4'-aminoazobenzene-4-sulphonic acid

Endpoint summary

Description of key information

Stability:

Biodegradation:

Biodegradation in water

Estimation Programs Interface Suite (EPI suite, 2018) was run to predict the biodegradation potential of the test compound 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 the test chemical is expected to be not readily biodegradable.

 

Biodegradation in water and sediment

Estimation Programs Interface (EPI Suite, 2018) prediction model was run to predict the half-life in water and sediment for the test compound. The Test chemical If released in to the environment, 16.2% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of the 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 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 sediment is less than 1 %( i.e., reported as 0.129%) indicates that test chemical is not persistent in sediments.

 

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 (EPI suite, 2018). If released into the environment, 83.7 % 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:

Bioaccumulation: aquatic/sediments:

Using BCFBAF Program (v3.00) model of EPI suite (2018) the estimated bio concentration factor (BCF) for test chemical is 3.162 L/kg wet-wt at 25 deg. c which does not exceed the bioconcentration threshold of 2000. Therefore it is concluded that test chemical  is non-bioaccumulative in food chain.

Transport and distribution:

Adsorption/ desorption:

The Soil Adsorption Coefficient i.e. Koc value of test chemical  was estimated using EPI suite KOCWIN Program (v2.00) as 260 L/kg (log Koc= 2.094 ) by means of MCI method at 25 deg. C.  This log Koc value indicates that test chemical has low sorption to soil and therefore test chemical has moderate migration potential to ground water.

Additional information

Stability:

Hydrolysis

Various studies have been reviewed to determine the half-life of the test chemical. The studies are as mentioned below:

In first study, the hydrolysis rate constant of chemical obtained was 2.9X10+9 L/mol-sec L/mol/sec. The half-life of hydrolysis obtained at pH 7 was 276 days. Since half-life of hydrolysis is more than 10 days so it is concluded that test chemical shows negligible hydrolysis that means it is not hydrolysable.

In another study, the half-life of hydrolysis obtained at pH 2.96, 7, and 10.95 at 25 deg C was 11.11, 11, and 10.73 year respectively. Since half-life of hydrolysis is more than 10 days so it is concluded that test chemical shows negligible hydrolysis. Thus it is concluded as 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 276 days at pH 7 and was 11.11, 11, and 10.73 year at pH 2.96, 7, and 10.95 respectively at 25 deg C. Thus, based on this half-life value, it can be concluded that the test chemical is not hydrolysable.

Biodegradation:

Biodegradation in water

Various experimental studies have been investigated for the test chemical along with the predicted data for reviewing the biodegradation endpoint which have been summarized as below;

 

In a prediction using the Estimation Programs Interface Suite (2018), the biodegradation potential of the test compoundchemicalin 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 the test chemical is expected to be not readily biodegradable.

 

The above result was supported by Biodegradation study conducted for 28 days for evaluating the percentage biodegradability of test substance. 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 be1.1 and <0% by BOD, O2 consumption, TOC removal, test mat. analysis and UV-Vis parameter in 28 days. Thus, based on percentage degradation, the test substance was considered to be not readily biodegradable in nature.

 

The above results were further supported by the Biodegradation study conducted for 14 days for evaluating the percentage biodegradability of test substance. 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 test 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, the test chemical was considered to be not readily biodegradable in nature.

 

Based on the available data,it can be concluded that the testchemical can be expected to be not readily biodegradable in nature.

 

Biodegradation in water and sediment

Estimation Programs Interface (EPI Suite, 2018) prediction model was run to predict the half-life in water and sediment for the test compound. The Test chemical If released in to the environment, 29% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of the chemical in water is estimated to be 15 days (360 hrs.)The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is low whereas the half-life period of Test chemical in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into sediment is less than 1 %( i.e., reported as 0.0692%) indicates that test chemical is not persistent in sediments.

 

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 (EPI suite, 2018). If released into the environment, 83.7 % 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:

Bioaccumulation: aquatic/sediments:

Different studies have been reviewed for Bioaccumulation in aquatic organisms endpoint for test chemical and its read across chemicals and their results are summarized below.

In first study bio concentration factor (BCF) of test chemical was estimated by using BCFBAF Program (v3.00) model of EPI suite (2018) the estimated bio concentration factor (BCF) for test chemical was 3.162 L/kg wet-wt at 25 deg. c .

Next study was reviewed from authoritative database (HSDB) in this study the BCF value of test chemical estimated was 3.0 dimensionless by using a log Kow of 0.97 and a regression derived equation.

Another study was also reviewed from authoritative database (HSDB) in this study the BCF value of test chemical was estimated to be 30 dimensionless by using a measured water solubility and a recommended regression-derived equation.

By considering the results of all the studies mentioned above it is concluded that BCF value of test chemical is in range of 3.162 -30 dimensionless and this range BCF value is far less than 2000 criteria of CLP regulation. On the basis of this range BCF value it is concluded that test chemical is non-bioaccumulative.

Transport and distribution:

Adsorption/desorption:

Different studies have been reviewed for Adsorption endpoint for test chemical and its read across chemicals and their results are summarized below.

In first study the Soil Adsorption Coefficient i.e. Koc value of test chemical  was estimated using EPI suite KOCWIN Program (v2.00) as 260 L/kg (log Koc= 2.094 ) by means of MCI method at 25 deg. C.  

To support the result of above study another study was reviewed from authoritative database (HSDB) in this study 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 260 dimensionless (Log Koc = 2.4149).

Last study was also reviewed from same source as mentioned above (HSDB) in this study the adsorption coefficient (Koc) value was calculated using a measured water solubility of 200 mg/l and a regression-derived equation. The adsorption coefficient (Koc) value of test substance was estimated to be 240 dimensionless (Log Koc = 2.3802).

By considering the results of all the studies mentioned above it is concluded that Log Koc value of test chemical is in range of 2.094- 2.4149 and this range log Koc value indicates that the substance has a low sorption to soil and sediment and therefore has moderate migration potential to ground water.