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Environmental fate & pathways

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Biodegradation in water

Biodegradability of 1 -Bromo-3 -methoxybenzene (CAS no. 2398 -37 -0) is predicted using QSAR toolbox version 3.3 (2017). Test substance undergoes 0.125% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 1 -Bromo-3 -methoxybenzene 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 1 -Bromo-3 -methoxybenze ne (CAS No. 2398 -37 -0). If released in to the environment, 35.2% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 1 -Bromo-3 -methoxybenzene 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 1 -Bromo-3 -methoxybenzene 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 0.324%), indicates that 1 -Bromo-3 -methoxybenzene is not persistent in sediment.

Biodegradation in soil

The half-life period of1-Bromo-3-methoxybenzene(CAS No. 2398 -37 -0) 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, 57.9% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of1-Bromo-3-methoxybenzenein soil is estimated to be 75 days (1800 hrs). Based on this half-life value of1-Bromo-3-methoxybenzene, 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

2 predicted data for the target compound 1-Bromo-3-methoxybenzene (CAS No. 2398-37-0) and the total 3 studies (from authoritative database) for its closest read across substances with logKow as the primary descriptor were reviewed for the biodegradation end point which are summarized as below:

 

In a prediction done by SSS (2017) using QSAR toolbox version 3.3 with logKow as the primary descriptor, percentage biodegradability of test chemical 1-Bromo-3 -methoxybenzene (CAS no. 2398 -37 -0) was estimated. Test substance undergoes 0.125% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 1 -Bromo-3 -methoxybenzene 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 1 -Bromo-3 -methoxybenzene (CAS no. 2398 -37 -0) 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 1 -Bromo-3 -methoxybenzene is expected to be not readily biodegradable.

 

In a weight of evidence study from authoritative database (J-CHECK, 2016) and secondary source (OECD SIDS, 1995) for read across substance 2,4 -Dichloro-1 -methylbenzene (CAS no. 95 -73 -8) , biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of read across substance 2,4-Dichloro-1-methylbenzene. The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)). 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 0% by BOD and GC parameter in 28 days. Thus, based on percentage degradation, 2,4-Dichloro-1-methylbenzene is considered to be not readily biodegradable in nature.

 

Another supporting weight of evidence study was conducted for 28 days for evaluating the percentage biodegradability of read across substance (4 -Chloro-2 -methylphenoxy)acetic acid (CAS no. 94 -74 -6) (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 1, 0 and 2% by BOD, O2 consumption, TOC removal, test mat. analysis and HPLC parameter in 28 days. Thus, based on percentage degradation, (4 -Chloro-2 -methylphenoxy)acetic acid is considered to be not readily biodegradable in nature.

 

In an additional study of read across substance substance1-Chloronaphthalene (CAS no. 90 -13 -1) from authoritative database (J-CHECK, 2016), biodegradation experiment was carried out for 14 days for evaluating the percentage biodegradability of the substance. 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 0 and 1% by BOD and GC parameter in 14 days. Thus, based on percentage degradation, 1 -Chloronaphthalene is considered to be not readily biodegradable in nature.

 

On the basis of above results for target chemical1 -Bromo-3 -methoxybenzene(from OECD QSAR toolbox version 3.3 and EPI Suite) and for its read across substance (from authoritative database J-CHECK), it can be concluded that the test substance1 -Bromo-3 -methoxybenzene can 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 1 -Bromo-3 -methoxybenze ne (CAS No. 2398 -37 -0). If released in to the environment, 35.2% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 1 -Bromo-3 -methoxybenzene 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 1 -Bromo-3 -methoxybenzene 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 0.324%), indicates that 1 -Bromo-3 -methoxybenzene is not persistent in sediment.

Biodegradation in soil

The half-life period of1-Bromo-3-methoxybenzene(CAS No. 2398 -37 -0) 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, 57.9% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of1-Bromo-3-methoxybenzenein soil is estimated to be 75 days (1800 hrs). Based on this half-life value of1-Bromo-3-methoxybenzene, 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 1-Bromo-3-methoxybenzene can be considered to be not readily biodegradable in nature.