Methyl N-(2,6-dimethylphenyl)-DL-alaninate

Endpoint summary

Description of key information

Biodegradation in water

Biodegradability of 2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester (CAS no. 52888 -49 -0) is predicted using QSAR toolbox version 3.3 (2017) with logKow as the primary descriptor. Test substance undergoes 0.166% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester 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 2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester (CAS No. 52888 -49 -0). If released in to the environment, 21.6% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester 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 2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester 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 0.228%), indicates that 2 -(2,6 -dimethyl-phenylamino)- propionic acid methyl ester is not persistent in sediment.

 

Biodegradation in soil

The half-life period of 2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester (CAS No. 52888 -49 -0) 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, 78% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 2 -(2,6 -dimethyl- phenylamino)-propionic acid methyl ester in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of 2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester, 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.

Additional information

Biodegradation in water

Various predicted data for the target compound 2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester (CAS No. 52888-49-0) and supporting weight of evidence studies for its structurally similar read across substance 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 chemical 2 -(2,6 -dimethyl- phenylamino)-propionic acid methyl ester(CAS No. 52888-49-0) was estimated.Test substance undergoes 0.166% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical2-(2,6-dimethyl-phenylamino)-propionic acid methyl esterwas 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 compound-(2,6-dimethyl-phenylamino)-propionic acid methyl ester(CAS No. 52888-49-0) 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 chemical2-(2,6-dimethyl-phenylamino)-propionic acid methyl esteris expected to be not readily biodegradable.

 

In a supporting weight of evidence study from authoritative database (J-CHECK and HSDB, 2017 & EnviChem, 2014) for the read across chemical 3,4-dimethylaniline (CAS no. 95-64-7),biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance 3,4-dimethylaniline. The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)). Concentration of inoculum i.e, sludge used was 100 mg/l and initial test substance conc. used in the study was 30 mg/l, respectively. The percentage degradation of substance 3,4-dimethylaniline was determined to be 7.1 and 4.8% by BOD and GC parameter in 28 days. Thus, based on percentage degradation, 3,4 -dimethylaniline is considered to be not readily biodegradable in nature.

 

For the read across chemical 2,6-Xylidine (CAS no. 87-62-7) from authoritative database (J-CHECK and HSDB, 2017) and secondary source (OECD SIDS, 2012), biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance 2,6-Xylidine (CAS no. 87-62-7). The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)) at a temperature of 25°C. Activated sludge, non-adapted was used as a test inoculum for the study. Sludge and surface water including surface soil were collected from ten different places in Japan which includes water treatment plants, rivers, lake and inner bays. These sludges and water/soil were mixed and cultivated with glucose and peptone as nutrient in a testing laboratory. 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. For analytical method,10 mL of the test solution was taken out and centrifuged. Then, the supernatant of this solution was employed for the quantitative analysis for HPLC and TOC.BOD was continuously measured by BOD analysis. Direct analysis by HPLC and TOC was conducted after 28 days. Aniline was used as a reference substance for the study. Reference substance aniline undergoes 66% and 78% degradation after 7 and 14 days, respectively. Thus, based on this, pass level criteria was fulfilled. The percentage degradation of substance 2,6-Xylidine was determined to be 0 and 1% by BOD, TOC removal and HPLC parameter in 28 days. Thus, based on percentage degradation, 2,6-Xylidine is considered to be not readily biodegradable in nature.

 

Another biodegradation study was conducted for 70 days for evaluating the percentage biodegradability of read across substance 2,6-Xylidine (CAS no. 87-62-7) (HSDB, 2017). The study was performed according to OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test) under aerobic conditions. Initial test substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of read across substance 2,6-Xylidine was determined to be 4, 8, 25, 38 and 69% by BOD parameter after 7, 13, 36, 42 and 70 days, respectively. Thus, based on percentage degradation, 2,6-Xylidine is considered to be not readily biodegradable in nature.

 

In a supporting weight of evidence study from authoritative database (J-CHECK, 2017) and secondary source (OECD SIDS, 2012) for the read across chemical 2,3-Xylidine (CAS no. 87-59-2),biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance 2,3-Xylidine. The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)) at a temperature of 25± 1°C. Activated sludge, non-adapted was used as a test inoculum for the study. Sludge and surface water including surface soil were collected from ten different places in Japan which includes water treatment plants, rivers, lake and inner bays. These sludges and water/soil were mixed and cultivated with glucose and peptone as nutrient in a testing laboratory. 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. For analytical method, After the cultivation period, 10 mL of the test substance was taken out. Then this test solution was centrifuged with 1000 g for 10 minutes. The supernatant was then analyzed with TOC and HPLC.BOD was continuously measured by BOD analysis. Direct analysis by HPLC and TOC was conducted after 28 days. Aniline was used as a reference substance for the study. Inoculum blank was also setup for the biodegradation study. Reference substance aniline undergoes 59% and 76% degradation after 7 and 14 days, respectively. Thus, based on this, pass level criteria was fulfilled. The percentage degradation of substance 2,3-Xylidine was determined to be 3 and 0% by BOD, TOC removal and HPLC parameter in 28 days. Thus, based on percentage degradation, 2,3-Xylidine is considered to be not readily biodegradable in nature.

 

On the basis of above results for target chemical2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester(from OECD QSAR toolbox version 3.3 and EPI suite, 2017) and for its read across substance (authoritative database J-CHECK, HSDB, EnviChem and secondary source OECD SIDS), it can be concluded that the test substance 2 -(2,6 -dimethyl-phenyl amino)-propionic acid methyl ester can 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 2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester (CAS No. 52888 -49 -0). If released in to the environment, 21.6% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester 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 2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester 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 0.228%), indicates that 2 -(2,6 -dimethyl-phenylamino)- propionic acid methyl ester is not persistent in sediment.

 

Biodegradation in soil

The half-life period of 2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester (CAS No. 52888 -49 -0) 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, 78% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 2 -(2,6 -dimethyl- phenylamino)-propionic acid methyl ester in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of 2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester, 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 2-(2,6-dimethyl-phenylamino)-propionic acid methyl ester can be considered to be not readily biodegradable in nature.