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Biodegradation in water

Biodegradability of 5-methyl-3-phenyl-1,2-oxazole-4-carbonyl chloride (CAS no. 16883 -16 -2) is predicted using QSAR toolbox version 3.3 (2017) with logKow as the primary descriptor. Test substance undergoes 0.74% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 5 -methyl-3 -phenyl-1,2 -oxazole-4 -carbonyl chloride was estimated to be not readily biodegradable in water.

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  5 -methyl-3 -phenyl-1,2 -oxazole-4 -carbonyl chloride (CAS No. 16883 -16 -2). If released in to the environment, 16% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 5-methyl-3-phenyl-1,2-oxazole-4-carbonyl chloride in water is estimated to be 37.5 days (900 hrs). The half-life (37.5 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 5 -methyl-3 -phenyl-1,2 -oxazole-4-carbonyl chloride in sediment is estimated to be 337.5 days (8100 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.494%), indicates that 5-methyl-3-phenyl-1,2-oxazole-4-carbonyl chloride is not persistent in sediment.

 

Biodegradation in soil

The half-life period of 5-methyl-3-phenyl-1,2-oxazole-4-carbonyl chloride (CAS No. 16883 -16 -2) 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, 83.1% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 5-methyl-3-phenyl-1,2-oxazole-4-carbonyl chloride in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of 5 -methyl-3 -phenyl-1,2 -oxazole-4 -carbonyl chloride, 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

Biodegradation in water

Various predicted data for the target compound 5-methyl-3-phenyl-1,2-oxazole-4-carbonyl chloride (CAS No. 16883-16-2) and supporting weight of evidence studies for its read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In a prediction done by SSS (2017) using OECD QSAR toolbox version 3.4 with logKow as the primary descriptor, percentage biodegradability of test chemical 5-methyl-3 -phenyl-1,2 -oxazole-4 -carbonyl chloride(CAS No. 16883-16-2) was estimated.Test substance undergoes 0.74% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 5-methyl-3-phenyl-1,2-oxazole-4-carbonyl chloride was estimated to be not readily biodegradable in water.

 

In another prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound 5 -methyl-3 -phenyl-1,2 -oxazole-4 -carbonyl chloride(CAS No. 16883-16-2) 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 chemical 5 -methyl-3 -phenyl-1,2 -oxazole-4 -carbonyl chloride is expected to be not readily biodegradable.

 

In a supporting weight of evidence study from authoritative database (J-CHECK, HSDB, 2017 and EnviChem, 2014) and from secondary source (OECD SIDS, 1998) for the read across chemical 2-Phenylpropene (CAS no. 98-83-9),biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability of read across substance 2-Phenylpropene. The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I) under aerobic conditions. Activated sludge (non-adapted) 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 substance 2-Phenylpropene was determined to 0% by using BOD parameter in 14 days. Thus, based on percentage degradation, 2-Phenylpropene is considered to be not readily biodegradable in nature.

 

Another biodegradation study was conducted for 20 days for evaluating the percentage biodegradability of read across substance 1-methyl-2-vinylbenzene (CAS no. 25013-15-4) under aerobic conditions (HSDB, 2017). Domestic sewage (non-adapted) was used as a test inoculums for the study. The percentage degradation of test substance 1-methyl-2-vinylbenzene was determined to 13% in the first 15 days and 32% degradation in between 15-20 days by using Test mat. analysis parameter. Thus, based on percentage degradation, 21-methyl-2-vinylbenzene is considered to be not readily biodegradable in nature.

 

For the read across chemical (1-bromoethenyl)benzene (CAS no. 98-81-7) from authoritative database (J-CHECK, 2017), biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance (1-bromoethenyl)benzene. 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 substance (1-bromoethenyl)benzene was determined to 0 and 77% degradation by BOD and GC parameter in 28 days. Thus, based on percentage degradation (0% by using BOD parameter), (1-bromoethenyl)benzene is considered to be not readily biodegradable in nature.

 

On the basis of above results for target chemical5-methyl-3-phenyl-1,2-oxazole-4-carbonyl chloride(from OECD QSAR toolbox version 3.3 and EPI suite, 2017) and for its read across substance (from authoritative database J-CHECK, HSDB & EnviChem and secondary source OECD SIDS), it can be concluded that the test substance 5 -methyl-3 -phenyl-1,2 -oxazole-4 -carbonyl chloridecan be expected to be not 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  5 -methyl-3 -phenyl-1,2 -oxazole-4 -carbonyl chloride (CAS No. 16883 -16 -2). If released in to the environment, 16% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 5-methyl-3-phenyl-1,2-oxazole-4-carbonyl chloride in water is estimated to be 37.5 days (900 hrs). The half-life (37.5 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 5 -methyl-3 -phenyl-1,2 -oxazole-4-carbonyl chloride in sediment is estimated to be 337.5 days (8100 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.494%), indicates that 5-methyl-3-phenyl-1,2-oxazole-4-carbonyl chloride is not persistent in sediment.

 

Biodegradation in soil

The half-life period of 5-methyl-3-phenyl-1,2-oxazole-4-carbonyl chloride (CAS No. 16883 -16 -2) 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, 83.1% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 5-methyl-3-phenyl-1,2-oxazole-4-carbonyl chloride in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of 5 -methyl-3 -phenyl-1,2 -oxazole-4 -carbonyl chloride, 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 5-methyl-3-phenyl-1,2-oxazole-4-carbonyl chloride can be considered to be not readily biodegradable in nature.