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Environmental fate & pathways

Endpoint summary

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Description of key information

Hydrolysis:

On the basis of the experimental studies of the test chemical and applying the weight of evidence approach, the hydrolysis half-life value of the test chemical can be expected to be ranges from > 20 days to 1.4 yr, at pH range 7-8 & temperature of 20.1-20.5⁰C, respectively. Thus, based on this half-life value, it can be concluded that the test chemical is not hydrolysable in water.

Biodegradation in water:

The test item  undergoes 46.92 % biodegradation after 42 days in the test condition. Thus, the test item was considered to be ultimate inherently biodegradable.

Bioaccumulation :

Based on the predicted data by BCFBAF Program (v3.01) model the Bioaccumulation factor (BCF) was predicted to be 61.87 L/kg wet-wt at 25 deg.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.

Adsorption/desorption:

The Adsorption Coefficient of test substance  was determined as per the HPLC method (OECD Guideline-121). The Log Koc value was determined to be 2.474 ± 0.0008 at 25°C. Thus based on the result it is concluded that the test substance  has moderate sorption to soils and sediment, slow migration potential to ground water

Additional information

Hydrolysis:

Data available for the test chemical has been reviewed to determine the half-life of hydrolysis as a function of pH. The studies are as mentioned below:

 

The half-life of the test chemical was determined at different pH range. The study was performed at a pH range7.4 to 7.8 and a temperature of 20.1 to 20.5⁰C, respectively. The test substance was dissolved in dechlorinated tap water. The concentration of the test substance was measured in the supernatant of the test solution centrifuged. The test substance was measured on day 0, 1, 3, 6, 8, 10, 13, 15, 17, and 20 over a 21-day period. The test concentration used was considered to be at saturation in water. Based on the measured concentration of test chemical in water, chemical was reported to be hydrolytically stable at pH range7.4 to 7.8 and a temperature of 20.1 to 20.5⁰C for 20 days. Test chemical appears to be in equilibrium and does not appear to be breaking down in water. The concentration of test chemical is not decreasing with time. Thus, the half-life value of test chemical was determined to be > 20 days and on the basis of this, test chemical is considered to be 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 chemical was determined to be 0.16L/mol-sec with a corresponding half-lives of 1.4 yrs and 51 days at pH 7 and 8, 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 test chemical and applying the weight of evidence approach, the hydrolysis half-life value of the test chemical can be expected to be ranges from > 20 days to 1.4 yr, at pH range 7-8 & temperature of 20.1-20.5⁰C, respectively. Thus, based on this half-life value, it can be concluded that the test chemical is not hydrolysable in water.

Biodegradation in water:

42-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test item. The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used as inoculum at concentration 10E7 to 10E8 CFU/ml. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32ml/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 72.28 %. Degradation of Sodium Benzoate exceeds 45.18 % on 7 days & 59.03% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD42 value of test substance was observed to be 1.07 mgO2/mg. ThOD was determined by calculation as 2.28 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 46.92 %. Based on the results, the test item under the test conditions was considered to be ultimate inherently biodegradable in nature.

 

Bioaccumulation :

Following different studies includes estimated study for the target chemical to observe the bioaccumulation of test chemical in water.

Based on the predicted data by BCFBAF Program (v3.01) model the Bioaccumulation factor (BCF) was predicted to be 61.87 L/kg wet-wt at 25 deg.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.

Based on the predicted data from PBT profiler the Bioaccumulation factor (BCF) was predicted to be 62 L/kg wet-wt at 25°C. On the basis of BCF concentration it is concluded that the test chemical is non bioaccumulative in nature as it does not exceed the BCF criteria of 2000.

From Scifinder database the Bioconcentration factor (BCF) for target chemical was predicted to be 1.53 at pH 1,8.14 at pH 2,58.7 at pH3, 185 at pH 4, 237 at pH 5, 244 at pH 6-10 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.

From Chemspider - ACD/PhysChem Suite prediction model the Bioconcentration factor (BCF) for target chemical was predicted to be 201.24 at pH 5.5 and  203.25 at 7.4 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.

On the basis of BCF concentration it is concluded that the test chemical is non bioaccumulative in nature as it does not exceed the BCF criteria of 2000.

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 6 mg of test item and diluted with acetonitrile up to 10 ml. Thus, the stock solution concentration was 600 mg/l. This was further diluted by taking 1mL stock solution and making up the volume up to 10mL with acetonitrile. Thus, the final test solution concentration was 60 mg/L. The pH of test substance was 6.86. 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 aniline, 4-methylaniline, N-methylaniline, toluene, xylene, ethylbenzene and naphthalene were chosen having Koc value range from 1.9 to 2.75. The Log Koc value of test material was determined to be 2.474 ± 0.0008 dimensionless at 25°C.This log Koc value indicates that the substance has Moderate sorption to soils and sediment, slow migration potential to ground water.