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Biodegradation in water

Biodegradation study was conducted according to CO2 generation amount method for evaluating the percentage biodegradability of test substance 2 -hydroxy-1H-isoindole-1,3(2H)-dione (CAS no. 524 -38 -9) (Scifinder, American Chemical Society, 2017).The final aerobic percentage degradation rate of test substance was determined to be 95.80% degradation by CO2 evolution parameter in a 14 day period. Thus, based on percentage degradation, 2 -hydroxy-1H-isoindole-1,3(2H)-dione is considered to be 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 -hydroxy-1H-isoindole-1,3(2H)-dione (CAS No. 524 -38 -9). If released in to the environment, 30.7% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 2 -hydroxy-1H-isoindole-1,3(2H)-dione in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the 2 -hydroxy-1H-isoindole-1,3(2H)-dione is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of 2 -hydroxy-1H-isoindole-1,3(2H)-dione in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of 2 -hydroxy-1H-isoindole-1,3(2H)-dione into the sediment is less than 1% (i.e, reported as 0.0691%), indicates that 2 -hydroxy-1H-isoindole-1,3(2H)-dione is not persistent in sediment.

Biodegradation in soil

The half-life period of test chemical2-hydroxy-1H-isoindole-1,3(2H)-dione(CAS No. 524-38-9) 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, 69.2% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of2-hydroxy-1H-isoindole-1,3(2H)-dionein soil is estimated to be 30 days (720 hrs). Based on this half-life value of2-hydroxy-1H-isoindole-1,3(2H)-dione, 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

From BCFBAF (v3.00) model of EPI suite and PBT profiler the estimated bio concentration factor (BCF) for 2-hydroxy-1H-isoindole-1,3(2H)-dione is 3.2 L/kg wet-wt which does not exceed the bioconcentration threshold of 2000.Thus it is concluded that 2-hydroxy-1H-isoindole-1,3(2H)-dione is not expected to bio accumulate in the aquatic environment.

Adsorption / desorption

The Soil Adsorption Coefficient i.e Koc value of 2-hydroxy-1H-isoindole-1,3(2H)-dione was estimated using EPI suite KOCWIN (v2.00) as Koc 10 L/kg (log Koc = 1)  by means of MCI method at 25 deg.C. This Koc value indicates that the substance 2-hydroxy-1H-isoindole-1,3(2H)-dione has a negligible sorption to soil and sediment and therefore have rapid migration potential to groundwater.

Additional information

Biodegradation in water

Various study and predicted data for the target compound 2-hydroxy-1H-isoindole-1,3(2H)-dione (CAS No. 524-38-9) and various supporting studies for its read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental key study, biodegradation experiment was conducted according to CO2 generation amount method for evaluating the percentage biodegradability of test substance 2 -hydroxy-1H-isoindole-1,3(2H)-dione (CAS no. 524 -38 -9) (Scifinder, American Chemical Society, 2017). The final aerobic percentage degradation rate of test substance was determined to be 95.80% degradation by CO2 evolution parameter in a 14 day period. Thus, based on percentage degradation, 2 -hydroxy-1H-isoindole-1,3(2H)-dione is considered to be readily biodegradable in nature.

 

In a supporting study from secondary source (Scifinder, American Chemical Society, 2017), biodegradation experiment was performed according to the shaking cultivation method for evaluating the percentage biodegradability of test substance 2 -hydroxy-1H-isoindole-1,3(2H)-dione (CAS no. 524 -38 -9). The primary aerobic percentage degradation rate of test substance was determined to be 93.60% degradation in a 5 day period. Thus, based on percentage degradation, 2 -hydroxy-1H-isoindole-1,3(2H)-dione is considered to be readily biodegradable in nature.

 

For target chemical 2-hydroxy-1H-isoindole-1,3(2H)-dione(CAS No. 524-38-9), biodegradability of2-hydroxy-1H-isoindole-1,3(2H)-dioneis predicted using OECD QSAR toolbox version 3.4 with logKow as the primary descriptor (2017).Test substance undergoes 73.63% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 2-hydroxy-1H-iso indole-1,3(2H)-dione was estimated to be readily biodegradable in water.

