N,N-dimethyl-p-toluidine

Endpoint summary

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 at a temperature of 25°C or 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 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 was expected to be not readily biodegradable.

Biodegradation in water:simulation testing:

Estimation Programs Interface prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 21.8 % 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 was estimated to be 37.5 days (900 hrs). The half-life (37.5 days estimated by EPI suite) indicates that the chemical was not persistent in water and the exposure risk to aquatic animals is moderate to low.

 

Biodegradation in sediment simulation testing:

Estimation Programs Interface prediction model was run to predict the half-life in sediment for the test chemical. The half-life period of test chemical in sediment was 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 0.175%), indicates that the test chemical was 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. If released into the environment, 78% of the test chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil was 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

The bioaccumulation study in fish was conducted for estimating the BCF (bioaccumulation factor) value of test chemical. The bioaccumulation BCF value was calculated using a log Kow of 2.81 and a regression-derived equation. The estimated BCF (bioaccumulation factor) value of test chemical was determined to be 33 dimensionless, which does not exceed the bioconcentration threshold of 2000, indicating that the test chemical was considered to be non-accumulative in aquatic organisms.

Adsorption / desorption

Adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical. The adsorption coefficient (Koc) value was calculated using a log Kow of 2.81 and a regression derived equation. The adsorption coefficient (Koc) value of test chemical was estimated to be 260 (Log Koc = 2.414). This Koc value indicates that the test chemical has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

Additional information

Hydrolysis:

Data from various sources for the test chemical and structurally and functionally similar read across chemicals were reviewed for the hydrolysis end point study which are summarized as 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 of 4, 7 and 9, respectively. The half-life value of test chemical was determined to be > 1 yr at pH 4, 7 and 9, respectively at a temperature of 25⁰ C. Thus, based on this result, test chemical was considered to be non-hydrolysable.

 

Above data further supported by the data obtained from the secondary sources. The half-life of the test chemical was determined at different pH range. The preliminary study was performed according to OECD Guideline 111 (Hydrolysis as a Function of pH) at a temperature of 50°C. Initial test chemical concentration used for the study was 20 mg/l. Analytical method involve the use of HPLC. Although the half-life value of test chemical was not known, but at the preliminary test, 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 50 ⁰ C and at pH 4, 7 and 9, respectively. Based on the half-life values, it was concluded that the test chemical was non hydrolysable.

 

Thus, based on the above all studies and result observation, test chemical was considered to be non-hydrolysable.  

Biodegradation in water:

Various predicted and experimental studies of the test chemical and supporting its structurally and functionally similar read across substances were reviewed for the biodegradation end point which are summarized as below:

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 was expected to be not readily biodegradable.

 

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test chemical. Activated sludge was used as a test inoculum for the study. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance concentration used in the study was 100 mg/l, respectively. The percentage degradation of test chemical was determined to be 2% by BOD, TOC removal and HPLC parameter in 28 days. Thus, based on percentage degradation by various parameters, test chemical was considered to be not readily biodegradable in nature.

 

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test chemical. The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test). Activated sludge was used as a test inoculum for the study. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance concentration used in the study was 100 mg/l, respectively. The percentage degradation of test chemical was determined to be 0, 6 and 1% by BOD, TOC removal and HPLC parameter in 28 days. Thus, based on percentage degradation, test chemical was considered to be not readily biodegradable in nature.

Based on 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:simulation testing:

Estimation Programs Interface prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 21.8 % 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 was estimated to be 37.5 days (900 hrs). The half-life (37.5 days estimated by EPI suite) indicates that the chemical was not persistent in water and the exposure risk to aquatic animals is moderate to low.

 

Biodegradation in sediment simulation testing:

Estimation Programs Interface prediction model was run to predict the half-life in sediment for the test chemical. The half-life period of test chemical in sediment was 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 0.175%), indicates that the test chemical was 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. If released into the environment, 78% of the test chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil was 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

Data from various sources for the test chemical were reviewed for the bioaccumulation end point which are summarized as below:

 

The bioaccumulation study in fish was conducted for estimating the BCF (bioaccumulation factor) value of test chemical. The bioaccumulation BCF value was calculated using a log Kow of 2.81 and a regression-derived equation. The estimated BCF (bioaccumulation factor) value of test chemical was determined to be 33 dimensionless, which does not exceed the bioconcentration threshold of 2000, indicating that the test chemical was considered to be non-accumulative in aquatic organisms.

 

Above data further supported by the data obtained from secondary source. The bioaccumulation study on aquatic organisms was conducted for estimating the BCF (bioaccumulation factor) value of test chemical. The bioaccumulation factor (BCF) value was calculated using a log Kow of 2.81 and an equation. The estimated BCF value of the test chemical was determined to be 29.09 dimensionless, which does not exceed the bioconcentration threshold of 2000, indicating that the test chemical was considered to be non-bioaccumulative in aquatic organisms.

 

Similar BCFBAF model of Estimation Programs Interface was used to predict the bioconcentration factor (BCF value) of the test chemical. The bioconcentration factor (BCF) of test chemical was estimated to be 33.19 L/kg whole body w.w (at 25 °C) which does not exceed the bio concentration threshold of 2000, indicating that the test chemical was not expected to bioaccumulate in the food chain.

 

On the basis of above results for test chemical, it can be concluded that the BCF value of test chemical was ranges from 29.09 to 33.19,which does not exceeds the bioconcentration threshold of 2000, indicating that the test chemical was not expected to bioaccumulate in the food chain.

 

Adsorption:

Data from various sources for the test chemical and structurally and functionally similar read aacross chemicals were reviewed for the adsorption end point which are summarized as below:

 

Adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical. The adsorption coefficient (Koc) value was calculated using a log Kow of 2.81 and a regression derived equation. The adsorption coefficient (Koc) value of test chemical was estimated to be 260 (Log Koc = 2.414). This Koc value indicates that the test chemical has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

KOCWIN model 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 126.2 L/kg with log Koc value of 2.1011 by means of MCI method at 25°C. This Koc value indicates that the test chemical has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

Similarly, the Soil Adsorption Coefficient i.e Koc value of test chemical was estimated using predicted database. The adsorption coefficient i.e. Koc value of the test chemical was estimated to be 332.40 (Log Koc was 2.52) at pH 5.5 and 770.34 (Log Koc was 2.88) at pH 7.4, respectively. This Koc value indicates that the test chemical has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.

Above studies further supported by the weight of evidence study from authoritative databases. The adsorption study was conducted for determining the adsorption coefficient (Koc) value of test chemical. The study was performed using 4 silt loam soils over a pH ranging from 6.1 to 7.5, respectively. The adsorption coefficient (Koc) value of test chemical was determined to be 44 dimensionless (Log Koc = 1.643). This Koc value indicates that the test chemical has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

Thus, based on the above all studies and Koc value observation, it was concluded that the test chemical has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.