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Environmental fate & pathways

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Description of key information

Hydrolysis

HYDROWIN v2.00 program of Estimation Programs Interface (EPI Suite, 2017) prediction model was used to predict the hydrolysis half-life of test compound

1-(3-aminophenyl)urea (CAS No. 25711 -72 -2). The estimated half-life of 1-(3-aminophenyl)urea was estimated to be > 1 year (at 25 deg C), indicating that it not hydrolysable.

Biodegradation in water

Biodegradability of 1-(3-aminophenyl)urea (CAS no. 25711 -72 -2) is predicted using OECD QSAR toolbox version 3.3 (2017) with logKow as the primary descriptor. Test substance undergoes 1% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 1-(3-aminophenyl)urea

was estimated to be not readily biodegradable in water.

Biodegradation in water and sediment

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound 1-(3-aminophenyl)urea (CAS No.25711 -72 -2). If released in to the environment, 30.1% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 1-(3-aminophenyl)urea 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 1 -(3 -aminophenyl)urea 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 0.0831%), indicates that 1 -(3 -aminophenyl)urea is not persistent in sediment.

Biodegradation in soil

The half-life period of 1-(3-aminophenyl)urea (CAS No. 25711 -72 -2) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 69.8% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 1-(3-aminophenyl)urea in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of 1-(3-aminophenyl)urea, 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 (EPI Suite, 2017) program was used to predict the bioconcentration factor (BCF) of test chemical 1-(3-aminophenyl)urea (CAS No. 25711 -72 -2). The bioconcentration factor (BCF) of 1-(3-aminophenyl)urea was estimated to be 3.162 L/kg whole body w.w (at 25 deg C) which does not exceed the bioconcentration threshold of 2000, indicating that the chemical 1-(3-aminophenyl)urea is not expected to bioaccumulate in the food chain.

Adsorption/desorption

KOCWIN model (v2.00) of Estimation Programs Interface (EPI Suite, 2017) was used to predict the soil adsorption coefficient i.e Koc value of test chemical

1-(3-aminophenyl)urea (CAS No. 25711 -72 -2). The soil adsorption coefficient i.e Koc value of 1-(3-aminophenyl)urea was estimated to be 17.87 L/kg (log Koc= 1.2521) by means of MCI method (at 25 deg C). This Koc value indicates that the substance 1-(3-aminophenyl)urea has a negligible sorption to soil and sediment and therefore have rapid migration to ground water.

Additional information

Hydrolysis

HYDROWIN v2.00 program of Estimation Programs Interface (EPI Suite, 2017) prediction model was used to predict the hydrolysis half-life of test compound

1-(3-aminophenyl)urea (CAS No. 25711 -72 -2). The estimated half-life of 1-(3-aminophenyl)urea was estimated to be > 1 year (at 25 deg C), indicating that it not hydrolysable.

Biodegradation in water

Various predicted data for the target compound 1-(3-aminophenyl)urea(CAS No. 25711-72-2) and various supporting weight of evidence studies for its closest read across substance with logKow as the primary descriptor were reviewed for the biodegradation end point which are summarized as below:

 

In a prediction done by SSS (2017) using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor, percentage biodegradability of test chemical1-(3-aminophenyl)urea(CAS No. 25711-72-2) was estimated.Test substance undergoes 1% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 1-(3-aminophenyl)urea was estimated to be not readily biodegradable in water.

 

In another prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound1-(3-aminophenyl)urea(CAS No. 25711-72-2) 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 chemical  1-(3-aminophenyl)urea is expected to be not readily biodegradable.

 

In a supporting weight of evidence study from authoritative database (J-CHECK, 2017) for the read across chemical 4-methylbenzene-1,3-diamine (CAS no. 95-80-7),biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability of read across substance 4 -methylbenzene-1,3 -diamine. 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 read across substance was determined to be 0, 3 and 7.9% by BOD, TOC removal and GC parameter in 14 days. Thus, based on percentage degradation, 4 -methylbenzene-1,3 -diamine is considered to be not readily biodegradable in nature.