 

In a supporting study from authoritative database (J-CHECK, 2016), biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability of read across substance1H-isoindole-1,3(2H)-dione(CAS no. 85 -41 -6). 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 92, 94 and 100% by BOD(NH3), TOC removal and HPLC parameter in 14 days. Thus, based on percentage degradation, 1H-isoindole-1,3(2H)-dione is considered to be readily biodegradable in nature.

 

For another read across chemical 2 -bentzofuran-1,3 -dione (CAS no. 85 -44 -9),biodegradation study was conducted for 14 days for evaluating the percentage biodegradability of read across substance 2 -bentzofuran-1,3 –dione(J-CHECK, 2016). 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 85.2, 93 and 96.4% degradation by BOD, TOC removal and UV-Vis parameter in 14 days. Thus, based on percentage degradation, 2 -bentzofuran-1,3 -dione is considered to be readily biodegradable in nature.

 

Another biodegradation study for the same read across substance 2 -bentzofuran-1,3 -dione (CAS no. 85 -44 -9) was conducted for 30 days for evaluating the percentage biodegradability of substance 2 -bentzofuran-1,3 -dione(HSDB and OECD SIDS, 2016). The study was performed according to OECD Guideline 301 D “Ready Biodegradability: Closed Bottle Test”. Concentration of inoculum i.e, sludge used was 3 mg/l and initial test substance conc. used in the study was 1000 mg/l, respectively. The percentage degradation of read across substance was determined to be 45, 58 and 71% by BOD parameter after 5, 10 and 30 days, respectively. Thus, based on percentage degradation, 2 -bentzofuran-1,3 -dione is considered to be readily biodegradable in nature.

 

On the basis of above results for target chemical 2-hydroxy-1H-isoindole-1,3(2H)-dione (from secondary source Scifinderand OECD QSAR toolbox version 3.4, 2017) and for its read across substance (from authoritative database J-CHECK, HSDB and secondary source OECD SIDS, 2016), it can be concluded that the test substance2-hydroxy-1H-isoindole-1,3(2H)-dionecan be expected to be 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 -hydroxy-1H-isoindole-1,3(2H)-dione (CAS No. 524 -38 -9). If released in to the environment, 30.7% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 2 -hydroxy-1H-isoindole-1,3(2H)-dione in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the 2 -hydroxy-1H-isoindole-1,3(2H)-dione is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of 2 -hydroxy-1H-isoindole-1,3(2H)-dione in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of 2 -hydroxy-1H-isoindole-1,3(2H)-dione into the sediment is less than 1% (i.e, reported as 0.0691%), indicates that 2 -hydroxy-1H-isoindole-1,3(2H)-dione is not persistent in sediment.

Biodegradation in soil

The half-life period of test chemical2-hydroxy-1H-isoindole-1,3(2H)-dione(CAS No. 524-38-9) 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, 69.2% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of2-hydroxy-1H-isoindole-1,3(2H)-dionein soil is estimated to be 30 days (720 hrs). Based on this half-life value of2-hydroxy-1H-isoindole-1,3(2H)-dione, 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-hydroxy-1H-isoindole-1,3(2H)-dione can be considered to bereadily biodegradable in nature.

Bioaccumulation: aquatic / sediment

Four studies including all predicted data from validated models and experimental data from authorative database for bioaccumulation (BCF) endpoint of target chemical 2-hydroxy-1H-isoindole-1,3(2H)-dione (Cas no. 524-38-9) with relevant read across which is structurally similar to target were summarized as follows: 

 

First prediction done using BCFBAF (v3.00) model and PBT profiler which indicate the estimated bio concentration factor (BCF) for 2-hydroxy-1H-isoindole-1,3(2H)-dione is 3.2 L/kg wet-wt which does not exceed the bioconcentration threshold of 2000. Thus it is concluded that the substance is not expected to bio accumulate in the aquatic environment.

