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Environmental fate & pathways

Endpoint summary

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Description of key information

Hydrolysis

HYDROWIN v2.00 program of Estimation Programs Interface prediction model was used to predict the hydrolysis half-life of test chemical. The estimated half-life of test chemical was determined to be 3950 yrs at pH 7.0 (at 25ᵒC) respectively, indicating that it is stable in water.

Biodegradation in water

Estimation Programs Interface Suite 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, 6.63% 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 60 days (1440 hrs). The half-life (60 days estimated by EPI suite) indicates that the chemical is persistent in water and the exposure risk to aquatic animals is moderate to high whereas the half-life period of test chemical in sediment is estimated to be 541.66 days (13000 hrs). Based on this half-life value, it indicates that test chemical is 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, 78.1% 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 120 days (2880 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 was used to predict the bioconcentration factor (BCF) of test chemical. The bioconcentration factor (BCF) of test chemical was estimated to be 176.1 L/kg whole body w.w (at 25 deg C) which does not exceed the bio concentration threshold of 2000, indicating that the test chemical is not expected to bioaccumulate in the food chain.

Adsorption / desorption

KOCWIN model (v2.00) of Estimation Programs Interface was used to predict the soil adsorption coefficient i.e Koc value of test chemical.The soil adsorption coefficient i.e Koc value of test chemical was estimated to be 30460 L/kg (log Koc=4.4837) by means of MCI method (at 25 deg C). This Koc value indicates that the test chemical has a very strong sorption to soil and sediment and therefore have negligible migration potential to ground water.

Henry's law constant

Henry's Law constant of test chemical was estimated to be 0.00000000000000942 (9.42E-015) Pa-m3/mole at 25 deg.C

Additional information

Hydrolysis

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

 

In a prediction done using the HYDROWIN v2.00 program of Estimation Programs Interface (Modelling database, 2011) prediction model was used to predict the hydrolysis half-life of test chemical. The estimated half-life of test chemical was determined to be 3950 yrs at pH 7.0 (at 25ᵒC) respectively, indicating that it is stable in water

 

In a supporting weight of evidence study from handbook (2008) and secondary source, 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 half-life value of test chemical was mentioned, but was reported to be stable at a pH 4, 7 and 9 at 25⁰C temperature. This indicates that the test chemical is hydrolytically stable.

 

For the test chemical, the half-life of the test chemical was determined (secondary source, 2001). The study was performed according to OECD Guideline 111 (Hydrolysis as a Function of pH). Percentage degradation of test chemical was determined to be 3.91%, 1.085% and 4.78% at pH 4.0, 7.0 and 9.0 & at a temperature of 50°C, respectively and the half-life value of test chemical was determined to be > 1 yr. Since the chemical is not degradable less than 10 % in this test condition, it is presumably stable in water. Thus based on this, test chemical is considered to be hydrolytically stable.

 

On the basis of the above results of the test chemical, it can be concluded that the test chemical is stable in water.

Biodegradation in water

Predicted data for the test chemical and various supporting weight of evidence studies for its structurally and functionally 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 (2017), the biodegradation potential of the test chemical in 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 peer reviewed journal (U. Pagga, et. al., 1986) for the test chemical,the aerobic biodegradation experiment was performed for test chemical using activated sludge at concentration 0.5 g/L dry material as inoculums and initial concentration of chemical taken was 100mg/L for 42 days. By considering DOC removal parameter test chemical showed 29 % degradation in 42 days. The test chemical belongs to B category according to table 1 and 2 as its limit value falls in that range. On the basis percentage value it is concluded that test chemical is not readily biodegradable.

 

Another biodegradation study was conducted for 5 days for evaluating the percentage biodegradability of test chemical using 5 day BOD test under aerobic conditions (authoritative database HSDB, 2017). Sewage sludge was used as a test inoculum. Initial test substance conc. used in the study was 2.5 mg/l. The percentage degradation of test substance was determined to be 0% by BOD parameter in 5 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 28 days for evaluating the percentage biodegradability of test substance (authoritative database J-CHECK and EnviChem, 2017). The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I). 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 1 and 3% by BOD and HPLC parameter in 28 days. Thus, based on percentage degradation, test chemical is considered to be not readily biodegradable in nature.

