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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 the test chemical can be expected to undergoe > 5 days to 1.4 yrs at a pH range 4-9, respectively & at a temperature of 25⁰C. Thus, based on this, it can be concluded that the test chemical is not hydrolysable in water.

Biodegradation in water

Estimation Programs Interface Suite (2018) was run to predict the biodegradation potential of the test chemical in the presence of mixed populations of environmental microorganisms. The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI LInear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that test chemical is expected to be 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, 10.6% 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 5% (i.e, reported as 4.92%), 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, 84.5% 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: aquatic / sediment

BCFBAF model (v3.01) of Estimation Programs Interface (2018) prediction program was used to predict the bioconcentration factor (BCF) of test chemical. The bioconcentration factor (BCF) of test chemical was estimated to be 44.63 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, 2018). The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with ACN up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 6.2. 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(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 Functional similarity with the test substance and calibration graph prepared. The reference substances were Xylene, Ethylbenzene, Toluene, Naphthalene, phenanthrene having Koc value ranging from 2.369 to 4.09. The Log Koc value of test chemical was determined to be 3.152 ± 0.000 dimensionless 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

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 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 25°C and pH 4, 7 and 9, respectively. Although the exact half-life value of test chemical was not known, but was reported to be stable during a period of 5 days. Thus, the half-life value of test chemical can be determined to be > 5 days at a pH 4, 7 and 9 & at a temperature of25⁰C, respectively, indicating that the test chemical is 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 structurally and functionally similar read across chemical and applying the weight of evidence approach, the hydrolysis the test chemical can be expected to undergoe > 5 days to 1.4 yrs at a pH range 4-9, respectively & at a temperature of 25⁰C. Thus, based on this, it can be concluded that the test chemical is not hydrolysable in water.

Biodegradation in water

Predicted data for the test chemical and various supporting weight of evidence studies for its structurally similar read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In a prediction using the Estimation Programs Interface Suite (2018), the biodegradation potential of the test chemicalin the presence of mixed populations of environmental microorganisms was estimated. The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that test chemical is expected to be not readily biodegradable.

 

In a supporting weight of evidence study from authoritative database (HSDB, 2017), biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability of test chemical under aerobic conditions. Initial test substance conc. used for the study was 100 mg/l. The percentage degradation of test chemical was determined to be in the range of 0 -5% by using BOD parameter in 14 days. Thus, based on percentage degradation, test chemical is considered to be not readily biodegradable in nature.

 

Another biodegradation study was conducted for 14 days for evaluating the percentage biodegradability of test chemical (authoritative database, 2017). 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 chemical was determined to be 5% by GC parameter in 14 days. Thus, based on percentage degradation, test chemical is considered to be not readily biodegradable in nature.

 

For the test chemical, biodegradation study was conducted for 14 days for evaluating the percentage biodegradability of test chemical (J-CHECK, 2017 and Envichem, 2014). Concentration of inoculum i.e, sludge used was 100 mg/l and initial test substance conc. used in the study was 30 mg/l, respectively. The percentage degradation of test chemical was determined to be 0% by BOD and GC parameter in 14 days. Thus, based on percentage degradation, test chemical is considered to be not readily biodegradable in nature.

 

On the basis of above results for test chemical, it can be concluded that the test chemical can be expected to be not readily biodegradable in nature.

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, 10.6% 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 5% (i.e, reported as 4.92%), 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, 84.5% 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.

On the basis of available information, the test chemical can be considered to be not readily biodegradablein 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 theBCFBAF Program (v3.01) of Estimation Programs Interface (2018), the bioconcentration factor (BCF) of test chemical was estimated. The estimated bioconcentration factor (BCF) of test chemical was estimated to be 44.63 L/kg whole body w.w (at 25 deg C).

In an another prediction done by using Bio-concentration Factor (v12.1.0.50374) module Bio-concentration Factor (ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017) over the entire pH scale (pH 0 - 14) of the test chemical was estimated to be 492 (log BCF = 2.7 ± 1.0).

 

Bioaccumulation test was conducted for estimating the bioconcentration factor (BCF) of test chemical (ChemSpider, 2017). The estimated bioconcentration factor (BCF) of test chemical was estimated to be 433.29 at pH 5.5 and 7.4, respectively.

 

Another predicted data was estimated using SciFinder database (American Chemical Society (ACS), 2017) in which the bioconcentration factor (BCF) of test chemical was predicted. The estimated bioconcentration factor (BCF) of test chemical was estimated to be 467 (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 5.05 dimensionless . The predicted BCF result based on the 5 OECD principles.

 

On the basis of above results for test chemical(from modelling databases,2017), it can be concluded that the BCF value of test chemicalranges from 5.05 – 492 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, 2018). The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with ACN up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 6.2. 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(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 Functional similarity with the test substance and calibration graph prepared. The reference substances were Xylene, Ethylbenzene, Toluene, Naphthalene, phenanthrene having Koc value ranging from 2.369 to 4.09. The Log Koc value of test chemical was determined to be 3.152 ± 0.000 dimensionless 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.