 

Above prediction is supported by data from Scifinder database which suggest the Bioconcentration factor (BCF) for target chemical 2-hydroxy-1H-isoindole-1,3(2H)-dione to be 6.32 to 6.37 at pH range 1-4, 5.90 at pH 5, 3.55  at pH 6, 1.0 at pH range 7-10 and temperature 25 deg.C.Based on the BCF concentration at all range of pH it is concluded that the test chemical 2-hydroxy-1H-isoindole-1,3(2H)-dione is non bioaccumulative in nature as it does not exceed the BCF criteria of 2000.

 

And Chemspider - ACD/PhysChem Suite prediction model indicate the Bioconcentration factor (BCF) for target chemical 2-hydroxy-1H-isoindole-1,3(2H)-dione to be 1.54 at pH 5.5 and 1 at pH 7.4 at temperature 25 deg.C. Based on the BCF concentration at two different pH concluded that the test chemical 2-hydroxy-1H-isoindole-1,3(2H)-dione is non bioaccumulative in nature as it does not exceed the BCF criteria of 2000.

Above all results for target are further supported by experimental data of read across chemical Phthalimide (Cas no. 85-41-6) wherein an estimated BCF value of 4.4 was calculated for phthalimide, using an experimental log Kow of 1.15 and a recommended regression derived equation. This BCF value suggests that bioconcentration in aquatic organisms will not be an important fate process.(HSDB database by US EPA;2017)

Thus based on all available studies for bioaccumulation endpoint concluded that the test substance 2-hydroxy-1H-isoindole-1,3(2H)-dione (Cas no. 524-38-9) is expected to be non Bioaccumulative in aquatic environment.

Adsorption / desorption

Four different predicted data from validated model and experimental data from authorative database for adsorption (KOC) endpoint of test substance 2-hydroxy-1H-isoindole-1,3(2H)-dione (Cas no. 524-38-9) with relevant read across which is structurally similar to target were summarized as follows: 

 

First estimation using KOCWIN model (v2.00) of EPI suite indicated the Soil Adsorption Coefficient i.e Koc value of 2-hydroxy-1H-isoindole-1,3(2H)-dione as Koc 10 L/kg (log Koc = 1) by means of MCI method at 25 deg.C. This Koc value indicates that the substance 2-hydroxy-1H-isoindole-1,3(2H)-dione has a negligible sorption to soil and sediment and therefore have rapid migration potential to groundwater.

 

Another prediction model for target i.e Chemspider - ACD/PhysChem Suite suggest the soil adsorption coefficient i.e Koc value of test substance 2-hydroxy-1H-isoindole-1,3(2H)-dione was estimated to be 44.58 (log koc: 1.64 ) at pH 5.5 and  temp.25 deg.C this Koc value at 5.5 pH indicates that the substance 2-hydroxy-1H-isoindole-1,3(2H)-dione has negligible sorption to soil and sediment and therefore have rapid to moderate migration potential to groundwater.

Above both results are supported by another prediction database Scifinder, which indicated the soil adsorption coefficient i.e Koc value of test substance 2-hydroxy-1H-isoindole-1,3(2H)-dione was estimated to be 130-131 (Log koc: 2.11) at pH 1-4; 121 (Log koc: 2.08) at pH 5; 73.0 (Log koc:1.86) at pH 6 and 14.7 (Log koc:1.16) at temperature 25 deg.C. This Koc value at all range of pH condition indicates that the substance 2-hydroxy-1H-isoindole-1,3(2H)-dionehas negligible to low sorption to soil and sediment and therefore have rapid to moderate migration potential to groundwater.

Experimental data of read across chemical Phthalimide (Cas no. 85-41-6) give assistance to all three predicted results of target. The result suggest the Koc of phthalimide is estimated as approximately 100, using an experimental log Kow of 1.15 and a regression derived equation.This estimated Koc value suggests that phthalimide should have moderate to high mobility in soil.

Thus all above available values for adsorption (log KOC) is in the range of 1 to 2.11 (L/kg or dimensionless) which concluded that the target substance 2-hydroxy-1H-isoindole-1,3(2H)-dione (Cas no. 524-38-9) is expected to have high mobility in soil and sediment compartment.