 

In an additional study from authoritative databases (2017), biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability of test substance. The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)) under aerobic conditions. 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 0.2 and 0.3% 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 of 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, 6.63% 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 60 days (1440 hrs). The half-life (60 days estimated by EPI suite) indicates that the chemical is persistent in water and the exposure risk to aquatic animals is moderate to high whereas the half-life period of test chemical in sediment is estimated to be 541.66 days (13000 hrs). Based on this half-life value, it indicates that test chemical is 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, 78.1% 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 120 days (2880 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

Various predicted data of the test chemical and supporting weight of evidence studies for its structurally and functionally similar read across substance were reviewed for the bioaccumulation end point which are summarized as below:

 

In aprediction done using theBCFBAF Program(v3.01) of 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 176.1 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 over the entire pH scale of the test chemical was estimated to be 4.57, 31.3, 186, 387, 434, 438, 430, 360, 137, 19.4, 2.30 and 1.0 at pH 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 & 11-14, respectively.

 

Bioconcentration Factor (BCF) of test chemical was estimated using Chemspider database. The bioconcentration factor of test chemical was estimated to be 1068.6 at pH 5.5 and 693.19 at pH 7.4, respectively.

 

Another predicted data was estimated usingSciFinder database (American Chemical Society (ACS), 2017) was used for predicting the bioconcentration factor (BCF) of test chemical. The bioconcentration factor (BCF) of test chemical was estimated to be 44.6, 266, 552, 618, 625, 613, 514, 196, 27.6 and 3.27 at pH range 1, 2, 3, 4, 5, 6, 7, 8, 9 and 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 19 dimensionless . The predicted BCF result based on the 5 OECD principles.

 

In supporting weight of evidence study from authoritative database (2017) for the test item,the BCF value of test chemical estimated was 500 dimensionless by using log Kow of 8.69 and regression derived equation and it is less than 2000 criteria therefore it is concluded that test chemical is non-bioaccumulative in aquatic organisms.

 

For the test chemical (authoritative database, 2017),the BCF value of test chemical estimated was 260 dimensionless by using log Kow of 4.0 and regression derived equation and it is less than 2000 criteria therefore it is concluded that test chemical is non bioaccumulative.

 

On the basis of above results of the test chemical, it can be concluded that the BCF value of test chemical ranges from 1 –1068.6 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

Various predicted data of the test chemical and supporting weight of evidence study for its structurally and functionally similar read across substance were reviewed for the adsorption end point which are summarized as below:

 

In aprediction done using theKOCWIN Program(v2.00) of Estimation Programs Interface was used to predict the soil adsorption coefficient i.e Koc value of test chemical. The soil adsorption coefficient i.e Koc value of test chemical was estimated to be 30460 L/kg (log Koc=4.4837) by means of MCI method (at 25 deg C). This Koc value indicates that the test chemical has a very strong sorption to soil and sediment and therefore have negligible migration potential to ground water.

 

In an another prediction done by using ChemSpider Database (2017), theSoil Adsorption Coefficient i.e Koc value of test chemical was estimated. The adsorption coefficient (Koc) value of test chemical was estimated to be 5113 (Log Koc = 3.7086) at pH 5.5 and 3317 (Log Koc = 3.52) at pH 7.4, respectively. This 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 soil adsorption coefficient i.e Koc value of test chemical was estimated using the SciFinder database (2017).The soil adsorption coefficient i.e Koc value of test chemical was estimated to be 249, 1480, 3080, 3450, 3490, 3420, 2870, 1090, 154 and 18.3 at pH range 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, respectively (at 25 deg C) (logKoc ranges from 1.26 to 3.5428). The logKoc value (3.4578 at pH 7.0) indicates that the test chemical has a strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.

 

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 adsorption coefficient i.e KOC for test chemical was estimated to be 5170 L/kg (log Koc = 3.713).The predicted KOC result based on the 5 OECD principles. This 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.

 

In a supporting weight of evidence study from authoritative database (2017) for the test item,adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical. The adsorption coefficient (Koc) value was calculated using a structure estimation method based on molecular connectivity indices. The adsorption coefficient (Koc) value of test substance was estimated to be 4800000 (Log Koc = 6.681). This Koc value indicates that the test substance has a very strong sorption to soil and sediment and therefore have negligible migration potential to ground water.

 

For the test chemical, adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical (HSDB and PubChem, 2017). The adsorption coefficient (Koc) value was calculated using a structure estimation method based on molecular connectivity indices. The adsorption coefficient (Koc) value of test chemical was estimated to be 4000 (Log Koc = 3.602). This 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.

 

On the basis of above overall results of the test chemical, it can be concluded that the logKoc value of test chemical was estimated to be ranges from 3.4578 to 4.4837 (at pH 7.0) indicating that the test chemicalhas a strong to very strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.

Henry's law constant

Henry's Law constant of test chemical was estimated to be 0.00000000000000942 (9.42E-015) Pa-m3/mole at 25 deg.C