Methyl 5-nitrohydrogen.isophthalate

Endpoint summary

Description of key information

Hydrolysis

HYDROWIN v2.00 program of Estimation Programs Interface (2018) prediction model was used to predict the hydrolysis half-life of test chemical. The estimated half-life of test chemical was evaluated to be 10.315 days at pH 7.0 and 1.032 days at pH 8.0 (at 25ᵒC) respectively. Thus, based on half-life value (at pH 7.0), it indicates 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 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, 29.6% 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 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 moderate to 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 the sediment is less than 1% (i.e, reported as 0.069%), 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, 70.3% 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 30 days (720 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.

Additional information

Hydrolysis

HYDROWIN v2.00 program of Estimation Programs Interface (2018) prediction model was used to predict the hydrolysis half-life of test chemical. The estimated half-life of test chemical was evaluated to be 10.315 days at pH 7.0 and 1.032 days at pH 8.0 (at 25ᵒC) respectively. Thus, based on half-life value (at pH 7.0), it indicates that the test chemical is not hydrolysable in water.

 

Hydrolysis endpoint can also be considered for waiver as per in accordance with column 2 of Annex VIII of the REACH regulation, testing for this endpoint is scientifically not necessary and does not need to be conducted since the test chemical is readily biodegradable in water.

Biodegradation in water

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

 

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

 

In a supporting weight of evidence study from study report (2018) for the test chemical,28-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test chemical. The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used for this study. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32 ml/l. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 75.3%. Degradation of Sodium Benzoate exceeds 46.38% on 7 days & 61.44% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 0.77 mgO2/mg. ThOD was calculated as 1.05 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 73.33%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

 

Another biodegradation study using a batch test in an open system was conducted for 20 days for evaluating the biodegradability of test chemical (from peer reviewed journal, handbook authoritative databases and secondary source, 2017). Adapted activated sludge was used as a test inoculum obtained from a sewage plant is cultivated in a1000ml volumetric cylinder. The mixture is aerated with pressure air. Every day 200 ml of the mixture is driven off so that the sludge age is 5 days. After driving off the 200ml of the mixture aeration is interrupted, and after sedimentation ca.600ml of the liquid phase is driven off. The residue (200 ml of the thickened activated sludge) is diluted with tap water to the volume ofca.800 ml and 600 mg/l of starch or glucose, 600 mg/l of peptone, 25 ml of a phosphate buffer pH 7.2, and the solution of the tested compound are added. Then the mixture in the cylinder is made up to 1000ml with tap water and aerated for 23 h (the recirculation ratio is 0-25). After this period the procedure is repeated. Test chemical conc. used for the study was 200 mg/l based on COD. To 1000-1500ml of the biological medium such amount of the solution of the substance tested is added that the initial COD is 200 mg/l. Then such an amount of the adapted activated sludge, washed and thickened by sedimentation, is dosed to the medium that the concentration of the dry matter is 100 mg/l. Simultaneously, a blank test is prepared. The beaker is placed in a dark room with a roughly 3 constant temperature of 20±3°C on an electromagnetic stirrer and a pH of 7.2 for 120 hrs. The initial value of COD or organic carbon of the liquid phase are determined. Samples filtered or centrifuged before analysis, are taken at suitable intervals. The decrease of the tested substance in the liquid phase is evaluated by determining COD or organic carbon. The results are compared with those of a blank test and standard compound decomposition. With the degree of degradation also the average specific rate of degradation is determined, expressed in terms of mg COD (or organic carbon) removed by a gram of dry matter of the activated sludge per hour. The percentage degradation of test chemical was determined to be 93.4% by using COD removal parameter in < 20 days. Thus, based on percentage degradation, test chemical was considered to be readily biodegradable in nature.

 

For the test chemical from authoritative databases and secondary source, biodegradation study was conducted for 14 days for evaluating the percentage biodegradability of test chemical. The study was performed according toOECD 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 99, 96 and 100% by BOD, TOC removal and HPLC parameter in 14 days. Thus, based on percentage degradation, test chemical is considered to be readily biodegradable in nature.

 

On the basis of above results of the test chemical, it can be concluded that the test chemical can be expected to be 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, 29.6% 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 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 moderate to 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 the sediment is less than 1% (i.e, reported as 0.069%), 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, 70.3% 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 30 days (720 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 readily biodegradable in nature.