the study as - 1st Concentration area: 0.0001 mg/L, 2nd Concentration area : 0.00001 mg/L and Range finding study was carried out on Rice fish (Oryzias latipes) TLm(48h) 6.4 ppm(w/v), Rice fish (Oryzias latipes).

Thus according to static Fish test the bioconcentration factor (BCF) for test chemical was determined according static fish test. The BCF value was observed to be 16-21 L/kg at dose concentration 0.0001 mg/L and 8.1-18 L/kg at dose concentration 0.00001 mg/L on test organism Cyprinus carpio during 6 weeks period.

Therefore it is concluded that this test chemical is nonbioaccumulative.

Next study was also reviewed from authoritative database in this the BCF value of test chemical was estimated is 57 dimensionless by using log Kow of 3.50 and regression derived equation and it is far less than 2000 so it is concluded that this chemical is non bioaccumulative.

Last study was the prediction done from EPI suite (2018) in this the estimated bioconcentration factor (BCF) for test chemical iwas estimated to be 57.07L/kg wet-wt. This value does not exceed the bioconcentration threshold of 2000. Thus it is concluded that test chemical is not expected to bioaccumulate in the food chain.

On the basis of all the studies mentioned above it is concluded that the BCF value of test chemical is in range of 8.1 to 57 dimensionless. By considering this range BCF value it is concluded that test chemical is non- bioaccumulative in aquatic species.

Transport and distribution:

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 weighing 50mg of test item and diluted with mobile phase up to 100ml. Thus, the test solution concentration was 500mg/l. The pH of test substance was 7.52. 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 4-chloroaniline, 4-methylaniline, N methylaniline, 2-Nitrophenol, Nitrobenzene, 4-Nitrobenzamide, N,N-dimethylbenzamide, N-methylbenz amide, Benzamide, phenanthrene having Koc value ranging from 1.239 to 4.09. The Log Koc value of test chemical (1,1-Dimethylethyl)-4-methoxy phenol was determined to be 3.145 ± 0.031 at 25°C.

This log Koc value indicates that the substance has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.