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Environmental fate & pathways

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Description of key information

Hydrolysis

HYDROWIN v2.00 program of Estimation Programs Interface (EPI Suite, 2017) prediction model was used to predict the hydrolysis half-life of test compound

3-methylbutyl benzoate (CAS No. 94 -46 -2). The estimated half-life of 3-methylbutyl benzoate was estimated to be 6.855yrs and 250.370 days at pH 7 and 8 (at 25 deg C) respectively, indicating that it is not hydrolysable.

Biodegradation in water

Biodegradability of 3-methylbutyl benzoate (CAS no. 94 -46 -2) is predicted using QSAR toolbox version 3.3 with logKow as the primary descriptor (2017). Test substance undergoes 81.08% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 3 -methylbutyl benzoate was estimated to be 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  3-methylbutyl benzoate (CAS No. 94 -46 -2). If released in to the environment, 21.7% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 3-methylbutyl benzoate in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the 3-methylbutyl benzoate is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of 3-methylbutyl benzoate in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.511%), indicates that 3-methylbutyl benzoate is not persistent in sediment.

Biodegradation in soil

The half-life period of test chemical 3-methylbutyl benzoate (CAS No. 94 -46 -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, 74.6% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 3-methylbutyl benzoate in soil is estimated to be 30 days (720 hrs). Based on this half-life value of 3-methylbutyl benzoate, 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.

Bioaccumulation: aquatic / sediment

From BCFBAF (v3.00) model of EPI suite Program, the estimated bio concentration factor (BCF) for 3-methylbutyl benzoate is 254.2 L/kg whole body w.w which does not exceed the bio concentration threshold of 2000. Thus it is concluded that 3-methylbutyl benzoate is not expected to bioaccumulate in the food chain.

Adsorption / desorption

The adsorption coefficient Koc in soil and in sewage sludge Isopentyl Benzoate i.e 3-methylbutyl benzoate(CAS No.94-46-2) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The reference substances were chosen according to functional group similarity with the test substance and calibration graph prepared. The reference substances were benzoic acid methylester, benzoic acid phenylester, xylene, ethylbenzene, toluene and naphthalene having Koc value ranging from 1.8 to 2.87. The Log Koc value was found to be 2.8762 ± 0.0001at 25°C.

Additional information

Hydrolysis

HYDROWIN v2.00 program of Estimation Programs Interface (EPI Suite, 2017) prediction model was used to predict the hydrolysis half-life of test compound

3-methylbutyl benzoate (CAS No. 94 -46 -2). The estimated half-life of 3-methylbutyl benzoate was estimated to be 6.855yrs and 250.370 days at pH 7 and 8 (at 25 deg C) respectively, indicating that it is not hydrolysable.

Biodegradation in water

Various predicted data for the target compound 3-methylbutyl benzoate (CAS No. 94-46-2) and various 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 3.3 with logKow as the primary descriptor, percentage biodegradability of test chemical 3-methylbutyl benzoate(CAS No. 94-46-2) was estimated. Test substance undergoes 81.08% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 3 -methylbutyl benzoate was estimated to be readily biodegradable in water.

 

In another prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound3-methylbutyl benzoate(CAS No. 94-46-2) 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 3-methylbutyl benzoate is expected to be readily biodegradable.

 

In a supporting weight of evidence study from peer reviewed journal (John J. Porter and Eric H. Snider, 1976), biodegradation study was conducted for 30 days for evaluating the percentage biodegradability of read across substance Butyl benzoate (CAS no. 136 -60 -7). Glucose-glutamic acid mixture was used as a reference substance for the biodegradation study. The results are compared with the chemical oxygen demand (COD) of the test chemical, which measures its maximum oxygen combining power; the results are also compared with the BOD test performed on a standard glucose-glutamic acid reference solution used for BOD caliberation. Reference substance i.e; glucose-glutamic acid mixture consumes 75 percent of its maximum oxygen requirement (COD) within 5 days and almost 100 percent in 30 days. Thus, based on this result, the reference substance is considered to be readily biodegradable. The percentage degradation of read across substance was determined to be 50 and 73% degradation by using BOD parameter after 5 and 30 days, respectively. The COD value of read across chemical was determined to be 2200000 mg/l, respectively. Thus, based on percentage degradation, Butyl benzoate is considered to be readily biodegradable in nature.

 

For the same read across chemical Butyl benzoate (CAS no. 136 -60 -7),biodegradation study was conducted for evaluating the percentage biodegradability of read across substance Butyl benzoate using an aerobic dilution method (HSDB, 2016). Test inoculum i.e an adapted culture was obtained from a treatment plant. Initial test substance conc. used in the study was 50 mg/l. The percentage degradation of read across substance was determined to be 100% in 24 hrs. Thus, based on percentage degradation, Butyl benzoate is considered to be readily biodegradable in nature.

 

Another weight of evidence study of biodegradation was conducted for 29 days for evaluating the percentage biodegradability of read across substance Methyl benzoate (CAS no. 93 -58 -3) (HSDB, 2016). The study was performed according to OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test). Activated sludge was used as a test inoculum. Initial test substance conc. used in the study was 28 mg/l. The percentage degradation of read across substance was determined to be 62% degradation by CO2 evolution in 29 days. Thus, based on percentage degradation, Methyl benzoate is considered to be readily biodegradable in nature.