 

For the same read across chemical 4-methylbenzene-1,3-diamine (CAS no. 95-80-7) from SRC PhysProp Database (2017), biodegradation study was conducted for 14 days for evaluating the percentage biodegradability of read across substance 4 -methylbenzene-1,3 -diamine. The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)) under aerobic conditions at a temperature of 25°C and a pH of 7.0, respectively. 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 read across substance was determined to be in the range of 0 -29% by BOD parameter in 14 days. Thus, based on percentage degradation, 4 -methylbenzene-1,3 -diamine is considered to be not readily biodegradable in nature.

 

In a supporting weight of evidence study for the read across chemical 2-amino-5-methylbenzene sulfonic acid (CAS no. 88-44-8),biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability of read across substance 2 -amino-5 -methylbenzene sulfonic acid (J-CHECK, 2017 and OECD SIDS, 2003). The study was performed according to OECD Guide-line 301 C "Ready Biodegradability: Modified MITI Test (I)" under aerobic conditions. Aniline was used as a reference substance 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. Reference substance undergoes >40% and >60% degradation in 7 and 14 days, respectively. The percentage degradation of read across substance was determined to be 0 and <0% degradation by BOD, O2 consumption, TOC removal, Test mat. analysis and UV-Vis parameter in 14 days. Thus, based on percentage degradation, 2 -amino-5 -methylbenzene sulfonic acid is considered to be not readily biodegradable in nature.

 

Another biodegradation study was conducted for evaluating the percentage biodegradability of read across substance 1,3-diaminobenzene (CAS no. 108-45-2) (George W. Malaney, 1960 and SRC PhysProp Database, 2017). Aniline-acclimated sludge was used as a test inoculum. The original source of microorganisms was mixed liquor from the aeration tank of a municipal treatment plant. Biodegradation of test chemical was tested by the conventional Warburg technique, using 125 ml flasks. Concentration of inoculum i.e, sludge used was 2,500 mg/l and initial test substance conc. used in the study was 500 mg/l. Incubation of the test vessel was carried out at 20ᵒC for 5-8 days i.e, 120-192 hrs. Oxidation in the test flask was recorded as mg O2 uptake per liter of the mixture in the flask. The mg of O2 uptake by the read across substance1,3-diaminobenzene was determined to be 210 mg/l and the percentage degradation of read across substance was determined to be 0% by BOD parameter in 8 days. Thus, based on percentage degradation,1,3 -diaminobenzene is considered to be not readily biodegradable in nature.

 

On the basis of above results for target chemical1-(3-aminophenyl)urea(from OECD QSAR toolbox version 3.3 and EPI suite, 2017) and for its read across substance (from authoritative database J-CHECK, SRC PhysProp Database, secondary source OECD SIDS and peer reviewed journal), it can be concluded that the test substance1-(3-aminophenyl)ureacan be expected to be not readily biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound 1-(3-aminophenyl)urea (CAS No.25711 -72 -2). If released in to the environment, 30.1% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 1-(3-aminophenyl)urea 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 1 -(3 -aminophenyl)urea 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 0.0831%), indicates that 1 -(3 -aminophenyl)urea is not persistent in sediment.

Biodegradation in soil

The half-life period of 1-(3-aminophenyl)urea (CAS No. 25711 -72 -2) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 69.8% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 1-(3-aminophenyl)urea in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of 1-(3-aminophenyl)urea, 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 substance 1 -(3 -aminophenyl)urea can be considered to be not readily biodegradable in nature.

Bioaccumulation: aquatic/sediment

Various predicted data for the target compound 1-(3-aminophenyl)urea (CAS No. 25711-72-2) were reviewed for the bioaccumulation end point which are summarized as below:

 

In a prediction done using the BCFBAF Program (v3.01) of Estimation Programs Interface (EPI Suite, 2017), the bioconcentration factor (BCF) of test chemical 1-(3-aminophenyl)urea (CAS No. 25711 -72 -2) was estimated to be 3.162 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 (ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017), the BCF over the entire pH scale (pH 0 - 14) of the test substance 1-(3-aminophenyl)urea (CAS no. 25711 -72 -2) was estimated to be 1.

