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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 chemical is expected to be not readily biodegradable.

Additional information

Biodegradation in water

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

 

In a prediction done using the Estimation Programs Interface Suite, the biodegradation potential of the test chemical in the presence of mixed populations of environmental microorganisms was predicted. 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.

 

In a supporting weight of evidence study from study report, biodegradation study was conducted for 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. 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 10E7 to 10E8 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 72.28%. Degradation of Sodium Benzoate exceeds 63.25% on 7 days & 69.27% 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 0.4 mgO2/mg. ThOD was calculated as 1.31 mgO2/mg. Accordingly, the % degradation of the test chemical after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 30.53%. Based on the results, the test chemical, under the test conditions, was considered to be not biodegradable in nature.

 

For the test chemical, biodegradation study (H. Heukelekian et. al., 1955) was conducted for 5 days for evaluating the percentage biodegradability of test chemical 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.

 

On the basis of the overall results, it can be concluded that the test chemical was considered to be not readily biodegradable in water.