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Environmental fate & pathways

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Description of key information

Biodegradation in water: screening test:

The biodegradability of the test substance was calculated using seven different Biowin 1-7 models of the BIOWIN v4.10 software. The results indicate that the test substance was expected to be not readily biodegradable.

Additional information

Biodegradation in water: screening test:

Predicted data for the target compound and supporting weight of evidence studies for its read across substance from study report were reviewed for the biodegradation end point which is summarized as below:

 Estimation Programs Interface Suite (EPI suite, 2017) BIOWIN v4.10 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 the test substance was expected to be not readily biodegradable.

 In a supporting weight of evidence, Manometric respirometry test following the OECD guideline 301F was performed to determine the ready biodegradability of the test substance. The test system included control, test item and reference item. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 100mg/L, while that of inoculum was 10ml/l. ThOD (Theoretical oxygen demand) of test and reference substance was determined by calculation. % Degradation was calculated using the values of BOD and ThOD for test substance and reference substance. The BOD28 value of test substance was observed to be 0.058 mgO2/mg. ThOD was calculated as 0.709 mgO2/mg. Therefore, the % degradation of the test substance after 28 days of incubation at 20 ± 1°C was calculated to be 8.18%. Based on the results, the test substance, under the test conditions, was concluded to be non-biodegradable over a period of 28 days.

 Another, 28-days Manometric respirometry test following the OECD guideline 301F to determine the ready biodegradability of the test chemical was conducted. The study was performed at a temperature of 20± 1°C. Mixture of domestic waste water, surface soil and soil samples was used as a test inoculum for the study. OECD mineral medium was used for the study. The test system included control, test and reference substance. The concentration of test and reference substance (Sodium Benzoate) chosen for both the study was 30mg/L, while that of inoculum was 10mg/L. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. The % degradation of procedure control (Sodium Benzoate) was determined to be 74.074%. The mean BOD value (mg O2/l) in control on 28th day was 9 mg O2/l. Degradation of Sodium Benzoate exceeds 50.050 % after 7 days and 68.068 % after 14 days. The BOD28 value of test chemical was observed to be -0.048mgO2sup>/mg. ThOD was calculated as 0.733 mgO2/mg. Accordingly, the % degradation of the test substance after 28 days of incubation at 20 ± 1°C was determined to be -6.496 %.Based on the results, the test substance under the test conditions, was considered to be not readily biodegradable.

 On the basis of results of above mentioned studies for test chemical, it is concluded that the test chemical can be expected to be not readily biodegradable.