 

Bioaccumulation test was conducted for estimating the bioconcentration factor (BCF) of test chemical 1-(3-aminophenyl)urea (CAS no. 25711 -72 -2) (ChemSpider, 2017). The bioconcentration factor (BCF) of 1-(3-aminophenyl)urea was estimated to be 1.00 at pH 5.5 and 7.4, respectively.

 

Another prediction was done using SciFinder database (American Chemical Society (ACS), 2017) for the bioconcentration factor (BCF) of test chemical 1-(3-aminophenyl) urea (CAS No. 25711 -72 -2). The bioconcentration factor (BCF) of 1-(3-aminophenyl)urea was estimated to be 1 (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 substance 1-(3-aminophenyl)urea was estimated to be 1.71 dimensionless . The predicted BCF result based on the 5 OECD principles. Thus based on the result it is concluded that the test substance 1-(3-aminophenyl)urea is non-bioaccumulative in nature.

 

On the basis of above results for target chemical1-(3-aminophenyl)urea(from EPI suite, ACD labs,ChemSpider, SciFinder database and CompTox Chemistry Dashboard,  2017), it can be concluded that the BCF value of test substance1-(3-aminophenyl)urea ranges from 1 – 3.162 which does not exceed the bioconcentration threshold of 2000, indicating that the chemical 1-(3-aminophenyl)urea is not expected to bioaccumulate in the food chain.

Adsorption/desorption

Various predicted data for the target compound 1-(3-aminophenyl)urea(CAS No. 25711-72-2) were reviewed for the adsorption end point which are summarized as below:

 

Using the KOCWIN Program (v2.00) of Estimation Programs Interface (EPI Suite, 2017) the soil adsorption coefficient i.e Koc value of test chemical 1-(3-aminophenyl)urea (CAS No. 25711 -72 -2) was predicted. The soil adsorption coefficient i.e Koc value of 1-(3-aminophenyl)urea was estimated to be 17.87 L/kg (log Koc= 1.2521) by means of MCI method (at 25 deg C).

 

The Soil Adsorption Coefficient i.e Koc value of test substance 1-(3-aminophenyl)urea was estimated using Adsorption Coefficient module (v12.1.0.50374) program at pH 0-3, 4, 5, 6, 7-10, 11, 12, 13 and 14 as Koc approx. 1, 3.96, 12.3, 15.6, 16.1, 16.0, 15.0, 9.19 and 2.00, respectively (Log Koc ranges from 0.3 ± 1.0 to 1.2 ± 1.0) (ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017).

 

In an another prediction done by using ChemSpider Database (2017), the Soil Adsorption Coefficient i.e Koc value of test substance 1-(3-aminophenyl)urea (CAS no. 25711 -72 -2) was estimated to be 20.76 (log Koc = 1.317) and 22.76 (log Koc = 1.357) at pH 5.5 and 7.4, respectively.

 

Additional soil adsorption coefficient i.e Koc value of test chemical 1 -(3 -aminophenyl)urea (CAS No. 25711 -72 -2) was estimated using the SciFinder database (American Chemical Society (ACS), 2017). The soil adsorption coefficient i.e Koc value of 1 -(3 -aminophenyl)urea was estimated to be 1.0, 4.55, 14.1, 17.9, 18.4 and 18.5 at pH 1 -3, 4, 5, 6, 7 and 8 -10 (at 25 deg C), respectively.

 

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 substance 1 -(3 -aminophenyl) urea was estimated to be 31.9 L/kg (log Koc = 1.503) .The predicted KOC result based on the 5 OECD principles. Thus based on the result it is concluded that the test substance 1-(3-aminophenyl)urea is mobile in soil.

 

On the basis of above results for target chemical 1-(3-aminophenyl)urea (from EPI suite, ACD labs,ChemSpider, SciFinder database and CompTox Chemistry Dashboard,2017), it can be concluded that the Koc value of test substance 1-(3-aminophenyl)urea ranges from 1 – 31.9 indicating that the test chemical has a negligible sorption to soil and sediment and therefore have a rapid migration potential to groundwater.