 

On the basis of above results for target chemical 3 -methylbutyl benzoate (from OECD QSAR toolbox version 3.3 and EPI Suite, 2017) and for its read across substance (from peer reviewed journal and authoritative database HSDB, 2016), it can be concluded that the test substance 3 -methylbutyl benzoate can be expected to be 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  3-methylbutyl benzoate (CAS No. 94 -46 -2). If released in to the environment, 21.7% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 3-methylbutyl benzoate in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the 3-methylbutyl benzoate is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of 3-methylbutyl benzoate in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.511%), indicates that 3-methylbutyl benzoate is not persistent in sediment.

Biodegradation in soil

The half-life period of test chemical 3-methylbutyl benzoate (CAS No. 94 -46 -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, 74.6% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 3-methylbutyl benzoate in soil is estimated to be 30 days (720 hrs). Based on this half-life value of 3-methylbutyl benzoate, 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 3 -methylbutyl benzoate can be considered to be readily biodegradable in nature.

Bioaccumulation: aquatic / sediment

Five results including different predicted data from validated models and experimental data from authorative database for bioaccumulation (BCF) endpoint of target chemical 3-methylbutyl benzoate (Cas no. 94-46-2) were summarized as follows:

 

First prediction done using BCFBAF (v3.00) model indicate the estimated bio concentration factor (BCF) for 3-methylbutyl benzoate is 254.2 L/kg wet-wt which does not exceed the bioconcentration threshold of 2000. Thus it is concluded that 3-methylbutyl benzoate is not expected to bio accumulate in the aquatic environment.

 

Other predicted database PBT profiler indicate the Bioaccumulation factor (BCF) for test substance 3-methylbutyl benzoate was estimated to be 250 L/kg wet-wt at 25 deg.C.

 

Data from Scifinder database suggest the Bioconcentration factor (BCF) for target chemical 3-methylbutyl benzoate was predicted to be 653 at pH range 1-10 and temperature 25 deg.C

 

Whereas Chemspider - ACD/PhysChem Suite estimates the Bioconcentration factor (BCF) for target chemical 3-methylbutyl benzoate as 739.05 at pH 5.5 and 7.4 at temperature 25 deg.C.

All above predicted results of target supported by experimental data of read across chemical Butyl benzoate (Cas no. 94-46-2) which suggest an estimated BCF value of 62 was calculated in fish for butyl benzoate, using recommended regression-derived equation and water solubility of 59 mg/L. This BCF value suggests that bioconcentration in aquatic organisms is not important.

Thus based on the above information for bioaccumulation endpoint, it can be concluded that the test substance 3-methylbutyl benzoate (Cas no. 94-46-2) is expected to be non Bioaccumulative in aquatic environment.

Adsorption / desorption

Four studies including experimental study and predicted data from validated models for adsorption (KOC) endpoint of target chemical 3-methylbutyl benzoate (Cas no. 94-46-2) were summarized as follows:

 

First study from experimental report by UERL laboratory; 2017 which suggest the adsorption coefficient Koc in soil and in sewage sludge Isopentyl Benzoate i.e 3-methylbutyl benzoate(CAS No.94-46-2) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The reference substances were chosen according to functional group similarity with the test substance and calibration graph prepared. The reference substances were benzoic acid methylester, benzoic acid phenylester, xylene, ethylbenzene, toluene and naphthalene having Koc value ranging from 1.8 to 2.87. The Log Koc value was found to be 2.8762 ± 0.0001at 25°C.

 

Above results also supported by prediction using KOCWIN model (v2.00) of EPI suite which indicated the adsorption value of 3-methylbutyl benzoate was estimated as Koc 623.3 L/kg (log Koc = 2.79) by means of MCI method at 25 deg.C. This Koc value indicates that the substance 3-methylbutyl benzoate has moderate sorption to soil and sediment and therefore have slow migration potential to groundwater.

 

Another prediction model i.e Chemspider - ACD/PhysChem Suite for target indicate the soil adsorption coefficient i.e Koc value of test substance 3-methylbutyl benzoate was estimated to be 3935.49 (log koc:3.5) at pH 5.5 and 7.4 and temp.25 deg.C Koc values at mentioned pH indicates that the substance 3-methylbutyl benzoate has Strong sorption to soil and sediment and therefore have negligible migration potential to groundwater.

 

Last study from Scifinder database suggest the soil adsorption coefficient i.e Koc value of test substance 3-methylbutyl benzoate was estimated to be 3600 (Log koc:3.5) at pH range 1-10 at temperature 25 deg.C This Koc value at all range of pH condition indicates that the substance 3-methylbutyl benzoate has Strong sorption to soil and sediment and therefore have negligible migration potential to groundwater.

Thus all available studies for adsorption endpoint gives the common conclusion that the test substance 3-methylbutyl benzoate (Cas no. 94-46-2) is expected to have slow to negligible mobility in soil and sediment compartment.