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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 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 > 1 yr, at pH range 4, 7 & 9 and a temperature of 50°C, respectively. Thus, based on this half-life value, 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, 14.1% 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 0.185%), 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, 85.7% 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

In accordance with column 2 of Annex IX of the REACH regulation,testing for this endpointis scientifically not necessary and does not need to be conducted since the test chemical has a low potential for bioaccumulation based on logKow ≤ 3.

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 5 ml water and make with Acetonitrile up to 10ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 6.6. 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 Acetanilide, 4-chloroaniline, 4-methylaniline(p-Tolouidine), N-methylaniline, ptoluamide, Aniline, 2,5 -Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4-Nitrobenzamide, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, Pentachlorophenol, Benzamide, phenanthrene having Koc value ranging from 1.25 to 4.09. The Log Koc value of test chemical was determined to be 0.635± 0.000 at 25°C. This log Koc value indicates that the test chemical has a negligible sorption to soil and sediment and therefore have rapid 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 50°C.Test substance was added in the test water of pH 4, pH 7 and pH 9 to be the test concentration of about 0.05 mg/L. These test solutions were shaked for 5 days at 50 degree C. After that, the test chemical concentration of each test water was measured and compared with the initial concentration. Analytical method involve the use of HPLC. L-column ODS (15 cm x 4.6 mm I.D.) was used as a column for the study. Although the half-life value of test chemical was not known, but the residues of the test chemical were more than 90 % in all the pH. Thus, the test chemical was reported to be stable in water at a temperature of 50⁰C and at pH 4, 7 and 9, respectively. Based on the half-life values, it is concluded that the test chemical is not hydrolysable.

 

For the test chemical, the half-life of the test chemical was determined. The study was performed at a temperature of 50⁰C. Test chemical was reported to be hydrolytically stable with a corresponding half-life value of> 1 yrat a temperature of 50⁰C, respectively. Thus, based on the half-life value, it is concluded that the test chemical is not hydrolysable in water.

 

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 > 1 yr, at pH range 4, 7 & 9 and a temperature of 50°C, respectively. Thus, based on this half-life value, it can be concluded that the test chemical is not hydrolysable in water.

Biodegradation in water

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

 

In a prediction done using Estimation Programs Interface Suite (2018), the biodegradation potential of the test chemical in the presence of mixed populations of environmental microorganisms was predicted. 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 study from peer reviewed journal (Elias Razo Flores et. al., 1996) for the test item,biodegradation experiment was conducted for 150 days for evaluating the percentage biodegradability of test chemical. The study was performed under anaerobic conditions at a temperature of 30°C.The methanogenic granular sludge obtained from a full-scale upward-flow anaerobic sludge bed reactor (UASB) treating a petrochemical wastewater containing benzoate and acetate as primary substrates was used as a test inoculum for the study .The sludge was elutriated to remove the fines and predigested at 30°C during a 30 days period in order to deplete all endogenous substrate in the sludge. The sludge contained 10.5% TSS and 8.5% VSS. Initial test substance conc. used in the study was 100 mg/l, respectively. 120 ml glass serum flask was used as a test vessel for the study. Basal medium was used as a test medium for the study, with the exception of NaHCO3 supplied at 5 g/l. Predigested granular sludge (1 g VSS/L) was transferred to serum flasks containing 24 mL of the basal medium and acetate from a neutralized stock to yield a final concentration of 50 mg of chemical oxygen demand (COD)/L. The serum flasks were sealed with 12 mm thick butyl rubber stoppers and flushed with 70% N2-30% CO2 gas for 5 minutes and incubated overnight at 30°C to allow for biological consumption of residual O2. The desired amount of test chemical was then added to triplicate serum flasks using concentrated stock solutions. Later serum flasks were incubated with shaking (50 rpm) in a temperature controlled room at 30°C over a 150 day period. The methane composition in the headspace of each serum flask was monitored periodically during the assays. The serum flasks were shaken vigorously before gas measurements were taken. Methane production was calculated from the volume of the headspace and the methane composition in the gas. Net methane production was calculated by subtracting background methane production in the controls from that in the test vials. The corrected methane production (M) was expressed as a percentage of the theoretical methane production (TMP) expected from the test chemical mineralization. Sludge blank which contains no test chemical was setup to correct for background gas production from the sludge. Both Benzoate and phenol were used as reference compounds in the study. The concentrations of benzoate and phenol used were 250 mg/L. The benzoate was completely degraded in 20 days and the phenol in 45 days. ultimate conversion of the substrate COD to methane was equal to 85.5% ± 1.82 and 82.8% ± 2.32 for benzoate and phenol respectively. The percentage degradation of test chemical was determined to be 0% after 150 days. Thus, based on percentage degradation, test chemical is considered to be not biodegradable in water.

 

Another biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test chemical (from authoritative database, 2018 and secondary source, 2014). The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I) under aerobic conditions. Activated sludge was used as 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 chemical was determined to 0 and 5% by BOD, TOC removal and HPLC parameter in 28 days. Thus, based on percentage degradation, test chemical is considered to be not readily biodegradable in nature.

 

For the test chemical, biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of test chemical (from authoritative database, 2018 and secondary source, 2010). The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I) under aerobic conditions. 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 chemical was determined to be 23 and 0% by BOD, TOC removal and HPLC parameter in 28 days. Thus, based on percentage degradation, test chemical is considered to be not readily biodegradable in nature.

 

On the basis of above overall results of test chemical, it can be concluded that the test chemical can be considered 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, 14.1% 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 0.185%), 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, 85.7% 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 biodegradable in nature.

Bioaccumulation: aquatic / sediment

In accordance with column 2 of Annex IX of the REACH regulation,testing for this endpointis scientifically not necessary and does not need to be conducted since the test chemical has a low potential for bioaccumulation based on logKow ≤ 3.

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 5 ml water and make with Acetonitrile up to 10ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 6.6. 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 Acetanilide, 4-chloroaniline, 4-methylaniline(p-Tolouidine), N-methylaniline, ptoluamide, Aniline, 2,5 -Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4-Nitrobenzamide, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, Pentachlorophenol, Benzamide, phenanthrene having Koc value ranging from 1.25 to 4.09. The Log Koc value of test chemical was determined to be 0.635± 0.000 at 25°C. This log Koc value indicates that the test chemical has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.