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Environmental fate & pathways

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Biodegradation in water:

Estimation Programs Interface Suite (EPI 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 chemical is expected to be not readily biodegradable.

Biodegradation in water and sediments:

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, 90.7 % 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 360 days (8640 hrs). Based on this half-life value of test chemical, it is concluded that the chemical is persistent in the soil environment and the exposure risk to soil dwelling animals is high.

Biodegradation in water:

Estimation Programs Interface (EPI Suite, 2018) prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 3.55 % 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 180 days (4320 hrs). The half-life (180 days estimated by EPI suite) indicates that the chemical is persistentin water and the exposure risk to aquatic animals is high whereas the half-life period of test chemical in sediment is estimated to be 1620.833 days (38900  hrs). However, as the percentage release of test chemical into the sediment is less than 6% (i.e, reported as 5.72 %), indicates that test chemical is not persistent in sediment.

Additional information

Biodegradation in water:

Predicted data study and experimental studies have been done for biodegradation of test chemical and its read across chemicals in water and their results are summarized below.

In first study prediction was done by using Estimation Programs Interface Suite (EPI 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 chemical is expected to be not readily biodegradable.

Nex study was experimental study in this Biodegradation experiment was conducted for 5 days for evaluating the percentage biodegradability of test substance using standard dilution method under aerobic conditions at a temperature of 20°C. Sewage was used as a test inoculum. The 5 day BOD value of test chemical was determined to be 0 g/g. Thus, based on this value, test chemical is considered to be not readily biodegradable in nature.

Last study was also experimental study in this 28-days Closed Bottle test following the OECD guideline 301 Dwas performed to determine the ready biodegradability of the test item. 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. 1 polyseed capsule were added in 500 ml D.I water and then stirred for 1 hour for proper mixing and functioning of inoculum. This gave the bacterial count as 107 to 108 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism. 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 73.49%. Degradation of Sodium Benzoate exceeds 31.32% on 7 days & 49.39 on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 0.52 mgO2/mg. ThOD was calculated as 2.44 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 21.31%. Based on the results, the test item, under the test conditions, was not readily biodegradable in nature.

By considering results of all the studies mentioned above it is concluded that test chemical is not readily biodegradable in water.

Biodegradation in water and sediments:

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, 90.7 % 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 360 days (8640 hrs). Based on this half-life value of test chemical, it is concluded that the chemical is persistent in the soil environment and the exposure risk to soil dwelling animals is high.

Biodegradation in water:

Estimation Programs Interface (EPI Suite, 2018) prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 3.55 % 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 180 days (4320 hrs). The half-life (180 days estimated by EPI suite) indicates that the chemical is persistentin water and the exposure risk to aquatic animals is high whereas the half-life period of test chemical in sediment is estimated to be 1620.833 days (38900  hrs). However, as the percentage release of test chemical into the sediment is less than 6% (i.e, reported as 5.72 %), indicates that test chemical is not persistent in sediment.